add 3sum

Author: rivkode

3sum/rivkode.py

@@ -1,5 +1,43 @@
 from typing import List, Tuple, Set
 
+class Solution(object):
+    def threeSum(self, nums):
+        result = set()
+        v_set = {}
+
+        for i, v in enumerate(nums):
+            v_set[v] = i
+
+        n = len(nums)
+        for i in range(n):
+            for j in range(i + 1, n):
+                v = nums[i]
+                w = nums[j]
+                target = -(v + w)
+                if target in v_set:
+                    k = v_set[target]
+                    if k != i and k != j:
+                        triplet = tuple(sorted([v, w, target]))
+                        result.add(triplet)
+
+        return list(result)
+
+if __name__ == "__main__":
+    solution = Solution()
+    nums = [-1,0,1,2,-1,-4]
+    result = solution.threeSum(nums)
+    print(result)
+
+
+
+
+
+        
+        
+
+
+# previous version
+
 # threeSum3()
 # Time Complexity O(n ^ 2)
 # - when sorting by sorted function(TimSort) for each string it takes O(nlogn)
@@ -8,58 +46,60 @@
 # - when sorting takes O(1)
 
 
-class Solution:
-    def threeSum(self, nums: List[int]) -> list[tuple[int, ...]]:
-
-        triplets = set()
-        for i in range(len(nums) - 2):
-            for j in range(i + 1, len(nums)):
-                for k in range(j + 1, len(nums)):
-                    if nums[i] + nums[j] + nums[k] == 0:
-                        triplet = [nums[i], nums[j], nums[k]]
-                        triplets.add(tuple(sorted(triplet)))
-
-        return list(triplets)
-
-    def threeSum2(self, nums: List[int]) -> list[tuple[int, ...]]:
-        triplets = set()
-
-        for i in range(len(nums)):
-            seen = set()
-            for j in range(i + 1, len(nums)):
-                res = -(nums[i] + nums[j])
-                if res in seen:
-                    triplet = [nums[i], nums[j], res]
-                    triplets.add(tuple(sorted(triplet)))
-                seen.add(nums[j])
-
-        return list(triplets)
-
-    def threeSum3(self, nums: List[int]) -> list(tuple[int, ...]):
-        triplets = set()
-        nums.sort()
-
-        for i in range(len(nums) - 2):
-            l = i + 1
-            r = len(nums) - 1
-
-            while l < r:
-                res = nums[l] + nums[r] + nums[i]
-                if res > 0:
-                    r -= 1
-                elif res < 0:
-                    l += 1
-                elif res == 0:
-                    triple = (nums[l], nums[r], nums[i])
-                    triplets.add(triple)
-                    l, r = l + 1, r - 1
-                else:
-                    raise Exception
-        return list(triplets)
+# class Solution:
+#     def threeSum(self, nums: List[int]) -> list[tuple[int, ...]]:
 
-if __name__ == "__main__":
-    nums = [-1,0,1,2,-1,-4]
+#         triplets = set()
+#         for i in range(len(nums) - 2):
+#             for j in range(i + 1, len(nums)):
+#                 for k in range(j + 1, len(nums)):
+#                     if nums[i] + nums[j] + nums[k] == 0:
+#                         triplet = [nums[i], nums[j], nums[k]]
+#                         triplets.add(tuple(sorted(triplet)))
+
+#         return list(triplets)
+
+#     def threeSum2(self, nums: List[int]) -> list[tuple[int, ...]]:
+#         triplets = set()
+
+#         for i in range(len(nums)):
+#             seen = set()
+#             for j in range(i + 1, len(nums)):
+#                 res = -(nums[i] + nums[j])
+#                 if res in seen:
+#                     triplet = [nums[i], nums[j], res]
+#                     triplets.add(tuple(sorted(triplet)))
+#                 seen.add(nums[j])
+
+#         return list(triplets)
+
+#     def threeSum3(self, nums: List[int]) -> list(tuple[int, ...]):
+#         triplets = set()
+#         nums.sort()
+
+#         for i in range(len(nums) - 2):
+#             l = i + 1
+#             r = len(nums) - 1
+
+#             while l < r:
+#                 res = nums[l] + nums[r] + nums[i]
+#                 if res > 0:
+#                     r -= 1
+#                 elif res < 0:
+#                     l += 1
+#                 elif res == 0:
+#                     triple = (nums[l], nums[r], nums[i])
+#                     triplets.add(triple)
+#                     l, r = l + 1, r - 1
+#                 else:
+#                     raise Exception
+#         return list(triplets)
+
+# if __name__ == "__main__":
+#     nums = [-1,0,1,2,-1,-4]
+
+
+#     solution = Solution()
+#     solution.threeSum3(nums)
 
 
-    solution = Solution()
-    solution.threeSum3(nums)