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Lists

Output

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));

java 1.6 or later

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)));

erlang

Combinations =
lists:foldl(fun (Number, Acc) -> Acc ++ lists:map(fun (Letter) -> {Letter, Number} end, Letters) end, [], Numbers),

erlang

Combinations = lists:keysort(2, sofs:to_external(sofs:product(sofs:set(Letters), sofs:set(Numbers))))

erlang

[[A, B] || A <- ["a", "b", "c"], B <- [4, 5]].

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