leetcode Two Sum 哈希表

Given an array of integers, find two numbers such that they add up to a specific target number.

The function twoSum should return indices of the two numbers such that they add up to the target, where index1 must be less than index2. Please note that your returned answers (both index1 and index2) are not zero-based.

You may assume that each input would have exactly one solution.

Input: numbers={2, 7, 11, 15}, target=9
Output: index1=1, index2=2

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 Array Hash Table

刚开始直接两层for循环超时，哈哈，还是要用哈希表。

class Solution {public:vector<int> twoSum(vector<int>& nums, int target) {vector<int>res;if (!nums.size()) return res;map<int, int>Hash;for (int i = 0; i < nums.size(); i++){if (Hash.find(target - nums[i]) != Hash.end()){res.push_back(Hash[target - nums[i]]+1);res.push_back(i+1);return res;}Hash[nums[i]] = i;}return res;}};