FastPrep
Problem · Array

Minimum Steps to Reduce Array Elements to 0

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Problem statement

You are given an integer array, and your task is to perform a series of operations to make all elements in the array equal to 0.

Operation Details:

  • In one operation, you can select any prefix of the array.
  • You can then increment or decrement all elements in the selected prefix by 1.

    • You are given an array arr consisting of n integers. Your task is to determine the minimum number of operations required to convert every element in the array to 0.

    A prefix is defined as a contiguous group of items that includes the first element in the cart. For example, [1], [1, 2], [1, 2, 3] etc are prefixes of [1, 2, 3, 4, 5].

    It is guaranteed that it is always possible to convert every element of the given array to 0 using the allowed operations.

    ✎﹏Credit to ⟡ Sndix ⟡ 🦋

    Function

    minimumStepsToReduceToZero(arr: int[]) → int

    Examples

    Example 1

    arr = [3, 2, 1]return = 3
    For the input arr, the most efficient approach is:
  • Operation 1: Let the prefix length be 2, and decrement by 1. Cart after this operation is [2, 1, 1]
  • Operation 2: Let the prefix length be 1, and decrement by 1. Cart after this operation is [1, 1, 1]
  • Operation 3: Let the prefix length be 3, and decrement by 1. Cart after this operation is [0, 0, 0]
    • So the enswer is 3. Note that it is not possible to make all the elements of the arry 0 in fewer operations.

    Constraints

    Unknown for now

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    public int minimumStepsToReduceToZero(int[] arr) {
  // write your code here
}
    arr[3, 2, 1]
    expected3
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