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| 1 | +# 594. 最长和谐子序列 |
| 2 | + |
| 3 | + |
| 4 | +[url](https://leetcode-cn.com/problems/longest-harmonious-subsequence/) |
| 5 | + |
| 6 | + |
| 7 | +## 题目 |
| 8 | +和谐数组是指一个数组里元素的最大值和最小值之间的差别 正好是 1 。 |
| 9 | + |
| 10 | +现在，给你一个整数数组 nums ，请你在所有可能的子序列中找到最长的和谐子序列的长度。 |
| 11 | + |
| 12 | +数组的子序列是一个由数组派生出来的序列，它可以通过删除一些元素或不删除元素、且不改变其余元素的顺序而得到。 |
| 13 | + |
| 14 | + |
| 15 | + |
| 16 | +``` |
| 17 | +输入：nums = [1,3,2,2,5,2,3,7] |
| 18 | +输出：5 |
| 19 | +解释：最长的和谐子序列是 [3,2,2,2,3] |
| 20 | +输入：nums = [1,2,3,4] |
| 21 | +输出：2 |
| 22 | +输入：nums = [1,1,1,1] |
| 23 | +输出：0 |
| 24 | +``` |
| 25 | +返回 true，因为 t 与 s 的一个子树拥有相同的结构和节点值。 |
| 26 | + |
| 27 | +## 方法 |
| 28 | + |
| 29 | + |
| 30 | +## code |
| 31 | + |
| 32 | +### js |
| 33 | + |
| 34 | +```js |
| 35 | +let findLHS = nums => { |
| 36 | + let map = new Map(); |
| 37 | + nums.forEach(num => { |
| 38 | + if (map.has(num)) { |
| 39 | + map.set(num, map.get(num) + 1); |
| 40 | + } else { |
| 41 | + map.set(num , 1); |
| 42 | + } |
| 43 | + }); |
| 44 | + let longest = 0; |
| 45 | + for (const key of map.keys()) { |
| 46 | + if (map.has(key + 1)) { |
| 47 | + longest = Math.max(longest, map.get(key + 1) + map.get(key)); |
| 48 | + } |
| 49 | + } |
| 50 | + return longest; |
| 51 | +}; |
| 52 | +console.log(findLHS([1,3,2,2,5,2,3,7])) |
| 53 | +``` |
| 54 | + |
| 55 | +### go |
| 56 | + |
| 57 | +```go |
| 58 | +func findLHS(nums []int) int { |
| 59 | + m := make(map[int]int, len(nums)) |
| 60 | + for _, num := range nums { |
| 61 | + if v, ok := m[num]; ok { |
| 62 | + m[num] = v + 1 |
| 63 | + } else { |
| 64 | + m[num] = 1 |
| 65 | + } |
| 66 | + } |
| 67 | + longest := 0 |
| 68 | + for _, k := range m { |
| 69 | + if v, ok := m[k + 1]; ok { |
| 70 | + longest = max3(longest, v + m[k]) |
| 71 | + } |
| 72 | + } |
| 73 | + return longest |
| 74 | +} |
| 75 | +func max3(a int , b int) int { |
| 76 | + if a > b { |
| 77 | + return a |
| 78 | + } else { |
| 79 | + return b |
| 80 | + } |
| 81 | +} |
| 82 | +``` |
| 83 | + |
| 84 | +### java |
| 85 | + |
| 86 | +```java |
| 87 | +class Solution { |
| 88 | + public int findLHS(int[] nums) { |
| 89 | + Map<Integer, Integer> map = new HashMap<>(); |
| 90 | + for (int num : nums) { |
| 91 | + map.put(num, map.getOrDefault(num, 0) + 1); |
| 92 | + } |
| 93 | + int longest = 0; |
| 94 | + for (int num : map.keySet()) { |
| 95 | + if (map.containsKey(num + 1)) { |
| 96 | + longest = Math.max(longest, map.get(num + 1) + map.get(num)); |
| 97 | + } |
| 98 | + } |
| 99 | + return longest; |
| 100 | + } |
| 101 | +} |
| 102 | +``` |
| 103 | + |
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