2025-06-30 Daily Challenge

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In: DailyChallenge

Today I have done leetcode's June LeetCoding Challenge with cpp.

June LeetCoding Challenge 30

Description

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.

 

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

Explanation:

The longest harmonious subsequences are [1,2], [2,3], and [3,4], all of which have a length of 2.

Example 3:

Input: nums = [1,1,1,1]

Output: 0

Explanation:

No harmonic subsequence exists.

 

Constraints:

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

Solution

class Solution {
public:
  int findLHS(vector<int>& nums) {
    map<int, int> count;
    for(auto n : nums) count[n] += 1;
    int answer = 0;
    for(auto [n, c] : count) {
      if(count.count(n + 1)) answer = max(answer, count[n] + count[n + 1]);
    }
    return answer;
  }
};

// Accepted
// 206/206 cases passed (58 ms)
// Your runtime beats 7.95 % of cpp submissions
// Your memory usage beats 16.24 % of cpp submissions (45.5 MB)
Algorithm