Merge pull request #112 from Shrishti-2002/main

Added Leedcode problem-15(3sum) in cpp

Coding Platforms(codechef,codeforces,etc)/LeetCode/3sum.cpp

@@ -0,0 +1,29 @@
+class Solution {
+public:
+    bool search(vector<int> v,int i,int j,int ele){
+        for(int p=i+1;p<j;p++){
+            if(v[p]==ele) return true;
+        }
+        return false;
+    }
+    vector<vector<int>> threeSum(vector<int>& nums) {
+        vector<vector<int>> v;
+        int n=nums.size();
+        if(n==0) return {};
+
+        sort(nums.begin(),nums.end());
+
+        for(int i=0;i<n-2;i++){
+            if(i>0 && nums[i]==nums[i-1]) continue;
+            for(int j=n-1;j>=(i+2);j--){
+                if(j<(n-1)&& nums[j]==nums[j+1]) continue;
+                int ele=(nums[i]+nums[j])*(-1);
+                if(ele>nums[j]) break;
+                if(binary_search(nums.begin()+i+1,nums.begin()+j,ele)) {
+                    v.push_back({nums[i],ele,nums[j]});
+                }
+            }
+        }
+        return v;
+    }
+};