MathDB
2021 Combo #6: Light pulse partitions

Source:

May 30, 2021
Combo

Problem Statement

A light pulse starts at a corner of a reflective square. It bounces around inside the square, reflecting off of the square’s perimeter nn times before ending in a different corner. The path of the light pulse, when traced, divides the square into exactly 20212021 regions. Compute the smallest possible value of nn.