Leetcode-1 Two Sum

#1.　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.

Example:

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

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

 题解：暴力求解，时间复杂度O(n²)

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