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
    
      twoSum(vector
     
      & nums, int target) {        int n = nums.size();        for (int i = 0; i < n; ++ i) {            for (int j = i + 1; j < n; ++ j) {                if (target == nums[i] + nums[j]) {                    return {i, j};                }            }        }        return nums;    }};