Code RoomMake array non-decreasing
HardPrep Room Coding #1059

Make array non-decreasing

CodingAlgorithms & data structuresSenior–Staff~35 min

Given an integer array `a`, you may increment or decrement any element by 1 at a cost of 1 per unit. Find the minimum total cost to make the array non-decreasing (a[0] <= a[1] <= ... <= a[n-1]). Return that minimum cost.

Implement
min_cost_non_decreasing(a: list[int]) → int
Examples
in[[3,2,1]]out2
What a strong answer looks like

State your approach and its time/space complexity out loud before you optimize. Handle the edge cases (empty input, duplicates, overflow), and say why you chose this over the brute force. Green tests are the floor, not the grade.

0:00 of about 35 min
InputExpectedGot
[[3,2,1]]2not run yetsample