Solved Problems

Output a string to the console

Write the string "Hello World!" to STDOUT
java
System.out.println("Hello World!");
System.out.printf("Hello World!\n");
csharp
System.Console.WriteLine("Hello World!")
fantom
echo("Hello World!")

Define a string containing special characters

Define the literal string "\#{'}${"}/"
java
String special = "\\#{'}${\"}/";
csharp
string verbatim = @"\#{'}${""""}/";
string cStyle = "\\#{'}${\"\"}/";
fantom
special := Str<|\#{'}${"}/|>

Define a multiline string

Define the string:
"This
Is
A
Multiline
String"
java
String text = "This\nIs\nA\nMultiline\nString";
String text =
"This\n" +
"Is\n" +
"A\n" +
"Multiline\n" +
"String"
csharp
string output = "This\nIs\nA\nMultiline\nString";
string output = @"This
Is
A
Multiline
String";
fantom
s := "This
Is
A
Multiline
String"

Define a string containing variables and expressions

Given variables a=3 and b=4 output "3+4=7"
java
System.out.println(a + "+" + b + "=" + (a+b));
System.out.printf("%d+%d=%d\n", a, b, a + b);
csharp
int a = 3;
int b = 4;
Console.WriteLine("{0}+{1}={2}", a,b,a+b);
fantom
echo("$a+$b=${a+b}")

Reverse the characters in a string

Given the string "reverse me", produce the string "em esrever"
java
String reverse = new StringBuffer("reverse me").reverse().toString();
String reverse = new StringBuilder("reverse me").reverse().toString();
String reverse = StringUtils.reverse("reverse me");
csharp
var str = "reverse me";
Console.WriteLine(new String(str.Reverse().ToArray()));
fantom
"reverse me".reverse

Reverse the words in a string

Given the string "This is a end, my only friend!", produce the string "friend! only my end, the is This"
java
List list = new ArrayList();
StringTokenizer st = new StringTokenizer(text, " ");
while(st.hasMoreTokens()) {
list.add(0, st.nextToken());
}
StringBuffer sb = new StringBuffer();
for (Iterator iterator = list.iterator(); iterator.hasNext();) {
String word = (String) iterator.next();
sb.append(word);
if (iterator.hasNext()) {
sb.append(" ");
}
}
String reversed = sb.toString();
List<String> ls = Arrays.asList("This is the end, my only friend!".split("\\s"));
Collections.reverse(ls);
StringBuilder sb = new StringBuilder(32); for (String s : ls) sb.append(" ").append(s);
String reversed = sb.toString().trim();
String reversed = StringUtils.reverseDelimited("This is the end, my only friend!", ' ');
csharp
var str = "This is a end, my only friend!";
str = String.Join(" ", str.Split().Reverse().ToArray());
Console.WriteLine(str);
fantom
"This is a end, my only friend!".split.reverse.join(" ")

Text wrapping

Wrap the string "The quick brown fox jumps over the lazy dog. " repeated ten times to a max width of 78 chars, starting each line with "> ", yielding this result:

> The quick brown fox jumps over the lazy dog. The quick brown fox jumps
> over the lazy dog. The quick brown fox jumps over the lazy dog. The
> quick brown fox jumps over the lazy dog. The quick brown fox jumps
> over the lazy dog. The quick brown fox jumps over the lazy dog. The
> quick brown fox jumps over the lazy dog. The quick brown fox jumps
> over the lazy dog. The quick brown fox jumps over the lazy dog. The
> quick brown fox jumps over the lazy dog.
java
String prefix = "> "; String input = "The quick brown fox jumps over the lazy dog.";

String[] lines = WordUtils.wrap(StringUtils.repeat(input, 10), 72 - prefix.length()).split("\n");

for (String line : lines) System.out.printf("%s%s\n", prefix, line);
csharp
using System;
using System.Text;
using System.Linq; // used for Array.ToList() extension

public class TextWrapper {

/// <summary>
/// Wrap the given text to a given width.
/// </summary>
/// <param name="text">The text to be wrapped</param>
/// <param name="width">The maximum width of each line</param>
/// <param name="prefix">Begin each line with this prefix</param>
/// <returns>The wrapped text</returns>
public string Wrap(string text, int width, string prefix) {

var words = text.Split(' ').ToList();
var result = new StringBuilder(prefix);

width = width - prefix.Length;
prefix = "\n" + prefix;

int lineSize = 0;
foreach (var word in words) {
int wordLen = word.Length;

// Do we need to start a new line?
if ((lineSize + wordLen) > width) {
result.Remove(result.Length - 1, 1); // remove trailing space
lineSize = 0;
result.Append( prefix );
}

result.Append(word).Append(' ');
lineSize += wordLen + 1;
}

return result.ToString();
}

public static void Main() {
var prefix = "> ";
var sentence = "The quick brown fox jumps over the lazy dog. ";

var text = "";
for (int i = 0; i < 10; i++)
text += sentence;

// The description said lines of length 78, but
// the example was 72...
Console.WriteLine(new TextWrapper().Wrap(text, 72, prefix));
}
}
fantom
buf := Buf()
10.times { buf.writeChars("The quick brown fox jumps over the lazy dog. ") }
buf.flip

out := Env.cur.out
sep := ">"; max := 72 - sep.size - 1
acc := 0; Str? s := null
while ((s = buf.readStrToken) != null)
{
if (acc == 0)
out.print(sep)

acc += s.size
if (acc > max)
{
out.print("\n$sep")
acc = s.size
}
out.print(" $s")
buf.readStrToken(4096) { !it.isSpace }
acc++
}

Remove leading and trailing whitespace from a string

Given the string "  hello    " return the string "hello".
java
String s = " hello "; String trimmed = s.trim();
csharp
string str = " hello ";
str = str.Trim();
Console.WriteLine(str);
fantom
s := " hello ".trim

Make a string uppercase

Transform "Space Monkey" into "SPACE MONKEY"
java
String upper = text.toUpperCase();
csharp
string output = "Space Monkey"

System.Console.WriteLine(output.ToUpper())
fantom
s := "Space Monkey".localeUpper

Make a string lowercase

Transform "Caps ARE overRated" into "caps are overrated"
java
"Caps ARE overRated".toLowerCase();
csharp
string str = "Caps ARE overRated";
str = str.ToLower() ;
Console.WriteLine(str);
fantom
s := "Caps ARE overRated".localeLower

Capitalise the first letter of each word

Transform "man OF stEEL" into "Man Of Steel"
java
String input = "man OF stEEL";
StringTokenizer tokenizer = new StringTokenizer(input);
StringBuffer sb = new StringBuffer();
while (tokenizer.hasMoreTokens()) {
String word = tokenizer.nextToken();
sb.append(word.substring(0, 1).toUpperCase());
sb.append(word.substring(1).toLowerCase());
sb.append(' ');
}
String text = sb.toString();
StringBuilder sb = new StringBuilder("man OF stEEL"); String s = sb.toString();
int last = s.length() - 1;

for (int i = 0; i <= last; ++i)
if (Character.isSpaceChar(s.charAt(i)) && i < last) { ++i; sb.setCharAt(i, Character.toUpperCase(s.charAt(i))); }
else if (i == 0) sb.setCharAt(i, Character.toUpperCase(s.charAt(i)));
else sb.setCharAt(i, Character.toLowerCase(s.charAt(i)));
Matcher m = Pattern.compile("(\\w+)").matcher("man OF stEEL"); StringBuffer sb = new StringBuffer(32), rsb = new StringBuffer(8);

while (m.find())
{
rsb.replace(0, rsb.length(), m.group().toLowerCase()); rsb.setCharAt(0, Character.toUpperCase(rsb.charAt(0)));
m.appendReplacement(sb, rsb.toString());
}
m.appendTail(sb);
String text = WordUtils.capitalizeFully("man OF stEEL");
csharp
System.Threading.Thread.CurrentThread.CurrentCulture.TextInfo.ToTitleCase("man OF stEEL".ToLowerInvariant());
fantom
"man OF stEEL".split.map { it.localeLower.localeCapitalize }.join(" ")

