#include <iostream> using namespace std; char board[9][9]; int rs[9], cs[9], bs[9]; void set(int i, int j, int b, int n) { rs[i] |= (1 << n), cs[j] |= (1 << n), bs[b] |= (1 << n); } void reset(int i, int j, int b, int n) { rs[i] ^= (1 << n), cs[j] ^= (1 << n), bs[...