leetcode——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].

class Solution{    public:    vector<int> twoSum(vector<int> &numbers, int target)    {               vector<int> num = numbers;        std::sort(num.begin(), num.end());        int length = numbers.size();        int left = 0;        int right = length - 1;        int sum = 0;        vector<int> index;        while(left < right)        {            sum = num[left] + num[right];            if(sum == target)            {                // find the index from the old array                for(int i = 0; i < length; ++i)                {                    if(numbers[i] == num[left])                    {                        index.push_back(i);                    }                    else if(numbers[i] == num[right])                    {                        index.push_back(i);                    }                    if(index.size() == 2)                    {                        break;                    }                }                break;            }            else if(sum > target)            {                --right;            }            else            {                ++left;            }        }        return index;    }};