SUDOKU 200 Challenging puzzles with answers Book 6

Solving a Sudoku game is a combinatorial task of intermediate complexity. The g nerai problem of filling in an incompl te n 2 x n 2 grid with n x n subgrids belongs to the class of NP-complete problems. Th se problems are conjectured to increase in computational complexity at an exponential rate in n. Nonetheless, a well planned exhaustive search can work quite well for a low value of n such as 9. For larger values of n, brute force, no matter how cleverly executed, is simply not an option. In contrast, simulated annealing and alternating projections may yield good approximate solutions and partially salvage the situation.