1. Two Sum（LeetCode）

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].

class Solution {
public:
    vector<int> twoSum(vector<int>& nums, int target) {
        vector<int> num=nums;
        sort(num.begin(), num.end());
        int len = num.size();
        int left = 0;
        int right = len - 1;
        while (left < right)
        {
            if ((num[left] + num[right])>target)
                right--;
            else
            if ((num[left] + num[right]) < target)
                left++;
            else
                break;
        }
        vector<int> vet;
        for(int i=0;i<len;i++)
        {
            if(nums[i]==num[left]||nums[i]==num[right])
               vet.push_back(i);
        }
       
        return vet;
    }
};