[LeetCode] 594. Longest Harmonious Subsequence

Problem : https://leetcode.com/problems/longest-harmonious-subsequence/description/

Since we only need the length of the subsequence, we don't need to preserve the original order of the numbers. We can sort the origin array in non-decreasing order and use sliding window to find the longest subsequence.

The left pointer points to the minmum value and the right pointer points to the maximum value.

Move left pointer to right, when the difference is larger than 1.

Move right pointer to right, when the difference is smaller or equal to 1.

Update the longest subsequence length when the difference is equal to 1.

class Solution {
    public int findLHS(int[] nums) {
        Arrays.sort(nums);

        int left = 0; 
        int result = 0;
        for (int right = 0; right < nums.length;) {
            long diff = nums[right] - nums[left];
            if (diff < 1L) {
                right++;
                continue;
            }
            if (diff == 1L) {
                result = Math.max(result, right - left + 1);
                right++;
                continue;
            }
            left += 1;
        }
        
        return result;
    }