Find the distance between two points

java
double distance = Point2D.distance(x1, y1, x2, y2);
Point2D point1 = new Point2D.Double(x1, y1);
Point2D point2 = new Point2D.Double(x2, y2);
double distance = point1.distance(point2);
double distance = Math.hypot(x2-x1, y2-y1);
csharp
System.Drawing.Point p = new System.Drawing.Point(13, 14),
p1 = new System.Drawing.Point(10, 10);
double distance = Math.Sqrt(Math.Pow(p1.X - p.X, 2) + Math.Pow(p1.Y - p.Y, 2)));
fantom
px1 := 34.0f; py1 := 78.0f; px2 := 67.0f; py2 := -45.0f
distance := |Float x1, Float y1, Float x2, Float y2 -> Float|
{ ((x2-x1).pow(2.0f) + (y2-y1).pow(2.0f)).sqrt }

distance(px1, py1, px2, py2)

Zero pad a number

Given the number 42, pad it to 8 characters like 00000042
java
String formatted = new DecimalFormat("00000000").format(42);
String formatted = String.format("%08d", 42);
csharp
string.Format("{0,8:D8}", 42);
fantom
formatted := 42.toStr.padl(8, '0')
formatted := 42.toLocale("00000000")

Right Space pad a number

Given the number 1024 right pad it to 6 characters "1024  "
java
private static String spaces(int spaces) {
StringBuffer sb = new StringBuffer();
for(int i=0; i<spaces; i++) {
sb.append(' ');
}
return sb.toString();
}

private static String rightPad(int number, int spaces) {
String numberString = String.valueOf(number);
return numberString + spaces(spaces - numberString.length());
}
String text = StringUtils.rightPad(String.valueOf(1024), 6)
String formatted = String.format("%-6d", 1024);
csharp
public class NumberRightPadding {
public static void Main() {
string withStringDotFormat = string.Format("{0,-6}", 1024);
string withToStringDotPadRight = 1024.ToString().PadRight(6);
}
}
fantom
formatted := 1024.toStr.padr(6)

Format a decimal number

Format the number 7/8 as a decimal with 2 places: 0.88
java
String formatted = String.format("%3.2f", 7./8.);
csharp
public class FormatDecimal {
public static void Main() {
decimal result = decimal.Round( 7 / 8m, 2);
System.Console.WriteLine(result);
}
}
fantom
formatted := (7.0/8.0).toLocale("0.00")

Left Space pad a number

Given the number 73 left pad it to 10 characters "        73"
java
private static String spaces(int spaces) {
StringBuffer sb = new StringBuffer();
for(int i=0; i<spaces; i++) {
sb.append(' ');
}
return sb.toString();
}

private static String leftPad(int number, int spaces) {
String numberString = String.valueOf(number);
return spaces(spaces - numberString.length()) + numberString;
}
String formatted = String.format("%10d", 73);
csharp
public class NumberLeftPadding {
public static void Main() {
string withStringDotFormat = string.Format("{0,10}", 73);
string withToStringDotPadLeft = 73.ToString().PadLeft(10);
}
}
fantom
formatted := 73.toStr.padl(10)

Generate a random integer in a given range

Produce a random integer between 100 and 200 inclusive
java
Random random = new Random();
int randomInt = random.nextInt(200-100+1)+100;
csharp
System.Random r = new System.Random();
int random = r.Next(100,201);
fantom
r := Int.random(100..200)

Generate a repeatable random number sequence

Initialise a random number generator with a seed and generate five decimal values. Reset the seed and produce the same values.
java
int[] arr1 = genFillRand(new int[5], new Random(12345), 100, 200);
int[] arr2 = genFillRand(new int[5], new Random(12345), 100, 200);

for (int[] arr : new int[][]{ arr1, arr2 }) { for (int i : arr) System.out.printf("%d ", i); System.out.println(); }
csharp
using System;

public class RepeatableRandom {
public static void Main() {
var r = new Random(12); // seed is 12

for (int i = 0; i < 5; i++)
Console.WriteLine(r.Next());

r = new Random(12);

for (int i = 0; i < 5; i++)
Console.WriteLine(r.Next());
}
}

fantom
rand := Random.makeSeeded(12345)
first := Int[,].fill(0,5).map { rand.next(100..200) }

rand2 := Random.makeSeeded(12345)
second := Int[,].fill(0,5).map { rand2.next(100..200) }

Check if a string matches a regular expression

Display "ok" if "Hello" matches /[A-Z][a-z]+/
java
if ("Hello".matches("[A-Z][a-z]+")) {
System.out.println("ok");
}
csharp
if (Regex.IsMatch("Hello", "[A-Z][a-z]+"))
{
Console.WriteLine("ok");
}
fantom
if (Regex<|[A-Z][a-z]+|>.matches("Hello"))
echo("ok")

Check if a string matches with groups

Display "two" if "one two three" matches /one (.*) three/
java
Pattern pattern = Pattern.compile("one (.*) three");
Matcher matcher = pattern.matcher("one two three");
if (matcher.matches()) {
System.out.println(matcher.group(1));
}
csharp
using System;
using System.Text.RegularExpressions;

public class RegexBackReference {
public static void Main() {
var oneTwoThree = "one two three";
var pattern = "one (.*) three";

Match match = Regex.Match(oneTwoThree, pattern);

// group 0 is the entire match. 1 is the first backreference
Console.WriteLine(match.Groups[1]);
}
}
fantom
m := Regex<|one (.*) three|>.matcher("one two three")
if (m.matches)
echo("${m.group(1)}")

Check if a string contains a match to a regular expression

Display "ok" if "abc 123 @#$" matches /\d+/
java
Pattern pattern = Pattern.compile("\\d+");
Matcher matcher = pattern.matcher(text);
if (matcher.find()) {
System.out.println("ok");
}
csharp
if(System.Text.RegularExpressions.Regex.IsMatch("abc 123 @#$",@"\d+")){
Console.WriteLine("ok");
}
fantom
m := Regex<|\d+|>.matcher("abc 123 @#\$")
if (m.find)
echo("ok")

Loop through a string matching a regex and performing an action for each match

Create a list [fish1,cow3,boat4] when matching "(fish):1 sausage (cow):3 tree (boat):4" with regex /\((\w+)\):(\d+)/
java
List list = new ArrayList();
Pattern pattern = Pattern.compile("\\((\\w+)\\):(\\d+)");
Matcher matcher = pattern.matcher(text);
while(matcher.find()) {
list.add(matcher.group(1)+matcher.group(2));
}
csharp
using System;
using System.Collections.Generic;
using System.Text.RegularExpressions;

public static class extensions {
public static IList<string> Map(this string me, string pattern, Func<Match, string> action){
IList<string> matches = new List<string>();
foreach (Match match in Regex.Matches(me,pattern)){
matches.Add(action(match));
}
return matches;
}
}

class Test
{
static void Main()
{
IList<string> list = "(fish):1 sausage (cow):3 tree (boat):4".Map(@"\((\w+)\):(\d+)", (m) => {return m.Groups[1].Value + m.Groups[2].Value;});
}
}
fantom
m := Regex<|\((\w+)\):(\d+)|>.matcher(s)
list := Str[,]
while (m.find) { list.add("${m.group(1)}${m.group(2)}") }

