Minimum Number of Increments on Subarrays to Form a Target Array

Ah, the classic problem of trying to make a target array by incrementing subarrays. It’s like trying to convince your friends to go on a diet while you’re munching on a pizza. You know it’s going to be a struggle, but hey, at least you’re trying!

Imagine you have a group of friends who all want to reach a certain height. Some are short, some are tall, and some are just… well, they’re still growing. The goal is to make everyone the same height without using any magic potions. You can only increase their heights in groups (subarrays), and you want to do it with the least amount of effort. Sounds fun, right?

Language Links

Code Solution


class Solution:
    def minNumberOperations(self, target: list[int]) -> int:
        ans = target[0]

        for a, b in zip(target, target[1:]):
            if a < b:
                ans += b - a

        return ans

Approach

The code starts by initializing the answer with the first element of the target array. Then, it iterates through the array, comparing each element with the next one. If the next element is greater, it adds the difference to the answer. This way, it calculates the minimum number of increments needed to make the array match the target.

Time and Space Complexity

Complexity Type	Complexity
Time Complexity	O(n), where n is the length of the target array. We only loop through the array once.
Space Complexity	O(1), as we are using a constant amount of space for the variables.

Real-World Example

Let’s say you’re at a party, and everyone is trying to reach the same level of fun (height). You start with a few friends who are already having a blast (the initial heights). As the night goes on, some friends start to have more fun (the increments), and you need to figure out how to get everyone to that same level of fun without leaving anyone behind. The solution is to keep track of how much fun each friend needs to catch up!