Refactor : 3sum

Author: printjin-gmailcom

3sum/printjin-gmailcom.py

@@ -1,14 +1,16 @@
-from typing import List
-from itertools import combinations
 class Solution:
-    def threeSum(self, nums):
-        res = set()
-        n = len(nums)
-        for i in range(n):
-            a = nums[i]
-            rest = nums[:i] + nums[i+1:] 
-            for comb in combinations(rest, 2):
-                if sum(comb) == -a:
-                    triplet = tuple(sorted([a, *comb]))
-                    res.add(triplet)
-        return [list(t) for t in res]
+    def threeSum(self, nums: List[int]) -> List[List[int]]:
+        triplets = set()
+        nums.sort()
+        for i in range(len(nums) - 2):
+            low, high = i + 1, len(nums) - 1
+            while low < high:
+                three_sum = nums[i] + nums[low] + nums[high]
+                if three_sum < 0:
+                    low += 1
+                elif three_sum > 0:
+                    high -= 1
+                else:
+                    triplets.add((nums[i], nums[low], nums[high]))
+                    low, high = low + 1, high - 1
+        return list(triplets)