Competitive Programming Guide - Math #18 - Impartial Games #1

Problem: https://cses.fi/problemset/task/1729 Easy DP once you have the idea. If you understand the example, you should be able to solve the problem. The key idea is that a position is winning iff there is a move to a losing position (losing for the other player). This gives us a recurrence we can use to determine whether each position is winning or losing. This is the beginning of a mini-series on https://en.wikipedia.org/wiki/Impartial_game