2019 USAJMO Problems/Problem 1
Problem
There are bowls arranged in a row, number
through
, where
and
are given positive integers. Initially, each of the first
bowls contains an apple, and each of the last
bowls contains a pear.
A legal move consists of moving an apple from bowl to bowl
and a pear from bowl
to bowl
, provided that the difference
is even. We permit multiple fruits in the same bowl at the same time. The goal is to end up with the first
bowls each containing a pear and the last
bowls each containing an apple. Show that this is possible if and only if the product
is even.
Solution
The problems on this page are copyrighted by the Mathematical Association of America's American Mathematics Competitions.
See also
2019 USAJMO (Problems • Resources) | ||
First Problem | Followed by Problem 2 | |
1 • 2 • 3 • 4 • 5 • 6 | ||
All USAJMO Problems and Solutions |