From 1fd8182be534fe3bc80efbd870f947ccd8f24825 Mon Sep 17 00:00:00 2001
From: Fazeel Usmani <fazeelusmani18@gmail.com>
Date: Thu, 28 Oct 2021 20:57:04 +0530
Subject: [PATCH] Create 28_3sum.cpp

---
 .../28_3sum.cpp                               | 25 +++++++++++++++++++
 1 file changed, 25 insertions(+)
 create mode 100644 10 October LeetCode Challenge 2021/28_3sum.cpp

diff --git a/10 October LeetCode Challenge 2021/28_3sum.cpp b/10 October LeetCode Challenge 2021/28_3sum.cpp
new file mode 100644
index 0000000..12f5799
--- /dev/null
+++ b/10 October LeetCode Challenge 2021/28_3sum.cpp	
@@ -0,0 +1,25 @@
+class Solution {
+public:
+    vector<vector<int>> threeSum(vector<int>& nums) {
+        unordered_map<int, int> m;
+        vector<vector<int>> res;
+       
+        sort(nums.begin(), nums.end());
+        
+        for (int i = 0; i < nums.size(); i++) 
+            m[nums[i]] = i;
+        
+        for (int i = 0; i < nums.size(); i++) {
+            if (i > 0 && nums[i] == nums[i-1]) continue;
+            
+            for (int j = i+1; j < nums.size(); j++) {
+                if (j != i+1 && nums[j] == nums[j-1]) continue;
+                
+                if (m[-(nums[i] + nums[j])] > j) 
+                    res.push_back({nums[i], nums[j], -(nums[i] + nums[j])});
+                
+            }
+        }
+        return res;
+    }
+};