Replace all regex matches in a string with a static string

Transform "She sells sea shells" into "She X X shells" by replacing /se\w+/ with "X"
java
String replaced = text.replaceAll("se\\w+", "X");
csharp
using System.Text.RegularExpressions;

class SolutionXX
{
static void Main()
{
string text = "She sells sea shells";
string result = Regex.Replace(text, @"se\w+", "X");
}
}
fantom
replaced := Regex<|se\w+|>.split("She sells sea shells").join("X")

Define an empty list

Assign the variable "list" to a list with no elements
java
List list = Collections.emptyList();
String[] list = {};
csharp
var list = new List<object>();
fantom
list := [,]

Define a static list

Define the list [One, Two, Three, Four, Five]
java
List<String> numbers = new ArrayList<String>();
Collections.addAll(numbers, "One", "Two", "Three", "Four", "Five");
List numbers = new ArrayList();
numbers.add("One");
numbers.add("Two");
numbers.add("Three");
numbers.add("Four");
numbers.add("Five");
List numbers = Arrays.asList(new String[]{"One", "Two", "Three", "Four", "Five"});
String[] numbers = {"One", "Two", "Three", "Four", "Five"};
List numbers = new ArrayList(){{put("One"); put("Two"); put("Three"); put("Four"); put("Five"); }};
csharp
IList<string> list = new string[]{"One","Two","Three","Four","Five"};
fantom
list := ["One", "Two", "Three", "Four", "Five"]

Join the elements of a list, separated by commas

Given the list [Apple, Banana, Carrot] produce "Apple, Banana, Carrot"
java
StringBuffer sb = new StringBuffer();
for (Iterator it = fruit.iterator(); it.hasNext();) {
sb.append(it.next());
if (it.hasNext()) {
sb.append(", ");
}
}
String result = sb.toString();
StringBuilder sb = new StringBuilder(fruit.get(0));
for (String item : fruit.subList(1, fruit.size())) sb.append(", ").append(item);
String result = sb.toString();
String result = StringUtils.join(fruit, ", ");
csharp
using System.Collections.Generic;
public class JoinEach {
public static void Main() {
var list = new List<string>() {"Apple", "Banana", "Carrot"};
System.Console.WriteLine( string.Join(", ", list.ToArray()) );
}
}
fantom
["Apple", "Banana", "Carrot"].join(", ")

Join the elements of a list, in correct english

Create a function join that takes a List and produces a string containing an english language concatenation of the list. It should work with the following examples:
join([Apple, Banana, Carrot]) = "Apple, Banana, and Carrot"
join([One, Two]) = "One and Two"
join([Lonely]) = "Lonely"
join([]) = ""
java
private String join(List elements) {
if (elements == null || elements.size() == 0) {
return "";
} else if (elements.size() == 1) {
return elements.get(0).toString();
} else if (elements.size() == 2) {
return elements.get(0) + " and " + elements.get(1);
}
StringBuffer sb = new StringBuffer();
for (Iterator it = elements.iterator(); it.hasNext();) {
String next = (String) it.next();
if (sb.length() > 0) {
if (it.hasNext()) {
sb.append(", ");
} else {
sb.append(", and ");
}
}
sb.append(next);
}
return sb.toString();
}
System.out.println(join(fruit));
csharp
using System.Collections.Generic;
using System.Linq;

public class CSharpListToEnglishList {
public string JoinAsEnglishList (List<string> words) {
switch (words.Count) {
case 0: return "";
case 1: return words[0];
case 2: return string.Format("{0} and {1}", words.ToArray());
default:
return JoinAsEnglishList( new List<string>() {
string.Join(", ", words.Take(words.Count - 1).ToArray()) + ",",
words.Last()
});
}
}
// Driver...
public static void Main() {
var joiner = new CSharpListToEnglishList();
System.Console.WriteLine(
joiner.JoinAsEnglishList(new List<string>() { "Apple", "Banana", "Carrot", "Orange" }) );
System.Console.WriteLine(
joiner.JoinAsEnglishList(new List<string>() { "Apple", "Banana", "Carrot" }) );
System.Console.WriteLine(
joiner.JoinAsEnglishList(new List<string>() { "One", "Two" }) );
System.Console.WriteLine(
joiner.JoinAsEnglishList(new List<string>() { "Lonely" }) );
System.Console.WriteLine(
joiner.JoinAsEnglishList(new List<string>()) );
}
}
fantom
join := |List list -> Str|
{
switch(list.size)
{
case 0: return ""
case 1: return list[0]
case 2: return list.join(" and ")
default: return list[0..-2].join(", ") + ", and " + list[-1]
}
}

echo(join(["Apple", "Banana", "Carrot"]))
echo(join(["One", "Two"]))
echo(join(["Lonely"]))
echo(join([,]))

Produce the combinations from two lists

Given two lists, produce the list of tuples formed by taking the combinations from the individual lists. E.g. given the letters ["a", "b", "c"] and the numbers [4, 5], produce the list: [["a", 4], ["b", 4], ["c", 4], ["a", 5], ["b", 5], ["c", 5]]
java
List<String> combinations = new ArrayList<String>();

for (int number : numbers)
for (String letter : letters)
combinations.add(letter + ":" + Integer.toString(number));
SortedSet<AbstractMap.SimpleImmutableEntry<String, Integer> > combinations =
new TreeSet<AbstractMap.SimpleImmutableEntry<String, Integer> >(new CombinationComparator());

for (int number : numbers)
for (String letter : letters)
combinations.add(new AbstractMap.SimpleImmutableEntry<String, Integer>(letter, Integer.valueOf(number)));
csharp
using System.Collections.Generic;
public class ListCombiner {
public static void Main() {
var letters = new List<char>() { 'a', 'b', 'c' };
var numbers = new List<int>() { 1, 2, 3 };

// result is a list that contaings lists of objects
var result = new List<List<object>>();
foreach (var l in letters) {
foreach (var n in numbers) {
result.Add(new List<object>() { l, n });
}
}
}
}
fantom
[4,5].each |Int i| { ["a","b","c"].each |Str s| { r.add([i,s]) } }

From a List Produce a List of Duplicate Entries

Taking a list:
["andrew", "bob", "chris", "bob"]

Write the code to produce a list of duplicates in the list:
["bob"]
java
List listOfDuplicates = new ArrayList(Arrays.asList(new String[]{"andrew", "bob", "chris", "bob"}));

Set set = new HashSet(listOfDuplicates);
for (Object element : set)
listOfDuplicates.remove(element);
csharp
List<String> values = new List<string> {"andrew", "bob", "chris", "bob"};

var duplicates = values
.GroupBy(i => i)
.Where(j => j.Count() > 1)
.Select(s => s.Key);
foreach (var duplicate in duplicates)
{
Console.WriteLine(duplicate);
}
fantom
nameCounts := Str:Int[:] { def = 0 }
["andrew", "bob", "chris", "bob"].each |Str v| { nameCounts[v]++ }
results := nameCounts.findAll |Int v, Str k->Bool| { v > 1 }.keys
echo(results.join(","))

Fetch an element of a list by index

Given the list [One, Two, Three, Four, Five], fetch the third element ('Three')
java
String result = list.get(2);
csharp
string[] items = new string[] { "One", "Two", "Three", "Four", "Five" };
List<string> list = new List<string>(items);
string third = list[2]; // "Three"
// Make sure you import the System.Linq namespace.
// This is not the preferred way of indexing if you are using Lists.
string[] items = new string[] { "One", "Two", "Three", "Four", "Five" };
IEnumerable<string> list = new List<string>(items);
string third = list.ElementAt(2); // Three
fantom
["One", "Two", "Three", "Four", "Five"][2]
["One", "Two", "Three", "Four", "Five"].get(2)

