黑书上的一个小题

#include"iostream"const int Max= 10;const int Choice = 5;char ans[Max];int total[Choice] = {0};void tra(){for(int i = 0 ; i < Max ; i ++){if(ans[i] == 'a')total[0]++;if(ans[i] == 'b')total[1]++;if(ans[i] == 'c')total[2]++;if(ans[i] == 'd')total[3]++;if(ans[i] == 'e')total[4]++;}}bool rule_a(){int i = 0;for( ; i < Max && ans[i] != 'b' ; i++);for(int j = 0 ; j < 5 ; j ++){if(i < Max && ans[0] == 'a' + j && i == j + 2 - 1){return true;}}return false;}bool rule_b(){for(int i = 1 ; i < 6 ; i++){if(ans[1] == ('a' - 1 + i) && ans[i] == ans[i + 1])return true;}return false;}bool rule_c(){if(ans[2] == 'a' && ans[0] == 'a')return true;if(ans[2] == 'b' && ans[1] == 'b')return true;if(ans[2] == 'c' && ans[3] == 'c')return true;if(ans[2] == 'd' && ans[6] == 'd')return true;if(ans[2] == 'e' && ans[5] == 'e')return true;return false;}bool rule_d(){if(ans[3] == 'a' && total[0] == 0)return true;if(ans[3] == 'b' && total[0] == 1)return true;if(ans[3] == 'c' && total[0] == 2)return true;if(ans[3] == 'd' && total[0] == 3)return true;if(ans[3] == 'e' && total[0] == 4)return true;return false;}bool rule_e(){for(int i = 0 ; i < 5 ; i ++){if(ans[4] == 'a' + i && ans[4] == ans[9 - i])return true;}return false;}bool rule_f(){bool flag = true;for(int i = 0 ; i < 4 ; i ++){if(total[0] == total[i + 1]){flag = false;if(ans[5] == 'a' + i)return true;}}if(ans[5] == 'e' && flag)return true;return false;}bool rule_g(){int e = abs((int)(ans[6] - ans[7]));for(int i = 0 ; i < 5 ; i++){if(ans[6] == 'a' + i && 4 - i == e)return true;}return false;}bool rule_h(){int s = total[0] + total[4];for(int i = 0 ; i < 5 ; i ++){if(ans[7] == 'a' + i && i + 2 == s)return true;}return false;}bool rule_i(){int s = total[1] + total[2] + total[3];if(ans[8] == 'a' && (s == 2 || s == 3 || s == 5 || s == 7))return true;if(ans[8] == 'b' && (s == 1 || s == 2 || s == 6))return true;if(ans[8] == 'c' && (s == 1 || s == 4 || s == 9))return true;if(ans[8] == 'd' && (s == 1 || s == 8))return true;if(ans[8] == 'e' && (s == 5 || s == 10))return true;return false;}bool check(){memset(total,0,sizeof(total));tra();if(rule_a() && rule_b() && rule_c() && rule_d() && rule_e() && rule_f() && rule_g() && rule_h() && rule_i()){return true;}return false;}bool dfs(int depth){if(depth == Max && check()){for(int i = 0; i < Max; i++)printf("%c ",ans[i]);putchar('\n');return true;}if(depth < Max){for(int i = 0 ; i < 5 ; i++){ans[depth] = 'a' + i;dfs(depth + 1);ans[depth] -= i;}}return false;}int main(void){dfs(0);return 0;}