Minimum Number of Increments on Subarrays to Form a Target Array

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Question

Approach

My approach is to track how many times the array increases. I start by setting the number of operations to the first element since that’s how many increments are needed to reach it from zero. Then, as I move through the array, I only add the positive differences between consecutive elements—because whenever a value increases compared to the previous one, that increase represents new operations needed. This gives the minimum number of operations efficiently in one pass.

Implementation

class Solution:
    def minNumberOperations(self, target: List[int]) -> int:
        operations = target[0]
        for i in range(1, len(target)):
            if target[i] > target[i - 1]:
                operations += target[i] - target[i - 1]
        return operations

Complexities

• Time: O(n)
• Space: O(1)