Solved 241. 3Sum using Python code

Author: KwonNayeon

3sum/KwonNayeon.py

@@ -0,0 +1,42 @@
+"""
+Constraints:
+1. 3 <= nums.length <= 3000
+2. -10^5 <= nums[i] <= 10^5
+
+Time Complexity:
+    - O(n^2) (정렬은 O(n log n), 이중 반복문은 O(n^2))
+Space Complexity:
+    - O(n) (결과 리스트)
+"""
+
+class Solution:
+    def threeSum(self, nums: List[int]) -> List[List[int]]:
+        nums.sort()
+        result = []
+
+        for i in range(len(nums) - 2):
+            if i > 0 and nums[i] == nums[i-1]:
+                continue
+
+            left, right = i+1, len(nums)-1
+
+            while left < right:
+                sum = nums[i] + nums[left] + nums[right]
+
+                if 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 sum < 0:
+                    left += 1
+                else:
+                    right -= 1
+    
+        return result