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58 lines
1.1 KiB
Python
58 lines
1.1 KiB
Python
"""
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128. Longest Consecutive Sequence
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Difficulty: Medium
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https://leetcode.com/problems/longest-consecutive-sequence/
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──────────────────────────────────────────────────
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Given an unsorted array of integers nums, return the length of the
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longest consecutive elements sequence.
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You must write an algorithm that runs in O(n) time.
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Example 1:
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Input: nums = [100,4,200,1,3,2]
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Output: 4
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Explanation: The longest consecutive elements sequence is [1, 2, 3,
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4]. Therefore its length is 4.
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Example 2:
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Input: nums = [0,3,7,2,5,8,4,6,0,1]
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Output: 9
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Example 3:
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Input: nums = [1,0,1,2]
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Output: 3
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Constraints:
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• 0 <= nums.length <= 10^5
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• -10^9 <= nums[i] <= 10^9
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"""
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class Solution:
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def longestConsecutive(self, nums: list[int]) -> int:
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seen = set(nums)
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best = 0
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for n in seen:
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if n - 1 in seen:
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continue
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length = 1
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while length + n in seen:
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length += 1
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best = max(length, best)
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return best
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