Fetch the last element of a list

Given the list [Red, Green, Blue], access the last element ('Blue')
java
String result = list.get(list.size() - 1);
csharp
string[] items = new string[] { "Red", "Green", "Blue" };
List<string> list = new List<string>(items);
string last = list[list.Count - 1]; // "Blue"
// Make sure you import the System.Linq namespace.
// This is not the preferred way of finding the last element if you are using Lists.
string[] items = new string[] { "Red", "Green", "Blue" };
IEnumerable<string> list = new List<string>(items);
string last = list.Last(); // "Blue"
fantom
["Red", "Green", "Blue"][-1]
["One", "Two", "Three", "Four", "Five"].last

Find the common items in two lists

Given two lists, find the common items. E.g. given beans = ['broad', 'mung', 'black', 'red', 'white'] and colors = ['black', 'red', 'blue', 'green'], what are the bean varieties that are also color names?
java
List beans = Arrays.asList(new String[]{"broad", "mung", "black", "red", "white"});
List colors = Arrays.asList(new String[]{"black", "red", "blue", "green"});

List common = ListUtils.intersection(beans, colors);
csharp
// Make sure you import the System.Linq namespace.
// This example uses arrays as the underlying implementation, but any IEnumerable type can be used - including List.
IEnumerable<string> beans = new string[] { "beans", "mung", "black", "red", "white" };
IEnumerable<string> colors = new string[] { "black", "red", "blue", "green" };
var intersect = beans.Intersect(colors); // ['red', 'black']
fantom
beans := ["broad", "mung", "black", "red", "white"]
colors := ["black", "red", "blue", "green"]
echo(beans.intersection(colors))

Display the unique items in a list

Display the unique items in a list, e.g. given ages = [18, 16, 17, 18, 16, 19, 14, 17, 19, 18], display the unique elements, i.e. with duplicates removed.
java
Set<Integer> ages = new TreeSet<Integer>(Arrays.asList(new Integer[]{18, 16, 17, 18, 16, 19, 14, 17, 19, 18}));

System.out.println(ages);
csharp
using System.Collections.Generic;
using System.Linq;
public class UniqueElements {
public static void Main() {
var list = new List<int>() { 18, 16, 17, 18, 16, 19, 14, 17, 19, 18 };
var uniques = list.Distinct();
}
}
fantom
uniqueAges := [18, 16, 17, 18, 16, 19, 14, 17, 19, 18].unique
echo(uniqueAges)

Remove an element from a list by index

Given the list [Apple, Banana, Carrot], remove the first element to produce the list [Banana, Carrot]
java
list.remove(0);
csharp
class Solution1516
{
static void Main()
{
List<string> fruit = new List<string>() { "Apple", "Banana", "Carrot" };
fruit.RemoveAt(0);
}
}
fantom
list := ["Apple", "Banana", "Carrot"]
list.removeAt(0)

Remove the last element of a list

java
list.remove(list.size() - 1);
csharp
List<string> fruits = new List() { "apple", "banana", "cherry" };
fruits.RemoveAt(fruits.Length - 1);
fantom
list := ["Apple", "Banana", "Carrot"]
list.removeAt(-1)
list := ["Apple", "Banana", "Carrot"]¨
list.pop

Rotate a list

Given a list ["apple", "orange", "grapes", "bananas"], rotate it by removing the first item and placing it on the end to yield ["orange", "grapes", "bananas", "apple"]
java
list.add(list.remove(0));
Collections.rotate(list, -1);
csharp
var lst = new LinkedList<String>(new String[] {"apple", "orange", "grapes", "banana"});
lst.AddLast(lst.First());
lst.DeleteFirst();
fantom
list := ["apple", "orange", "grapes", "bananas"]
list.add(list.removeAt(0))

Gather together corresponding elements from multiple lists

Given several lists, gather together the first element from every list, the second element from every list, and so on for all corresponding index values in the lists. E.g. for these three lists, first = ['Bruce', 'Tommy Lee', 'Bruce'], last = ['Willis', 'Jones', 'Lee'], years = [1955, 1946, 1940] the result should produce 3 actors. The middle actor should be Tommy Lee Jones.
java
String[] first = new String[]{"Bruce", "Tommy Lee", "Bruce"};
String[] last = new String[]{"Willis", "Jones", "Lee"};
String[] years = new String[]{"1955", "1946", "1940"};

List<String[]> list = new ArrayList<String[]>(); list.add(first); list.add(last); list.add(years);

String[] result = zip(",", list);
csharp
String[] first = { "Bruce", "Tommy Lee", "Bruce" };
String[] last = { "Willis", "Jones", "Lee" };
int[] years = { 1955, 1946, 1940 };
var actors = first.Zip(last, (f, l) => Tuple.Create(f, l)).Zip(years, (t, y) => Tuple.Create(t.Item1, t.Item2, y)).ToArray();
Debug.Assert(actors[1].Equals(Tuple.Create("Tommy Lee", "Jones", 1946)));
fantom
r := [,]
first.size.times |Int i| { r.add([first[i], last[i], years[i]]) }

echo(r)

List Combinations

Given two source lists (or sets), generate a list (or set) of all the pairs derived by combining elements from the individual lists (sets). E.g. given suites = ['H', 'D', 'C', 'S'] and faces = ['2', '3', '4', '5', '6', '7', '8', '9', '10', 'J', 'Q', 'K', 'A'], generate the deck of 52 cards, confirm the deck size and check it contains an expected card, say 'Ace of Hearts'.
java
SortedSet<AbstractMap.SimpleImmutableEntry<String, String> > cards =
new TreeSet<AbstractMap.SimpleImmutableEntry<String, String> >(new CardComparator());

for (String suite : suites)
for (String face : faces)
cards.add(new AbstractMap.SimpleImmutableEntry<String, String>(suite, face));

Boolean containsEntry = cards.contains(new AbstractMap.SimpleImmutableEntry<String, String>("h", "A"));

if (containsEntry) System.out.println("Deck contains 'Ace of Hearts'");
else System.out.println("'Ace of Hearts' not in deck");
csharp
using System;
using System.Collections.Generic;
using System.Linq;

namespace Combinations
{
class Program
{
public static void Main(string[] args)
{
// Define the given lists
// Since List`1 implements the interface IEnumerable`1, this can easily be redefined as List`1.
IEnumerable<string> suites = new string[] { "H", "D", "C", "S" };
IEnumerable<string> faces = new string[] { "2", "3", "4", "5", "6", "7", "8", "9", "10", "J", "Q", "K", "A" };

// LINQ Query to perform a Cartesian product and create an anonymous type to hold the results.
// "var" is required to define this as an IEnumerable`1
var deck =
from suite in suites // For each suite in suites
from face in faces // Match it with a face in face.
select new
{
Suite = suite,
Face = face
};

// Verify the count (uses LINQ extension)
if (deck.Count() == 52)
{
Console.WriteLine("Count matches!");
}

// Verify that the Ace of Hearts is in the deck (uses LINQ extension)
if (deck.Contains(new {Suite = "H", Face = "A"}))
{
Console.WriteLine("Ace of Hearts found!");
}

// Example of how to iterate through the list.
// "var" here is required since we are using an anonymous type
foreach(var card in deck)
{
Console.WriteLine("Suite: {0} Face: {1}", card.Suite, card.Face);
}

// If you desire to work with a List`1, you can convert this to a normal list at any time:
Console.WriteLine("\nConverting to list!");
var list = deck.ToList();
Console.WriteLine("Suite: {0} Face: {1}", list[5].Suite, list[5].Face);
Console.WriteLine("List count: {0}", list.Count); // 52

Console.ReadLine();
}
}
}
fantom
r := [,]
["2","3","4","5","6","7","8","9","10","J","Q","K","A"].each |Str c|
{ ["H","D","C","S"].each |Str s| { r.add([c,s]) } }

q := ["A","H"]
result := r.contains(q)
echo("Deck size=${r.size}, contains $q? -> $result")

