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Author: jasoncao11

43. 最长连续序列.md

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+***给定一个未排序的整数数组 nums ，找出数字连续的最长序列（不要求序列元素在原数组中连续）的长度。请你设计并实现时间复杂度为 O(n) 的算法解决此问题。***
+
+Ref: https://leetcode.cn/problems/longest-consecutive-sequence/solution/zui-chang-lian-xu-xu-lie-by-leetcode-solution/
+![algo24](./images/algo24.jpg)
+
+```
+class Solution:
+    def longestConsecutive(self, nums: List[int]) -> int:
+        longest_streak = 0
+        num_set = set(nums)
+        for num in num_set:
+            if num - 1 not in num_set:
+                current_num = num
+                current_streak = 1
+                while current_num + 1 in num_set:
+                    current_num += 1
+                    current_streak += 1
+                longest_streak = max(longest_streak, current_streak)
+        return longest_streak
+```