Leetcode #1 2sum

题目

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].

思路：取出一个数n，再从剩下的数中寻找target-n，使用一趟hash即可。

class Solution:    def twoSum(self, nums, target):        """        :type nums: List[int]        :type target: int        :rtype: List[int]        """        result = {}        for idx, i in enumerate(nums): # 一定要是当前的index，防止[3,3] 返回[0,0]的情况            tmp = target - i            if tmp in result:                return [result[tmp], idx]            result[i] = nums.index(i)        return 'no solution'

这里只考虑一组解的情况，输出所有结果的如下：

待续