scale with only two stones allowed
Source: 239 2015 J 1
May 15, 2020
combinatorics
Problem Statement
There are 10 stones of different weights with distinct pairwise sums. We have a special two-tiered balance scale such that only two stones can be put on each cup and then we understand which cup is heavier. Prove that having this scale you can either find the heaviest or the lightest stone.