find 3 elements of an unsorted array whose sum is 0.

triples.d

import std.stdio;
import std.typecons;

alias Tuple!(int, int) Pair;

// O(n^2)
auto triple(int[] array) {
	Pair[int] map;
	for (int j = 1; j < array.length-1; ++j) {
		for (int i = 0; i < j; ++i) {
			map[array[i] + array[j]] = tuple(i,j);
		}

		for (int k = j + 1; k < array.length; ++k) {
			if (-array[k] in map) {
				auto p = map[-array[k]];
				return tuple(array[p[0]], array[p[1]], array[k]);
			}
		}
	}
	return tuple(-1,-1,-1);
}

void main() {
	auto array = [1,7,-2,6,-1,8,-9,3,4,-5];
	writeln(triple(array));
}