4some👄

Author: sachuverma

Striver Sheet/Day-4/4Sum.cpp

@@ -0,0 +1,67 @@
+/*
+4Sum
+====
+
+Given an array nums of n integers, return an array of all the unique quadruplets [nums[a], nums[b], nums[c], nums[d]] such that:
+
+0 <= a, b, c, d < n
+a, b, c, and d are distinct.
+nums[a] + nums[b] + nums[c] + nums[d] == target
+You may return the answer in any order.
+
+Example 1:
+Input: nums = [1,0,-1,0,-2,2], target = 0
+Output: [[-2,-1,1,2],[-2,0,0,2],[-1,0,0,1]]
+
+Example 2:
+Input: nums = [2,2,2,2,2], target = 8
+Output: [[2,2,2,2]]
+
+Constraints:
+1 <= nums.length <= 200
+-109 <= nums[i] <= 109
+-109 <= target <= 109
+*/
+
+class Solution
+{
+public:
+  vector<vector<int>> fourSum(vector<int> &nums, int target)
+  {
+    int n = nums.size();
+    sort(nums.begin(), nums.end());
+    vector<vector<int>> ans;
+
+    for (int i = 0; i < n - 3; ++i)
+    {
+      for (int j = i + 1; j < n - 2; ++j)
+      {
+        int tar = target - nums[j] - nums[i];
+
+        int k = j + 1, l = n - 1;
+        while (k < l)
+        {
+          if (nums[k] + nums[l] == tar)
+          {
+            ans.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] < tar)
+            k++;
+          else
+            l--;
+        }
+        while (j < n - 2 && nums[j] == nums[j + 1])
+          j++;
+      }
+      while (i < n - 3 && nums[i] == nums[i + 1])
+        i++;
+    }
+    return ans;
+  }
+};

Striver Sheet/README.md

@@ -32,7 +32,7 @@
 ###
 
 - [Two Sum](https://leetcode.com/problems/two-sum/) - [Cpp Soultion](./Day-4/Two%20Sum.cpp)
-- []() - [Cpp Soultion](./Day-4/.cpp)
+- [4Sum](https://leetcode.com/problems/4sum/) - [Cpp Soultion](./Day-4/4Sum.cpp)
 - []() - [Cpp Soultion](./Day-4/.cpp)
 - []() - [Cpp Soultion](./Day-4/.cpp)
 - []() - [Cpp Soultion](./Day-4/.cpp)