Merge pull request #427 from Abhiroop-Singh/Abhiroop

Add 3Sum Problem to CPP Folder

Author: gantavyamalviya

CPP/Problems/Leetcode 15-3SumProblem.cpp

@@ -0,0 +1,45 @@
+// Problem link:https://leetcode.com/problems/3sum/description/
+
+class Solution {
+public:
+    vector<vector<int>> threeSum(vector<int>& nums) {
+        sort(nums.begin(),nums.end());
+        int n=nums.size();
+        vector<vector<int>> ans;
+        set<vector<int>> st;
+        for(int i=0;i<n;i++){
+            vector<int> check;
+            int find=-(nums[i]);
+            int l=i+1,r=n-1;
+            while(r>l){
+                int sum=(nums[l]+nums[r]);
+                if(sum==find){ 
+                    check.push_back(nums[i]);
+                    check.push_back(nums[l]);
+                    check.push_back(nums[r]);
+                    st.insert(check);
+                    if(check.size()==3){
+                        check.clear();
+                    }
+                    l++;r--;
+                }
+                else if(sum>find){
+                    r--;
+                }
+                else{
+                    l++;
+                }
+            }
+        }
+        
+        for(auto el:st){
+        vector<int> check1;
+            for(int i=0;i<el.size();i++){
+                check1.push_back(el[i]);
+            }
+            ans.push_back(check1);
+        }
+        return ans;
+
+    }
+};