leetcode 1. two sum

06 Oct 2017 | 알고리즘 프로그래밍

문제출처

문제

Given an array of integers, return indices of the two numbers such that they add up to a specific target.

You may assume that each input would have exactly one solution, and you may not use the same element twice.

Example:
Given nums = [2, 7, 11, 15], target = 9,

Because nums[0] + nums[1] = 2 + 7 = 9,
return [0, 1].

풀이코드

def two_sum(nums, target):
    for idx, num in enumerate(nums):
        if target - num in nums:
            return idx, nums.index(target-num)

다른사람풀이

hash table을 활용 (O(n))

def two_sum(nums,target):
    dic = {}
    i = 0
    for num in nums:
        if target - num in dic:
            return dic[target-num], i
        d[num] = i
        i += 1