Perform an operation on every item of a list

Perform an operation on every item of a list, e.g.
for the list ["ox", "cat", "deer", "whale"] calculate
the list of sizes of the strings, e.g. [2, 3, 4, 5]
java
public class SolutionXX {
public static void main(String[] args) {
String[] list = {"ox", "cat", "deer", "whale"};
for (String str : list) {
System.out.println(str.length() + " ");
}
}
}
csharp
using System.Collections.Generic;
public class OperationOnEach {
public static void Main() {
var list = new List<string>() { "ox", "cat", "deer", "whale" };
list.ForEach( System.Console.WriteLine );
}
}
fantom
["ox", "cat", "deer", "whale"].map { it.size }

Split a list of things into numbers and non-numbers

Given a list that might contain e.g. a string, an integer, a float and a date,
split the list into numbers and non-numbers.
java
public class NumbersSolution {
public static void main(String[] args) {
List<Object> items = Arrays.asList(new Object[] { new Date(), 12L, 15.4, 99, "x" } ) ;
List<Object> numbers = new ArrayList<Object>() ;
List<Object> nonNumbers = new ArrayList<Object>() ;
for (Object item : items )
(item instanceof Number ? numbers : nonNumbers).add(item) ;
}
}
public class NumbersSolution {
public static void main() {
List<Object> numbers = new ArrayList<Object>() ;
List<Object> nonNumbers = new ArrayList<Object>() ;
for (Object item : new Object[] { new Date(), 12L, 15.4, 99, "x" } )
(item instanceof Number ? numbers : nonNumbers).add(item) ;
}
}
csharp
using System;
using System.Collections.Generic;
using System.Linq;

// AFAIK, there just isn't a good way to do this in C#
public class ListSplitter {
public static bool IsNumeric(object o) {
var d = new Decimal();
return decimal.TryParse(o.ToString(), out d);
}
public static void Main() {
var list = new List<object>() { "foo", DateTime.Now, 1, "bar", 2.4 };

// the Where method does the work...
var numbers = list.Where( el => IsNumeric(el) );
var nonNumbers = list.Where( el => ! IsNumeric(el) );
}

}
fantom
things := ["hello", 25, 3.14, Time.now]
numbers := things.findType(Num#)
nonNumbers := things.exclude { numbers.contains(it) }

Create a histogram map from a list

Given the list [a,b,a,c,b,b], produce a map {a:2, b:3, c:1} which contains the count of each unique item in the list
java
Map map = new HashMap();
for (Iterator it = list.iterator(); it.hasNext();) {
String s = (String) it.next();
if (!map.containsKey(s)) {
map.put(s, new Integer(1));
} else {
map.put(s, new Integer(((Integer)map.get(s)).intValue() + 1));
}
}
LinkedMap histogram = new LinkedMap();

for (Object letter : list)
histogram.put(letter, !histogram.containsKey(letter) ? 1 : MapUtils.getIntValue(histogram, letter) + 1);
csharp
using System.Collections.Generic;
using System.Linq;

// This is a "functional" C# approach

// NOTE: In C# "maps" are of type Dictionary<Tkey, TValue>
// so our histogram map is of type Dictionary<object, int>
public class HistogramMap {
public Dictionary<object, int> FromList(List<object> list) {
// The "Aggregate" method works like "inject" in many other languages.
return list.Aggregate(
new Dictionary<object, int>(),
(map, obj) => {
// If this is the first time we've seen this obj, set the count to 0
if (!map.ContainsKey(obj)) map[obj] = 0;

// Increment the count
map[obj]++;

// Return the map for the next iteration.
// NOTE: This does NOT return from our "FromList" method
return map;
}
);
}

public static void Main() {
// Create our Histogram Map from a new list
var map = new HistogramMap().FromList(
new List<object>() { 'a', 'b', 'a', 'c', 'b', 'b' }
);

// This just prints the result
System.Console.WriteLine (
string.Join (", ",
// "Select" works like "map" or "collect" in many other languages
map.Select( kvp =>
string.Format("{0} : {1}", kvp.Key, kvp.Value)
).ToArray()
)
);
}
}
new[] {"a","b","a","c","b","b"}
.GroupBy(s => s)
.Select(s => new { Value = s.Key, Count = s.Count() })
.ToList()
.ForEach(e => Console.WriteLine("{0} : {1} ", e.Value, e.Count));
fantom
list := ["a","b","a","c","b","b"]
map := [Str:Int][:]
list.each |Str s, Int i| { if(!map.containsKey(s)) map.add(s,1); else map[s] = ++map[s] }
echo (map)

Categorise a list

Given the list [one, two, three, four, five] produce a map {3:[one, two], 4:[four, five], 5:[three]} which sorts elements into map entries based on their length
java
SortedMap<Integer, List<String> > map = new TreeMap<Integer, List<String> >(); int key; List<String> vlist;

for (String item : list)
{
key = item.length(); vlist = map.containsKey(key) ? map.get(key) : new ArrayList<String>();
vlist.add(item); map.put(key, vlist);
}
MultiValueMap map = new MultiValueMap();
for (Object item : list) map.put(((String) item).length(), item);
csharp
using System.Collections.Generic;
using System.Linq;
public class ListCategorizer {
public static void Main() {
var list = new List<string>() { "one", "two", "three", "four", "five" };
var categories = list.GroupBy(el => el.Length)
.ToDictionary( g => g.Key, // key
g => g.ToList() ); // value
}
}
fantom
list := ["one", "two", "three", "four", "five"]
map := [Int:List][:]
list.each { List l := map[it.size] ?: [,]; map[it.size] = l.add(it) }
echo(map)

Perform an action if a condition is true (IF .. THEN)

Given a variable name, if the value is "Bob", display the string "Hello, Bob!". Perform no action if the name is not equal.
java
if (name.equals("Bob")) {
System.out.println("Hello, Bob!");
}
csharp
if (name == "Bob") Console.WriteLine("Hello, {0}!", name);
fantom
if (name=="Bob") echo("Hello, Bob!")

Perform different actions depending on a boolean condition (IF .. THEN .. ELSE)

Given a variable age, if the value is greater than 42 display "You are old", otherwise display "You are young"
java
if (age > 42) {
System.out.println("You are old");
} else {
System.out.println("You are young");
}
System.out.println("You are " + ((age>42)?"old":"young"));
csharp
int age = 41;

if (age > 42)

System.Console.WriteLine("You are old");
else
System.Console.WriteLine("You are young");


fantom
if (age > 42)
echo("You are old")
else
echo("You are young")
echo((age > 42) ? "You are old" : "You are young")

Perform different actions depending on several boolean conditions (IF .. THEN .. ELSIF .. ELSE)

java
if (age > 84) System.out.println("You are really ancient");
else if (age > 30) System.out.println("You are middle-aged");
else System.out.println("You are young");
csharp
if (age > 84) Console.WriteLine("You are really ancient");
else if (age > 30) Console.WriteLine("You are middle-aged");
else Console.WriteLine("You are young");
Console.WriteLine("You are {0}", ((age > 84) ? "really ancient" : (age > 30) ? "middle-aged" : "young"));
fantom
if (age > 84)
echo("You are really ancient")
else if (age > 30)
echo("You are middle-aged")
else
echo("You are young")

