Two_sum.cpp

/*Problem Statement: Given an array of integers nums[] and an integer target, return indices of the two numbers such that their sum is equal to the target.

Note: Assume that there is exactly one solution, and you are not allowed to use the same element twice.
Example: If target is equal to 6 and num[1] = 3, then nums[1] + nums[1] = target is not a solution. */
vector<int> twoSum(vector<int>& nums, int target) {

    vector<int> res;
    unordered_map<int, int> mp;

    for (int i = 0; i < nums.size(); ++i) {

   	 if (mp.find(target - nums[i]) != mp.end()) {

   		 res.emplace_back(i);
   		 res.emplace_back(mp[target - nums[i]]);
   		 return res;
   	 }

   	 mp[nums[i]] = i;
    }

    return res;
}