1、Two Sum

Two Sum

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：每两个相加，比较target。
代码：

class Solution {public:    vector<int> twoSum(vector<int>& nums, int target) {        vector<int> a;        for(int i = 0; i < nums.size(); i++)            for(int j = i+1; j < nums.size(); j++)                if(nums[i] + nums[j] == target){                    a.push_back(i);                    a.push_back(j);                }        return a;    }};

知识点：vector