Leetcode 594. Longest Harmonious Subsequence Python

最新推荐文章于 2025-05-12 19:20:32 发布

chelseajcole

最新推荐文章于 2025-05-12 19:20:32 发布

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本文链接：https://blog.youkuaiyun.com/chelseajcole/article/details/98043999

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本文探讨了如何在给定整数数组中寻找最长和谐子序列的问题，和谐子序列定义为最大值与最小值之差恰好为1的子序列。通过两种方法进行解析：暴力解法和使用哈希表优化，后者显著提高了效率。

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594. Longest Harmonious Subsequence

We define a harmounious array as an array where the difference between its maximum value and its minimum value is exactly 1.

Now, given an integer array, you need to find the length of its longest harmonious subsequence among all its possible subsequences.

Example 1:

Input: [1,3,2,2,5,2,3,7]
Output: 5
Explanation: The longest harmonious subsequence is [3,2,2,2,3].

Python Brute Force:

class Solution:
    def findLHS(self, nums: List[int]) -> int:
        nums.sort()
        res=0
        for i in range(len(nums)):
            for j in range(i+1,len(nums)):
                if nums[j] == nums[i]:
                    continue
                elif nums[i] + 1 == nums[j]:
                    res=max(res,j-i+1)
        return res

TLE.

Using HashTable:

class Solution:
    def findLHS(self, nums: List[int]) -> int:
        d={}
        for i in nums:
            d[i] = d.get(i,0) + 1
        res=0
        for k in d:
            if k+1 in d:
                res=max(res,d[k]+d[k+1])
        return res