The sum of the two numbers in the leetcode array and the specified value

The sum of the two numbers in the leetcode array and the specified value

Question:

Given an array of integers, find two numbers such that they add up to a specific target number.

The function twoSum shocould return indices of the two numbers such that they add up to the target, where index1 must be less than index2. Please note that your returned answers (both index1 and index2) are not zero-based.

You may assume that each input wowould have exactly one solution.

Input: numbers = {2, 7, 11, 15}, target = 9
Output: index1 = 1, index2 = 2

Ideas:

The most direct thinking is of course the two attempts, but the time complexity is O (n2), so the time complexity is not as much as you have to accept, so try again, if you can use target to subtract a number from the array and then get the result to search for it in the array, if you can find it, then you will undoubtedly need a data structure that can be searched. Think of map, traverse the resume search database first, and then follow the above ideas. The time complexity is O (n), and the price is space for time. Is this the optimal solution? Let's take a look at it later. My code passes through leetcode OJ.
Code:

class Solution {public:    vector
 
   twoSum(vector
  
    &numbers, int target) {        std::map
   
     finder;for (int i = 0; i
    
     (val, i));}for (int i = 0; i
     
       re;if(finder[left]==i){    continue;}else if (finder[left]