Longest Harmonious Subsequence

Problem

We define a harmonious array as an array where the difference between its maximum value and its minimum value is exactly 1.

Given an integer array nums, return the length of its longest harmonious subsequence among all its possible subsequences.

A subsequence of array is a sequence that can be derived from the array by deleting some or no elements without changing the order of the remaining elements.

Constraints

• 1 <= nums.length <= 2 * 104
• -109 <= nums[i] <= 109

Solution

The problem Longest Harmonious Subsequence can be solved by sorting the given array and finding the maximum length of consecutive elements with a value difference of 1.

Implementation

class Solution
{
  public:
    int findLHS(vector<int> &nums)
    {
        int ret = 0;
        sort(nums.begin(), nums.end());

        int left = 0, right = 0;
        while (right < nums.size())
        {
            if (nums[left] + 1 < nums[right])
                left += 1;
            else
            {
                if (nums[left] + 1 == nums[right])
                    ret = max(ret, right - left + 1);
                right += 1;
            }
        }

        return ret;
    }
};