Solution to r/DailyProgrammer challenge #313 (https://www.reddit.com/r/dailyprogrammer/comments/68oda5/20170501_challenge_313_easy_subset_sum/)

subset-sum.js

export default arr => arr.some(x => arr.includes(-x));

subset-sum.test.js

import subsetSum from './subset-sum.js';

test('[1, 2, 3] -> false', () => {
	expect(subsetSum([1, 2, 3])).toBeFalsy();
});

test('[-5, -3, -1, 2, 4, 6] -> false', () => {
	expect(subsetSum([-5, -3, -1, 2, 4, 6])).toBeFalsy();
});

test('[] -> false', () => {
	expect(subsetSum([])).toBeFalsy();
});

test('[-1, 1] -> true', () => {
	expect(subsetSum([-1, 1])).toBeTruthy();
});

test('[-97364, -71561, -69336, 19675, 71561, 97863] -> true', () => {
	expect(subsetSum([-97364, -71561, -69336, 19675, 71561, 97863])).toBeTruthy();
});

test('[-53974, -39140, -36561, -23935, -15680, 0] -> true', () => {
	expect(subsetSum([-53974, -39140, -36561, -23935, -15680, 0])).toBeTruthy();
});