Replacing a conditional with many branches with a switch/case statement

Many languages support more compact forms of branching than just if ... then ... else such as switch or case or match. Use such a form to add an appropriate placing suffix to the numbers 1..40, e.g. 1st, 2nd, 3rd, 4th, ..., 11th, 12th, ... 39th, 40th
java
String[] array = new String[40];
for(int n = 1; n <= array.length; n++)
array[n-1] = Integer.toString(n);
for(int n = 0; n < array.length; n++)
{
int y = Integer.parseInt(array[n]);
if(array[n].length() > 1)
y = Integer.parseInt(array[n].substring(1));
switch(y)
{
case 1: {array[n] += "st"; break;}
case 2: {array[n] += "nd"; break;}
case 3: {array[n] += "rd"; break;}
default: array[n] += "th";
}
}
csharp
public static string GetOrdinal(int i)
{
if (i > 10 && i < 20) return i.ToString() + "th";
switch (i % 10)
{
case 1:
return i.ToString() + "st";
case 2:
return i.ToString() + "nd";
case 3:
return i.ToString() + "rd";
default:
return i.ToString() + "th";
}
}
public static string GetOrdinal(int i)
{
if (i > 10 && i < 20) return i.ToString() + "th";
switch (i % 10)
{
case 1:
return i.ToString() + "st";
break;
case 2:
return i.ToString() + "nd";
break;
case 3:
return i.ToString() + "rd";
break;
default:
return i.ToString() + "th";
break;
}
}
fantom
suffix := |Int n -> Str|
{
if ((4..20).contains(n % 100))
return "th"

switch((n.toStr)[-1])
{
case '1': return "st"
case '2': return "nd"
case '3': return "rd"
default: return "th"
}
}

(1..40).each { echo("$it${suffix(it)}") }

Perform an action multiple times based on a boolean condition, checked before the first action (WHILE .. DO)

Starting with a variable x=1, Print the sequence "1,2,4,8,16,32,64,128," by doubling x and checking that x is less than 150.
java
int x = 1;
while (x < 150) {
System.out.println(x+",");
x*=2;
}
csharp
int x = 1;

while (x < 150)
{
x *= 2;
Console.Write("{0},", x);
}
fantom
x := 1
while (x < 150) {
Env.cur.out.print("$x,")
x *= 2
}
echo

Perform an action multiple times based on a boolean condition, checked after the first action (DO .. WHILE)

Simulate rolling a die until you get a six. Produce random numbers, printing them until a six is rolled. An example output might be "4,2,1,2,6"
java
int rnd;
do {
rnd = (int)(Math.random()*6)+1;
System.out.print(rnd);
if (rnd!=6) {
System.out.print(",");
}
} while(rnd!=6);
csharp
System.Random die = new System.Random();
int roll;

do
{
roll = die.Next(1, 6);
Console.Write(roll);
if (roll < 6) Console.Write(",");
}
while (roll != 6);
fantom
rnd := 0
while(rnd != 6) {
rnd = Int.random(1..6)
Env.cur.out.print(rnd)
if (rnd != 6)
Env.cur.out.print(",")
}
echo

Perform an action a fixed number of times (FOR)

Display the string "Hello" five times like "HelloHelloHelloHelloHello"
java
for(int i=0;i<5;i++) {
System.out.print("Hello");
}
csharp
string text = "Hello";

for (int i = 0; i < 5; i++)
{
Console.Write(text);
}
fantom
5.times { Env.cur.out.print("Hello") }
for (i := 0; i < 5; i++)
Env.cur.out.print("Hello")
(1..5).each { Env.cur.out.print("Hello") }

Perform an action a fixed number of times with a counter

Display the string "10 .. 9 .. 8 .. 7 .. 6 .. 5 .. 4 .. 3 .. 2 .. 1 .. Liftoff!"
java
for(int i=10; i>=1; i--) {
System.out.print(i + " .. ");
}
System.out.print("Liftoff!");
csharp
for (int i = 10; i > 0; i--)
{
Console.Write("{0} .. ", i);
}

Console.WriteLine("Liftoff!");
fantom
(10..1).each { Env.cur.out.print("$it .. ") }
Env.cur.out.print("Liftoff!")
for (i := 10; i >= 1; i--)
Env.cur.out.print("$i .. ")
Env.cur.out.print("Liftoff!")

Read the contents of a file into a string

java
String text = FileUtils.readFileToString(new File("Solution109.java"), "UTF-8");
RandomAccessFile raf = null; byte[] buffer; String text = null;

try
{
raf = new RandomAccessFile("Solution399.java", "r");
buffer = new byte[(int)raf.length()]; raf.read(buffer);
text = new String(buffer);
}
csharp
string contents = System.IO.File.ReadAllText("filename.txt");
fantom
contents := File(`file.text`).readAllStr

Process a file one line at a time

Open the source file to your solution and print each line in the file, prefixed by the line number, like:
1> First line of file
2> Second line of file
3> Third line of file
java
BufferedReader br = null;
try {
br = new BufferedReader(new FileReader("Solution104.java"));
String line = null;
int lineNumber = 1;
while ((line=br.readLine())!=null) {
System.out.println(lineNumber + "> " + line);
lineNumber++;
}
} catch (IOException e) {
throw new RuntimeException(e);
} finally {
if (br!=null) {
try {
br.close();
} catch (Exception e) {
// ok
}
}
}
LineNumberReader lnr = null; PrintWriter pw = null; String line;

try
{
lnr = new LineNumberReader(new FileReader("Solution400.java"));
pw = new PrintWriter(System.out);
while ((line = lnr.readLine()) != null) pw.printf("%d> %s\n", lnr.getLineNumber(), line);
}
csharp
int counter = 0;

// If the file is large, you would want to buffer this instead of reading everything at once
foreach (string line in System.IO.File.ReadAllLines("filename.txt"))
{
Console.WriteLine("{0}> {1}", ++counter, line);
}
fantom
File(`input.text`).readAllLines.each |Str s, Int i| { echo("${i+1}> $s") }

Write a string to a file

java
FileWriter fw = null;

try
{
fw = new FileWriter("test.txt");
fw.write("This line overwites file contents!");
}
PrintWriter pw = null;

try
{
pw = new PrintWriter(new BufferedWriter(new FileWriter("test.txt")));
pw.print("This line overwites file contents!");
}
csharp
System.IO.File.WriteAllText("filename.txt", "Some text to write to the file");
fantom
File(`out.txt`).out.writeChars("some text").flush

Append to a file

java
FileWriter fw = null;

try
{
fw = new FileWriter("test.txt", true);
fw.write("This line appended to file!");
}
PrintWriter pw = null;

try
{
pw = new PrintWriter(new BufferedWriter(new FileWriter("test.txt", true)));
pw.print("This line appended to file!");
}
csharp
System.IO.File.AppendAllText("filename.txt", "Some text to append to the file");
fantom
File(`out.txt`).out(true).writeChars("some text").flush

Process each file in a directory

java
for (File file : (new File("c:\\")).listFiles()) process(file);
csharp
foreach (string filename in System.IO.Directory.GetFiles(directory)) ProcessFile(filename);
fantom
File(`./`).list.each { process(it) }

Parse a date and time from a string

Given the string "2008-05-06 13:29", parse it as a date representing 6th March, 2008 1:29:00pm in the local time zone.
java
DateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm");
Date date = df.parse("2008-05-06 13:29");
DateTimeFormatter fmt = DateTimeFormat.forPattern("yyyy-MM-dd HH:mm");
DateTime dt = fmt.parseDateTime("2008-05-06 13:29");
csharp
DateTime parsedDate = DateTime.Parse("2008-05-06 13:29");
// Ideally, you would catch the potential FormatException or use DateTime.TryParse in production code.
fantom
dt := DateTime.fromLocale("2008-05-06 13:29", "YYYY-MM-DD hh:mm")

