2

lc_127.py

@@ -0,0 +1,42 @@
+import sys
+
+
+class Solution:
+    def __init__(self):
+        self.number_set: set[int] = set()  # 哈希表，全 O(1)
+        self.longest_length: int = 1
+
+    def longestConsecutive(self, nums: list[int]) -> int:
+        if not nums: return 0
+        self.number_set = set(nums)  # O(n)
+        for n in self.number_set:
+            # n = self.number_set.pop()
+            # print(n, file=sys.stderr)
+            current_length: int = 1
+            if n + 1 in self.number_set:
+                continue
+            # pointer = n
+            # while True:
+            #     if pointer + 1 in self.number_set:
+            #         pointer += 1
+            #         current_length += 1
+            #         self.number_set.remove(pointer)
+            #     else:
+            #         break
+            pointer = n
+            while True:
+                if pointer - 1 in self.number_set:
+                    pointer -= 1
+                    current_length += 1
+                    # self.number_set.remove(pointer)
+                else:
+                    break
+            self.longest_length = max(current_length, self.longest_length)
+
+        return self.longest_length
+
+
+if __name__ == '__main__':
+    sol = Solution()
+    print(sol.longestConsecutive([100, 4, 200, 1, 3, 2]))
+    print(sol.longestConsecutive([0, 3, 7, 2, 5, 8, 4, 6, 0, 1]))