1. Two Sum https://leetcode.com/problems/two-sum/description/
不使用额外空间需要n*n的复杂度
class Solution { public: vector<int> twoSum(vector<int>& nums, int target) { for(int i=0;i<nums.size()-1;i++){ for(int j=i+1;j<nums.size();j++){ if(nums[i] + nums[j] == target){ vector<int> result; result.push_back(i); result.push_back(j); return result; } } } return vector<int>(); } };