adding 3sum

Author: daiyongg-kim

3sum/daiyongg-kim.py

@@ -0,0 +1,36 @@
+class Solution:
+    def threeSum(self, nums: List[int]) -> List[List[int]]:
+        nums.sort()
+
+        result = []
+        n = len(nums)
+
+        for i in range(n - 2):
+            
+            if i > 0 and nums[i] == nums[i - 1]:
+                continue
+            
+            left = i + 1  
+            right = n - 1 
+            while left < right:
+                current_sum = nums[i] + nums[left] + nums[right]
+
+                if current_sum == 0:
+                    result.append([nums[i], nums[left], nums[right]])
+
+                    while left < right and nums[left] == nums[left + 1]:
+                        left += 1
+
+                    while left < right and nums[right] == nums[right - 1]:
+                        right -= 1
+                        
+                    left += 1
+                    right -= 1
+                 
+                elif current_sum < 0:
+                    left += 1
+                
+                else: 
+                    right -= 1
+            
+        return result