3sum

Author: changhyumm

3sum/changhyumm.py

@@ -0,0 +1,35 @@
+class Solution:
+    def threeSum(self, nums: List[int]) -> List[List[int]]:
+        # ans = set()
+        # for i in range(len(n)):
+        #     seen = {}
+        #     for j in range(i+1, len(n)):
+        #         complement = -(nums[i] + nums[j])
+        #         if complement in seen:
+        #             ans.add(tuple(sorted([nums[i], nums[j], complement])))
+        #         seen[nums[j]] = j
+        # return [list(triplet) for triplet in ans]
+        # hash + 이중 loop -> O(n^2)
+
+
+        ## 투포인터 활용
+        # sort + loop -> O(nlogn)
+        ans_set = set()
+        nums.sort()
+        for i in range(len(nums)):
+            l = i + 1
+            r = len(nums) - 1
+            while l < r:
+                total = nums[i] + nums[l] + nums[r]
+                if total < 0:
+                    l += 1
+                elif total > 0:
+                    r -= 1
+                else:
+                    # 중복제거
+                    ans_set.add((nums[i], nums[l], nums[r]))
+                    l += 1
+                    r -= 1
+        return list(ans_set)
+
+