From the above Call graph we can see that the program took no time in finding the solutionand the maximum number of calls were made to the checkRow, checkColumn and checkSquare function. However, to get a better understanding of the program let's try a harder Sudoku puzzle.

From the above Call graph we can see that time increased significantly for a harder Sudoku puzzle and almost 50% of the time is consumed by the checkRow function, 18.8% by checkColumn and finally 12% by the checkSquare function. Thousands of call were made for these 3 functions and if we parallelize them then the efficiency of the program will increase significantly. Therefore this is an ideal project for parallelizing.