custodians in rooms of gallery, where the plan is like a chessboard (juniors)
Source: Tuymaada Olympiad 2019 junior p3
July 22, 2019
combinatoricsminimum valueminimumChessboard
Problem Statement
The plan of a picture gallery is a chequered figure where each square is a room, and every room can be reached from each other by moving to rooms adjacent by side. A custodian in a room can watch all the rooms that can be reached from this room by one move of a chess rook (without leaving the gallery). What minimum number of custodians is sufficient to watch all the rooms in every gallery of rooms ()?