From 2b0cfe42e342e8f90a0377212fad11900049f893 Mon Sep 17 00:00:00 2001
From: Anieshar1 <114723048+Anieshar1@users.noreply.github.com>
Date: Sat, 22 Oct 2022 12:08:30 +0530
Subject: [PATCH] Create 4sum.cpp

---
 4sum.cpp | 45 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)
 create mode 100644 4sum.cpp

diff --git a/4sum.cpp b/4sum.cpp
new file mode 100644
index 0000000..048e703
--- /dev/null
+++ b/4sum.cpp
@@ -0,0 +1,45 @@
+class Solution {
+public:
+    vector<vector<int>> fourSum(vector<int>& nums, int target) {
+      vector<vector<int>>res;
+      if(nums.size()<3)
+        return res;
+      
+      sort(nums.begin(),nums.end());
+      for(int i=0;i<nums.size();i++){
+        
+        if(i == 0 || (i != 0 && nums[i]!=nums[i-1])) {
+          
+           long long int  sum = target-nums[i];
+           
+           for(int j = i + 1; j < nums.size(); j++) {
+             
+             if(j==i+1 || nums[j] != nums[j-1]) {
+                int k = j + 1;
+                int l = nums.size()-1;
+                long long sum1 = sum - nums[j];
+                while(k < l) {
+                  if(nums[k] + nums[l] == sum1){
+                    res.push_back({nums[i],nums[j],nums[k],nums[l]});
+                    while(k<l && nums[k]==nums[k+1])
+                      k++;
+                    while(k<l && nums[l]==nums[l-1])
+                      l--;
+                    k++;
+                    l--;
+                  }
+                  else if( nums[k] + nums[l] > sum1){
+                    l--;
+                  }else{
+                    k++;
+                  }
+                }
+             }
+           }
+        }    
+      }
+      return res;
+
+        
+    }
+};