MathDB
Operations on Pebbles

Source: ISL 2022 C6

July 9, 2023
combinatoricsIMO ShortlistAZE IMO TST

Problem Statement

Let nn be a positive integer. We start with nn piles of pebbles, each initially containing a single pebble. One can perform moves of the following form: choose two piles, take an equal number of pebbles from each pile and form a new pile out of these pebbles. Find (in terms of nn) the smallest number of nonempty piles that one can obtain by performing a finite sequence of moves of this form.