KöMaL 2025 B5492
Kornél thinks about a closed subinterval of (where is a positive integer) with integer endpoints and length at least . Kristóf can ask the following question: he can choose an arbitrary closed subinterval with integer length, but not necessarily integer endpoints, and Kornél tells him the length of the intersection of the interval he picked and the interval chosen by Kristóf. (The answer is if the intersection of the two intervals is empty or consists of a single point.) Find the smallest number of questions with which Kristóf can guess the interval chosen by Kornél in all cases.
Official text KöMaL. Quoted with source.
Solutions
No solution is on olymmath yet. Official and human solutions come first when they arrive. AI solutions come after them, with a label.
Similar problems
These problems have the most words in common with this statement.