[Codewars] 011: Sum of Pairs

题目

（5kyu）Given a list of integers and a single sum value, return the first two values (parse from the left please) in order of appearance that add up to form the sum.

sum_pairs([11, 3, 7, 5],         10)
#              ^--^      3 + 7 = 10
== [3, 7]

sum_pairs([4, 3, 2, 3, 4],         6)
#          ^-----^         4 + 2 = 6, indices: 0, 2 *
#             ^-----^      3 + 3 = 6, indices: 1, 3
#                ^-----^   2 + 4 = 6, indices: 2, 4
#  * entire pair is earlier, and therefore is the correct answer
== [4, 2]

sum_pairs([0, 0, -2, 3], 2)
#  there are no pairs of values that can be added to produce 2.
== None/nil/undefined (Based on the language)

sum_pairs([10, 5, 2, 3, 7, 5],         10)
#              ^-----------^   5 + 5 = 10, indices: 1, 5
#                    ^--^      3 + 7 = 10, indices: 3, 4 *
#  * entire pair is earlier, and therefore is the correct answer
== [3, 7]

Negative numbers and duplicate numbers can and will appear.
这一题跟LeetCode的“两数之和”一样。

我的答案

def sum_pairs(ints, s):
    cache = set()
    for i in ints:
        other = s - i
        if other in cache:
            return [other, i]
        cache.add(i)