Display information about a date

Display the day of month, day of year, month name and day name of the day 8 days from now.
java
Calendar cal = Calendar.getInstance();
cal.add(DAY_OF_YEAR, 8);
System.out.println(cal.get(DAY_OF_MONTH));
System.out.println(cal.get(DAY_OF_YEAR));
System.out.println(new SimpleDateFormat("MMMM").format(cal.getTime()));
System.out.println(new SimpleDateFormat("EEEE").format(cal.getTime()));
csharp
DateTime date = DateTime.Today.AddDays(8);

Console.WriteLine("Day of month: " + date.Day);
Console.WriteLine("Day of year: " + date.DayOfYear);
Console.WriteLine("Month name: " + date.ToString("MMMM"));
Console.WriteLine("Day name: " + date.ToString("dddd"));

// The two ToString calls will use the current locale.
// To get localised month and day names, see http://msdn.microsoft.com/en-us/library/8tfzyc64.aspx
fantom
date := Date.today + 8day
echo(date.day)
echo(date.dayOfYear)
echo(date.month.localeFull)
echo(date.weekday.localeFull)

Display a date in different locales

Display a language/locale friendly version of New Year's Day for 2009 for several languages/locales. E.g. for languages English, French, German, Italian, Dutch the output might be something like:

Thursday, January 1, 2009
jeudi 1 janvier 2009
giovedì 1 gennaio 2009
Donnerstag, 1. Januar 2009
donderdag 1 januari 2009

(Indicate in comments where possible if any language specific or operating system configuration needs to be in place.)
java
Calendar cal = Calendar.getInstance();
cal.set(2009, Calendar.JANUARY, 1);
Locale[] locales = { ENGLISH, FRENCH, ITALIAN, GERMAN, new Locale("nl") };

for (Locale l : locales) {
System.out.println(getDateInstance(FULL, l).format(cal.getTime()));
}
csharp
using System.Globalization;

DateTime newYearsDay = new DateTime(2009, 1, 1);
CultureInfo[] locales = {
CultureInfo.CreateSpecificCulture("en-US"),
CultureInfo.CreateSpecificCulture("fr-FR"),
CultureInfo.CreateSpecificCulture("de-DE"),
CultureInfo.CreateSpecificCulture("it-IT"),
CultureInfo.CreateSpecificCulture("nl-NL")
};

foreach (CultureInfo locale in locales)
{
Console.WriteLine(newYearsDay.ToString("D", locale));
}
fantom
// May require modification of Fantom distribution t
// for undefined locales - basically just create a '<locale-name>.props' plain text file with values like this:
// sunAbbr=Sun
// ..
// sunFull=Sunday
["en", "fr", "ru"].map { Locale(it) }.each |Locale l| {
l.use { echo(Date(2009, Month.jan, 1).toLocale("WWWW, MMMM D, YYYY")) }
}

Display the current date and time

Create a Date object representing the current date and time. Print it out.
If you can also do this without creating a Date object you can show that too.
java
import java.util.Date;

public class SolutionXX {
public static void main(String[] args) {
Date now = new Date();
System.out.println(now.toString());
}
}
csharp
// Creating a variable first:
DateTime now = DateTime.Now;
Console.WriteLine(now);

// Without creating a variable:
Console.WriteLine(DateTime.Now);
fantom
echo(DateTime.now)
OOP

Define a class

Declare a class named Greeter that takes a string on creation and greets using this string if you call the "greet" method.
java
class Greeter
{
public Greeter(String whom) { this.whom = whom; }
public void greet() { System.out.printf("Hello, %s\n", whom); }
private String whom;
}

public class Solution381 {
public static void main(String[] args) {
(new Greeter("world")).greet();
}
}
csharp
using System;

class Greeter
{
private string name {get;set;}

public void Greet(){
Console.WriteLine("Hello, {0}",name);
}

public Greeter(string name){
this.name = name;
}
}

class Test
{
static void Main()
{
new Greeter("Dante").Greet();
}
}
fantom
class Greeter
{
private Str whom
new make(Str whom) { this.whom = whom }
Void greet() { echo("Hello, $whom") }
}

Greeter("world").greet

Instantiate object with mutable state

Reimplement the Greeter class so that the 'whom' property or data member remains private but is mutable, and is provided with getter and setter methods. Invoke the setter to change the greetee, invoke 'greet', then use the getter in displaying the line, "I have just greeted {whom}.".

For example, if the greetee is changed to 'Tommy' using the setter, the 'greet' method would display:

Hello, Tommy!

The getter would then be used to display the line:

I have just greeted Tommy.
java
class Greeter {
private String whom;

public Greeter(String whom) {
this.whom = whom;
}

public String getWhom() {
return whom;
}

public void setWhom(String whom) {
this.whom = whom;
}

public void greet() {
System.out.println("Hello " + whom + "!");
}
}
Greeter greeter = new Greeter("World");
greeter.greet();
greeter.setWhom("Tommy");
greeter.greet();
System.out.println("I have just greeted " + greeter.getWhom() + ".");
csharp
class Greeter
{
public string Name {get;set;}

public void Greet(){
Console.WriteLine("Hello, {0}",Name);
}

public Greeter(string name){
this.Name = name;
}

// Driver
public static void Main()
{
var g = new Greeter("Dante");

g.Name = "Tommy";
g.Greet();
Console.Write("I have just greated {0}", g.Name);
}
}
fantom
class Greeter
{
new make(Str whom) { this.whom = whom }
Void greet() { echo("Hello, $whom!") }
Str whom
}

greeter := Greeter("world")
greeter.greet
greeter.whom = "Tommy"
echo("I have just greeted ${greeter.whom}.")

Implement Inheritance Heirarchy

Implement a Shape abstract class which will form the base of an inheritance hierarchy that models 2D geometric shapes. It will have:

* A non-mutable 'name' property or data member set by derived or descendant classes at construction time
* A 'area' method intended to be overridden by derived or descendant classes ( double precision floating point return value)
* A 'print' method (also for overriding) will display the shape's name, area, and all shape-specific values

Two derived or descendant classes will be created:
* Circle    -> Constructor requires a '
radius' argument, and a 'circumference' method to be implemented  
* Rectangle -> Constructor requires '
length' and 'breadth' arguments, and a 'perimeter' method to be implemented 

Instantiate an object of each class, and invoke each objects '
print' method to show relevant details.
java
/*
* Will work with version 1.4 if you remove the @Override annotation
* and declare floating point numbers using the primitive "double"
*/
abstract class Shape {
protected final String name;
public Shape(String name) {
this.name = name;
}
public abstract Double area();
public abstract void print();
}
class Circle extends Shape {
private Double radius;
public Circle(Double radius) {
super("circle");
this.radius = radius;
}
@Override
public Double area() {
return Math.PI * Math.pow(radius, 2);
}
@Override
public void print() {
System.out.println("A " + name + " with radius " + radius
+ ", area " + area() + " and circumference "
+ circumference() + ".");
}
public Double circumference() {
return 2 * Math.PI * radius;
}
}
class Rectangle extends Shape {
private Double length, breadth;
public Rectangle(Double length, Double breadth) {
super("Rectangle");
this.length = length;
this.breadth = breadth;
}
@Override
public Double area() {
return length * breadth;
}
public Double perimeter() {
return 2 * length + 2 * breadth;
}
@Override
public void print() {
System.out.println("A " + name + " with length " + length
+ ", breadth " + breadth + ", area " + area()
+ " and perimeter " + perimeter() + ".");
}
}
Circle circle = new Circle(4d);
circle.print();
Rectangle rectangle = new Rectangle(2d, 5.5);
rectangle.print();
csharp
// While abstract classes do exist in C#, it is most common to use
// an interface in this type of situation.
// It is a common idiom to prefix interface names with an I
public interface IShape {
string Name { get; }
double Area { get; }
void Print();
}

public class Circle : IShape {

private double Radius { get; set; }
public Circle(double radius) {
Name = "Circle";
Radius = radius;
}

public string Name { get; private set; }
public double Area {
get {
return Math.PI * Radius * Radius;
}
}
public double Circumference {
get {
return Math.PI * (Radius + Radius);
}
}

public void Print() {
Console.WriteLine( " Name: {0}\n Area: {1}\n Circumference: {2}\n Radius: {3}",
this.Name,
this.Area,
this.Circumference,
this.Radius
);
}
}

public class Rectangle : IShape {

private double Length { get; set; }
private double Breadth { get; set; }
public Rectangle(double length, double breadth) {
Name = "Rectangle";
Length = length;
Breadth = breadth;
}

public string Name { get; private set; }
public double Area {
get {
return Length * Breadth;
}
}
public double Perimeter {
get {
return (Length * 2) + (Breadth * 2 );
}
}

public void Print() {
Console.WriteLine( " Name: {0}\n Area: {1}\n Perimeter: {2}\n Length: {3}\n Breadth: {4}",
this.Name,
this.Area,
this.Perimeter,
this.Length,
this.Breadth
);
}
}

