How do you solve Minimum Operations to Make Array Values Equal to K on LeetCode?

Minimum Operations to Make Array Values Equal to K (LeetCode #3375) can be solved using Brute Force or Optimal Solution. The optimal approach is Optimal Solution with O(n) time complexity and O(n) space complexity. Key insight: We can only reduce numbers greater than k.

What is the brute force solution for Minimum Operations to Make Array Values Equal to K?

The brute force approach for Minimum Operations to Make Array Values Equal to K is Brute Force, with O(n²) time complexity and O(1) space complexity. The brute force approach involves trying every possible valid integer h that is less than or equal to the maximum value in the array. For each valid h, we count how many operations are needed to make all elements equal to k. The optimal Optimal Solution approach improves this to O(n).

What algorithm or data structure is used to solve Minimum Operations to Make Array Values Equal to K?

Minimum Operations to Make Array Values Equal to K uses the following concepts: Array, Hash Table. The recommended patterns to study are: Hash Map, Array.

What are the interview tips for Minimum Operations to Make Array Values Equal to K?

Always consider edge cases first. Explain your thought process clearly as you write code. Use comments to clarify complex logic.

What are common mistakes when solving Minimum Operations to Make Array Values Equal to K?

Not checking if any number is less than k early on. Overlooking the need to count operations correctly.

#3375

Minimum Operations to Make Array Values Equal to K

Easy

ArrayHash TableHash MapArray

LeetCode ↗

Approaches

Brute ForceOptimal

Complexity Comparison

	Brute Force	Optimal Solution★
Time	O(n²)	O(n)
Space	O(1)	O(n)

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Intuition

Time O(n)Space O(n)

The optimal solution takes advantage of the fact that we can directly count how many operations are needed by focusing on the unique values in the array. We only need to consider values greater than k and how many operations it takes to reduce them to k.

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Algorithm

5 steps

1Step 1: Create a frequency map of the numbers in nums.
2Step 2: If any number in nums is less than k, return -1 immediately.
3Step 3: Initialize operations to 0 and iterate through the unique values in descending order.
4Step 4: For each value greater than k, add its frequency to operations.
5Step 5: Return the total operations.

solution.py12 lines

1# Full working Python code
2
3def min_operations(nums, k):
4    from collections import Counter
5    freq = Counter(nums)
6    if any(num < k for num in nums):
7        return -1
8    operations = 0
9    for num in sorted(freq.keys(), reverse=True):
10        if num > k:
11            operations += freq[num]
12    return operations

ℹ

Complexity note: The complexity is O(n) because we traverse the array a couple of times (once for frequency counting and once for calculating operations), leading to linear time complexity.

1We can only reduce numbers greater than k.
2If any number is less than k, it's impossible to make all equal to k.

Solutions and explanations are original Tejav content. Problem titles © LeetCode — use the LeetCode button above for the full problem statement.