Minimize Batch Processing Time | Dataford Interview Questions

At Stripe, an engineering team tracks repeated workload sizes in a batch job and wants to reduce processing overhead. Given an integer array tasks, return the minimum number of operations needed to remove all tasks, where one operation can remove either 2 equal values or 3 equal values.

If it is impossible to remove all tasks under these rules, return -1.

Formal Specification

Input: tasks — a list of integers
Output: An integer representing the minimum number of operations required to remove all elements, or -1 if no valid sequence exists

Constraints

1 <= len(tasks) <= 10^5
1 <= tasks[i] <= 10^9
Each operation removes exactly 2 or 3 equal values

Function Signature

def min_operations(tasks):

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