2025-04-09 Daily Challenge

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In: DailyChallenge

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

April LeetCoding Challenge 9

Description

Minimum Operations to Make Array Values Equal to K

You are given an integer array nums and an integer k.

An integer h is called valid if all values in the array that are strictly greater than h are identical.

For example, if nums = [10, 8, 10, 8], a valid integer is h = 9 because all nums[i] > 9 are equal to 10, but 5 is not a valid integer.

You are allowed to perform the following operation on nums:

  • Select an integer h that is valid for the current values in nums.
  • For each index i where nums[i] > h, set nums[i] to h.

Return the minimum number of operations required to make every element in nums equal to k. If it is impossible to make all elements equal to k, return -1.

 

Example 1:

Input: nums = [5,2,5,4,5], k = 2

Output: 2

Explanation:

The operations can be performed in order using valid integers 4 and then 2.

Example 2:

Input: nums = [2,1,2], k = 2

Output: -1

Explanation:

It is impossible to make all the values equal to 2.

Example 3:

Input: nums = [9,7,5,3], k = 1

Output: 4

Explanation:

The operations can be performed using valid integers in the order 7, 5, 3, and 1.

 

Constraints:

  • 1 <= nums.length <= 100
  • 1 <= nums[i] <= 100
  • 1 <= k <= 100

Solution

class Solution {
public:
  int minOperations(vector<int>& nums, int k) {
    map<int, int> count;
    for(auto n : nums) {
      if(n < k) return -1;
      count[n] += 1;
    }
    return count.size() - (count.begin()->first == k);
  }
};

// Accepted
// 969/969 cases passed (13 ms)
// Your runtime beats 41.51 % of cpp submissions
// Your memory usage beats 11.32 % of cpp submissions (32.6 MB)
Algorithm