Tarifa

ID: tarifa

Difficulty: 1.3

CPU Time: 1 second

Memory: 1024 MB

Solution

Since the amounts carry over each month, and at worst there is none left over, we can simply keep a running total and at each month, add X (the per-month allotted data) minus the Ni, the amount used that month. To account for the additional amount allotted normally at the start of the Nth month, this total should be initialized to X, not zero.