2021 Combo Div 2 P1
Source:
March 2, 2021
combinatorics
Problem Statement
We have a by chessboard with kings (which can move to any of adjacent squares) in the bottom row. What is the minimum number of moves, if two pieces cannot occupy the same square at the same time, to move all the kings into an shape (a region where there are kings along each diagonal of the , as shown below)? \begin{tabular}{ c c c c c }
O & & & & O \\
& O & & O & \\
& & O & & \\
& O & & O & \\
O & & & & O \\
\end{tabular}Proposed by David Tang