// Driver
public class InheritanceHeirarchy {
public static void _Main() {
var c = new Circle(2.1);
c.Print();

Console.WriteLine();

var r = new Rectangle(2.2, 3.3);
r.Print();
}
}
fantom
abstract class Shape
{
const Str name
new make(Str name) { this.name = name }
abstract Float area()
abstract Void print()
}

class Circle : Shape
{
private Float radius

new make(Float radius) : super("circle") { this.radius = radius }
Float circumference() { return 2 * Float.pi * radius }
override Float area() { return Float.pi * radius.pow(2.0f) }
override Void print()
{
echo("I am a $name with radius $radius, area $area
and circumference $circumference")
}
}

class Rectangle : Shape
{
private Float length
private Float breadth

new make(Float length, Float breadth) : super("rectangle")
{
this.length = length
this.breadth = breadth
}
Float perimeter() { return 2 * (length + breadth) }
override Float area() { return length * breadth }
override Void print()
{
echo("I am a $name with length $length, breadth $breadth,
area $area and perimeter $perimeter")
}
}


circle := Circle(4.0f)
circle.print
rectangle := Rectangle(2.0f, 5.5f)
rectangle.print
XML

Process an XML document

Given the XML Document:

<shopping>
  <item name="bread" quantity="3" price="2.50"/>
  <item name="milk" quantity="2" price="3.50"/>
</shopping>

Print out the total cost of the items, e.g. $14.50
java
// solution uses JAXP and SAX included in Java API since version >= 1.5
class ShoppingContentHandler extends DefaultHandler {
Double priceSum = 0d;
@Override
public void startElement(String uri, String localName, String name,
Attributes attributes) throws SAXException {
if(name.equals("item")) {
String quantityString = attributes.getValue(attributes.getIndex("quantity"));
String priceString = attributes.getValue(attributes.getIndex("price"));
Integer quantity = Integer.parseInt(quantityString);
Double price = Double.parseDouble(priceString);
priceSum += (quantity * price);
}
}
public Double getPriceSum() {
return priceSum;
}
}

SAXParserFactory parserFactory = SAXParserFactory.newInstance();
try {
SAXParser parser = parserFactory.newSAXParser();
XMLReader reader = parser.getXMLReader();
ShoppingContentHandler contentHandler = new ShoppingContentHandler();
reader.setContentHandler(contentHandler);
reader.parse(new InputSource(new FileReader("shopping.xml")));
System.out.printf("$%.2f", contentHandler.getPriceSum());

} catch (ParserConfigurationException e) {
e.printStackTrace();
} catch (SAXException e) {
e.printStackTrace();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
csharp
System.Xml.XmlDocument doc = new System.Xml.XmlDocument();
doc.LoadXml(
@"<shopping>
<item name='bread' quantity='3' price='2.50'/>
<item name='milk' quantity='2' price='3.50'/>
</shopping>");

string decimalSeparator= System.Globalization.CultureInfo.CurrentCulture.NumberFormat.CurrencyDecimalSeparator;

double sum=0;

foreach(System.Xml.XmlNode nodo in doc.SelectNodes("/shopping/item")){
sum += int.Parse(nodo.Attributes["quantity"].InnerText) * double.Parse(nodo.Attributes["price"].InnerText.Replace(".",decimalSeparator));
}
Console.WriteLine("{0:#.00}",sum);
fantom
sum := 0.0
root := XParser(File(`shop.xml`).in).parseDoc.root
if (root.name == "shopping")
{
root.elems.each
{
if (it.name == "item")
{
quantity := Int.fromStr(it.get("quantity"))
price := Decimal.fromStr(it.get("price"))
sum += quantity * price;
}
}
}
echo("\$$sum")

create some XML programmatically

Given the following CSV:

bread,3,2.50
milk,2,3.50

Produce the equivalent information in XML, e.g.:

<shopping>
  <item name="bread" quantity="3" price="2.50" />
  <item name="milk" quantity="2" price="3.50" />
</shopping>
java
// In this solution JAXB is used to created the xml output.
// JAXB is included in Java 1.6. Runs with 1.5 if you include JAXB Jars
// in the classpath.
class Item {
// Of course you use getters and setters and declare attributes private.
// In this sample a "dirty" way is chosen to keep LOC low.
@XmlAttribute
String name;
@XmlAttribute
Integer quantity;
@XmlAttribute
Double price;
}

@XmlRootElement
class Shopping {
@XmlElement
Set<Item> items = new HashSet<Item>();
}

String line = null;
Shopping shopping = new Shopping();
try {
BufferedReader reader = new BufferedReader(new FileReader("shopping.csv"));
while ((line = reader.readLine()) != null) {
String[] parts = line.split(",");
Item item = new Item();
item.name = parts[0];
item.quantity = Integer.parseInt(parts[1]);
item.price = Double.parseDouble(parts[2]);
shopping.items.add(item);

}
JAXB.marshal(shopping, "D:" + File.separatorChar + "shopping.auto.xml");
} catch (IOException e) {
e.printStackTrace();
}
csharp
string cvs ="bread,3,2.50\nmilk,2,3.50";
IList<string> rows = cvs.Split('\n');

System.Text.StringBuilder sb = new System.Text.StringBuilder("<shopping>");
foreach(string row in rows){
IList<string> data = row.Split(',');
sb.AppendFormat("<item name='{0}' quantity='{1}' price='{2}' />",data[0],data[1],data[2]);
}
sb.Append("</shopping>");
fantom
sum := 0.0
rows := CsvInStream(File(`shop.csv`).in).readAllRows

doc := XDoc()
doc.root = XElem("shopping")
{
root := it
rows.each |Str[] row|
{
root.add(XElem("item")
{
XAttr("name", row[0]),
XAttr("quantity", row[1]),
XAttr("price", row[2])
})
}
}

os := File(`shop.xml`).out
doc.write(os)
os.close

Greatest Common Divisor

Find the largest positive integer that divides two given numbers without a remainder. For example, the GCD of 8 and 12 is 4.

java
static int gcd(int a, int b) {
if (Math.min(a, b) == 0)
return Math.max(a, b);
else
return gcd(Math.min(a, b), Math.abs(a - b));
}
csharp
public static int gcd(int a, int b)
{
if (b == 0)
return a;
else
return gcd(b, a % b);
}
fantom
gcd := |Int a, Int b -> Int| {
pair := [a, b].sort
while (pair.first != 0)
pair.set(1, pair.last % pair.first).swap(0, 1)
return pair.last
}
echo(gcd(12, 8)) // a>b, result == 4
echo(gcd(1029, 1071)) // a<b, result == 21