Two Sum (LeetCode) | Linear Time Algorithm

TwoSum.cpp

class Solution {
public:
    vector<int> twoSum(vector<int>& nums, int target) {
        unordered_map<int, int> mp;
        
        for(int i = 0; i < nums.size(); ++i) {
            int complement = target - nums[i];
            
            if(mp.find(complement) != mp.end()) {
                return {mp[complement], i};
            }
            
            mp[nums[i]] = i;            
        }
        
        return {-1, -1};
    }
};