Two sum solution added

Author: piyushkhemka

Two Sum.cpp

@@ -0,0 +1,25 @@
+class Solution {
+public:
+    vector<int> twoSum(vector<int>& nums, int target) {
+        unordered_map<int,int> m;
+        vector<int> result;
+        int n = nums.size();
+        
+        for(int i = 0; i<n; i++)
+            m.insert(make_pair(nums[i], i));
+            
+        for(int i = 0; i<n; i++) {
+            int key = target-nums[i];
+            auto it = m.find(key);
+            if(it != m.end() && it->second != i) {
+                result.push_back(i);
+                result.push_back(it->second);
+                return result;
+            }
+        }
+        
+        return result;
+        
+    }
+};
+