bulls and cows
import java.util.*;
class Main {
static ArrayList<String> possib = new ArrayList<String>();
public static void main(String args[]) {
System.out.println("COWS AND BULLS SOLVER:");
init();
Scanner in = new Scanner(System.in);
while (possib.size() > 1) {
String guess = possib.get((int)(Math.random() * possib.size()));
System.out.print(guess+" ");
int bulls = in.nextInt();
int cows = in.nextInt();
for (int j = 0; j < possib.size(); j++)
if (!check(possib.get(j),guess,cows,bulls)) {
possib.remove(j);
j--;
}
}
for (int j = 0; j < possib.size(); j++)
System.out.println(possib.get(j));
}
static void init() {
for (int a = 1; a <= 9; a++) {
for (int b = 1; b <= 9; b++) {
if (b == a) continue;
for (int c = 1; c <= 9; c++) {
if (c == b || c == a) continue;
for (int d = 1; d <= 9; d++) {
if (d == a || d == b || d == c) continue;
String cnt = ""+a+b+c+d;
possib.add(cnt);
}
}
}
}
}
static boolean check(String ans,String guess,int cows,int bulls) {
for (int i = 0; i < guess.length(); i++) {
int ind = ans.indexOf(guess.charAt(i));
if (ind == i) bulls--;
else if (ind >= 0) cows--;
}
return (cows == 0) && (bulls == 0);
}
}