The function solve maze(maze, r0,c0,r, c) takes a maze, the position of a starting square (r0,c0), and the position of a target square (r, c), and returns a path from the starting square to the target square. the maze is given as a matrix, where each entry is a four-bit binary integer (b3,b2,b1,b0) that indicates how the corresponding square is connected to its neighboring squares: b0 is 1 if the square is connected to the left; b1 indicates if the square is connected to the right; b2 indicates if the square is connected to the above; b3 indicates if the square is connected to the below. for example, in the following maze, the square at (1,1) is represented by the binary number 1010 (i. e., the decimal number 10), meaning that the square is connected to the right and the blow.