# 594. Longest Harmonious Subsequence 最长和谐子序列

@TOC

## # 题目描述

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.

## # 解题方法

### # 统计次数

``````from collections import Counter
class Solution(object):
def findLHS(self, nums):
"""
:type nums: List[int]
:rtype: int
"""
counter = Counter(nums)
nums_set = set(nums)
longest = 0
for num in nums_set:
if num + 1 in counter:
longest = max(longest, counter[num] + counter[num + 1])
return longest
``````

``````class Solution(object):
def findLHS(self, nums):
"""
:type nums: List[int]
:rtype: int
"""
count = collections.Counter(nums)
res = 0
for num in count.keys():
if num + 1 in count:
res = max(res, count[num] + count[num + 1])
return res
``````

C++代码如下：

``````class Solution {
public:
int findLHS(vector<int>& nums) {
map<int, int> d;
for (int n : nums) d[n] ++;
int res = 0;
for (auto n : d) {
if (d.count(n.first + 1))
res = max(res, n.second + d[n.first + 1]);
}
return res;
}
};
``````

## # 日期

2018 年 2 月 1 日 2018 年 11 月 19 日 —— 周一又开始了 2018 年 12 月 7 日 —— 恩，12月又过去一周了