4 solved

Author: devyulbae

3sum/devyulbae.py

@@ -0,0 +1,40 @@
+"""
+Blind 75 - LeetCode Problem 15. 3Sum
+https://leetcode.com/problems/3sum/
+시간복잡도 O(n^2)
+"""
+from typing import List
+
+class Solution:
+    def threeSum(self, nums: List[int]) -> List[List[int]]:
+        nums.sort()
+        answer = []
+        n = len(nums)
+
+        for i in range(n):
+            if i > 0 and nums[i] == nums[i - 1]:
+                continue  # 중복 원소 스킵
+
+            left, right = i + 1, n - 1
+            while left < right:
+                total = nums[i] + nums[left] + nums[right]
+
+                if total == 0:
+                    answer.append([nums[i], nums[left], nums[right]])
+                    left += 1
+                    right -= 1
+
+                    # 중복값 건너뛰기
+                    while left < right and nums[left] == nums[left - 1]:
+                        left += 1
+                    while left < right and nums[right] == nums[right + 1]:
+                        right -= 1
+
+                elif total < 0:
+                    left += 1  # 합이 작으니 left를 키워야 함
+
+                else:
+                    right -= 1  # 합이 크니 right를 줄여야 함
+
+        return answer
+