Online-coding-problems/red_knight.java at master · JaharshKotha/Online-coding-problems · GitHub

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import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {


    public static class pos
    {
        int x;
        int y;
        String c;
        pos(int x,int y,String c)
        {
            this.x = x;
            this.y =y;
            this.c = c;
        }
    }
    static boolean check(int i_start, int j_start, int i_end, int j_end,int r,int c)
    {
        if(r<i_start || c<j_start ||r>i_end||c>j_end)
            return true;
        else
            return false;
    }

    static ArrayList<pos> populate(int i_start,int j_start,int i_end,int j_end)
    {
        ArrayList<pos> tem = new ArrayList<pos>();
      if(check(i_start,j_start,i_end,j_end,i_start-2,j_start-1))
        {
            pos p = new pos(i_start-2,j_start-1,"UL");
           tem.add(p);
        }
        if(check(i_start,j_start,i_end,j_end,i_start-2,j_start+1))
        {
            pos p = new pos(i_start-2,j_start+1,"UR");
           tem.add(p);
        }
        if(check(i_start,j_start,i_end,j_end,i_start+2,j_start-1))
        {
            pos p = new pos(i_start+2,j_start+1,"LR");
           tem.add(p);
        }
        if(check(i_start,j_start,i_end,j_end,i_start+2,j_start+1))
        {
            pos p = new pos(i_start+2,j_start-1,"LL");
           tem.add(p);
        }
        if(check(i_start,j_start,i_end,j_end,i_start,j_start-2))
        {
            pos p = new pos(i_start,j_start-2,"L");
           tem.add(p);
        }
        if(check(i_start,j_start,i_end,j_end,i_start,j_start+2))
        {
            pos p = new pos(i_start,j_start+2,"R");
           tem.add(p);
        }

        return tem;
    }
    static boolean checkpathrepetition(ArrayList<pos> next , pos p)
    {
        for(int i=0;i<next.size();i++)
        {
            if(p.x == next.get(i).x && p.y == next.get(i).y)
                return false;
        }
        return true;
    }
    static void printShortestPath(int n, int i_start, int j_start, int i_end, int j_end) {
        //  Print the distance along with the sequence of moves.
        Queue<ArrayList<pos>> q = new LinkedList<ArrayList<pos>>();
        pos p = new pos(i_start,j_start,"S");
        ArrayList<pos> tem= new ArrayList<pos>();
        tem.add(p);
        ArrayList<ArrayList<pos>> result = new ArrayList<ArrayList<pos>>();
        q.add(tem);
        int min =10000,flg=0;
        int itr=0;
        while(!q.isEmpty())
        {
            if(itr>50)
                break;
            ArrayList<pos> path = q.remove();
            //System.out.println(path);
            pos cur = path.get(path.size()-1);
            ArrayList<pos> temp = populate(cur.x,cur.y,i_end,j_end);
            if(temp.size()==0)
                continue;

            for(int i=0;i<temp.size();i++)
        {
         ArrayList<pos> next = new ArrayList<pos>(path);
                if(!checkpathrepetition(next,temp.get(i)))
                    continue;

         next.add(temp.get(i));
          if(flg==1 && next.size()>min)
              continue;
         if(temp.get(i).x == i_end && temp.get(i).y==j_end)
         {
             if(min>next.size())
             {
                 flg=1;
                min =  next.size();
                result.add(next);
             }


         }
                else
                {
                 q.add(next);
                }

        }
            ++itr;
        }
        if(result.size()==0)
          System.out.println("Impossible");
        else
        {
            ArrayList<pos> prin = result.get(0);
            System.out.println(prin.size()-1);
            for(int i=1;i<prin.size();i++)
            {
                System.out.print(prin.get(i).c+" ");
            }
        }


    }


    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        int i_start = in.nextInt();
        int j_start = in.nextInt();
        int i_end = in.nextInt();
        int j_end = in.nextInt();
        printShortestPath(n, i_start, j_start, i_end, j_end);
        in.close();
    }
}