function [doors,opened,closed] = hundredDoors() %Initialize the doors, make them booleans for easy vectorization doors = logical( (1:1:100) ); %Go through the flipping process, ignore the 1 case because the doors %array is already initialized to all open for initialPosition = (2:100) doors(initialPosition:initialPosition:100) = not( doors(initialPosition:initialPosition:100) ); end opened = find(doors); %Stores the numbers of the open doors closed = find( not(doors) ); %Stores the numbers of the closed doors end