[LeetCode]594. Longest Harmonious Subsequence

题目

We define a harmonious array is 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].

Note: The length of the input array will not exceed 20,000.

难度

Easy

方法

用一个map存放所有值出现的次数，对于map中的每个num，求出num和num+1出现的次数之和，找出最大值即可

python代码

class Solution(object):
    def findLHS(self, nums):
        """
        :type nums: List[int]
        :rtype: int
        """
        nums_count = {}
        for num in nums:
            nums_count[num] = nums_count.get(num, 0) + 1

        result = 0
        for num in nums_count:
            count = nums_count[num]
            if nums_count.get(num+1):
                result = max(result, count + nums_count[num+1])
        return result

assert Solution().findLHS([1,3,2,2,5,2,3,7]) == 5