day60_p1(Open the lock).java

// Kohinoor diamond is robbed by Hrithik, He kept the diamond in a suitcase, 
// the suitcase has a lock with 4 circular wheels, and each wheel consist of
// 0-9 digits in the order 0,1,2,3,4,5,6,7,8,9 only.
// You can rotate a wheel from 0 to 9 or 9 to 0.

// As the diamond is most valuable, the lock has some traps,
// if anybody try to unlock the suitcase and reached any one of the traps,
// the suitcase will be blasted. And you will be dead.

// Initially, the suitcase lock is set to 0000.
// and you will be given the unlock key, your task to find and print
// the minimum number of rotations required to unlock the suitcase.
// If it is not possible to unlock the suitcase without blasting, print -1.

// NOTE:
// In one rotation you can choose any one wheel and 
// rotate to its next or previous digit.


// Input Format:
// -------------
// Line-1: space separated strings, each string of length 4 and contains only digits [0-9]
// Line-2: A string, key to unlock.

// Output Format:
// --------------
// Print an integer, the minimum number of rotations required to unlock.


// Sample Input-1:
// ---------------
// 0302 0202 0203 2323 3003
// 0303 

// Sample Output-1:
// ----------------
// 8

// Explanation:
// ------------
// To unlock the suitcase the valid rotations are as follows:
// 0000 > 1000 > 1100 > 1200 > 1201 > 1202 > 1302 > 1303 > 0303.


// Sample Input-2:
// ---------------
// 6656 6676 6766 6566 5666 7666 6665 6667
// 6666 

// Sample Output-2:
// ----------------
// -1

// Explanation:
// ------------
// You can't unlock the suitcase.


import java.util.*;
class j{
    static String plusone(String s,int ind){
        char[] c=s.toCharArray();
        if(c[ind]=='9'){
            c[ind]='0';
        }
        else{
            c[ind]+=1;
        }
        return new String(c);
    }
    static String minusone(String s,int ind){
        char[] c=s.toCharArray();
        if(c[ind]=='0'){
            c[ind]='9';
        }
        else{
            c[ind]-=1;
        }
        return new String(c);
    }
    public static void main (String[] args) {
        Scanner sc=new Scanner(System.in);
        String[] dead=sc.nextLine().split(" ");
        String t=sc.nextLine();
        Queue<String> q=new LinkedList<>();
        Set<String> vis=new HashSet<>();
        for(String i:dead){
            vis.add(i);
        }
        if(vis.contains("0000")){
            System.out.println(-1);
            System.exit(0);
        }
        q.add("0000");
        vis.add("0000");
        int steps=1;
        while(!q.isEmpty()){
            int c=q.size();
            while(c>0){
                String str=q.poll();
                for(int i=0;i<4;i++){
                    String a=plusone(str,i);
                    String b=minusone(str,i);
                    if(a.equals(t) || b.equals(t)){
                        System.out.println(steps);
                        System.exit(0);
                    }
                    if(!vis.contains(a)){
                        vis.add(a);
                        q.add(a);
                    }
                    if(!vis.contains(b)){
                        vis.add(b);
                        q.add(b);
                    }
                }
                c--;
            }
            steps++;
        }
        System.out.println(-1);
    }
}