Algorithm
Problem Name: 594. Longest Harmonious Subsequence
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.
Example 1:
Input: nums = [1,3,2,2,5,2,3,7] Output: 5 Explanation: The longest harmonious subsequence is [3,2,2,2,3].
Example 2:
Input: nums = [1,2,3,4] Output: 2
Example 3:
Input: nums = [1,1,1,1] Output: 0
Constraints:
1 <= nums.length <= 2 * 104-109 <= nums[i] <= 109
Code Examples
#1 Code Example with Java Programming
Code -
Java Programming
class Solution {
public int findLHS(int[] nums) {
int maxSubarraySize = 0;
Map < Integer, Integer> map = new HashMap<>();
for (int num : nums) {
map.put(num, map.getOrDefault(num, 0) + 1);
if (map.containsKey(num + 1)) {
maxSubarraySize = Math.max(maxSubarraySize, map.get(num) + map.get(num + 1));
}
if (map.containsKey(num - 1)) {
maxSubarraySize = Math.max(maxSubarraySize, map.get(num) + map.get(num - 1));
}
}
return maxSubarraySize;
}
}
Input
Output
#2 Code Example with Javascript Programming
Code -
Javascript Programming
const findLHS = function(nums) {
if(nums == null) return 0
if(Object.prototype.toString.call(nums) === '[object Array]' && nums.length === 0) return 0
let res = 0
const map = {}
for (let el of nums) {
if(map.hasOwnProperty(el)) {
map[el] += 1
} else {
map[el] = 1
}
}
Object.keys(map).forEach(el => {
if(map.hasOwnProperty(+el + 1)) {
res = Math.max(res, map[el] + map[+el + 1])
}
})
console.log(res)
return res
};
Input
Output
#3 Code Example with C# Programming
Code -
C# Programming
using System;
using System.Collections.Generic;
namespace LeetCode
{
public class _0594_LongestHarmoniousSubsequence
{
public int FindLHS(int[] nums)
{
var counts = new Dictionary < int, int>();
var result = 0;
foreach (var num in nums)
{
if (!counts.ContainsKey(num))
counts[num] = 1;
else
counts[num]++;
}
foreach (var key in counts.Keys)
if (counts.ContainsKey(key + 1))
result = Math.Max(result, counts[key] + counts[key + 1]);
return result;
}
}
}
Input
Output