(Sudoku search animation) Modify Programming Exercise 22.21 to display the intermediate results of the search

(Sudoku search animation) Modify Programming Exercise 22.21 to display the intermediate results of the search. Figure 30.32 gives a snapshot of an animation in progress with number 2 placed in the cell in Figure 30.32a, number 3 placed in the cell in Figure 30.32b, and number 3 placed in the cell in Figure 30.32c. The animation displays all the search steps.

FIGURE 30.32 The intermediate search steps are displayed in the animation for the Sudoku problem.