594. Longest Harmonious Subsequence

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].

题目含义：如果一个数组中最大值和最小值相差为1，我们称这个数组为harmonious数组。现在给定一个数组，求出最长的harmonious数组长度。
其实也就是求最大值和最小值之间相差1的最长子序列的长度。

    public int findLHS(int[] nums) {
        if (nums.length == 0) return 0;
        Map<Integer, Integer> map = new HashMap<>();
        for (int i = 0; i < nums.length; i++) {
            map.put(nums[i], map.getOrDefault(nums[i], 0) + 1);
        }
        int result = 0;
        for (Integer key : map.keySet()) {
            if (map.containsKey(key + 1)) {
                result = Math.max(result, map.get(key) + map.get(key + 1));
            }
        }
        return result;        
    }