two sum: Given nums = [2,7,11,15], target = 9, Because nums[0] + nums[1] = 2 + 7 = 9, return [0, 1]

gistfile1.txt

#include <unordered_map>

class Solution {
public:
  vector<int>  twoSum(vector<int> &number, int targe)
  {
    //Key is the number and value is its index in the vector.
    unordered_map<int, int > hash;
    vector<int> result;
    
    for(i = 0; i < numbers.size(); i++) {
      int numberToFind = target - numbers[i];
      
      //if numberToFind is found in map, return them 
      if(hash.find(numberToFind) != hash.end()) {
        result.push_back(hash[numberToFind]);
        result.push_back(i);
        return result;
        }
        
        //number was not found .Put it in the map
        hash[number[i]] = i;
        } //end for loop
        
        return result;
        } //end func
};//end class