Create 3-Sum.cpp

Author: mkraghav

cpp/3-Sum.cpp

@@ -0,0 +1,47 @@
+class Solution {
+public:
+    vector<vector<int>> threeSum(vector<int>& nums) {
+   
+        //
+        vector<vector<int>> res;
+        //sort
+        sort(nums.begin(),nums.end());
+        
+        for(unsigned int i = 0; i < nums.size();i++){
+             // initialize left and right 
+           //to handle duplicates
+            if(i > 0 && nums[i]==nums[i-1])
+                continue;
+             int l = i + 1; 
+            int r = nums.size() - 1; 
+            int x = nums[i]; 
+            
+            while (l < r) 
+            {    
+                if (x + nums[l] + nums[r] == 0) {
+                    res.push_back(vector<int>{x,nums[l],nums[r]});
+                    //to handle duplicates
+                    while (l<r && nums[l] == nums[l+1]) 
+                        l++;
+                    // to handle duplicates
+                    while (l<r && nums[r] == nums[r-1]) 
+                        r--;
+                    l++;
+                    r--;
+                    //break;
+                }
+                // If sum of three elements is less 
+                // than zero then increment in left 
+                else if (x + nums[l] + nums[r] < 0) 
+                    l++; 
+  
+                // if sum is greater than zero than 
+                // decrement in right side 
+                else
+                    r--; 
+            }
+                
+        }
+        return res;
+    }
+};