Question

Program in Java. There is an array of [0,1, ..., numCaves-1] with a policeman and a bad guy. The bad guy may appears in the any position of this array, he will changes his position each day, but can only move left or right by one cell. If the policeman and the bad guy are in the same cell, the bad guy is said to be caught. Given any initial position of the bad guy, the objective is output the policeman’s strategy that can guarantee to catch the bad guy, and demo the whole process (preferbaly with a GUI).

Neither knows what position the other is at. The bad guy must move left or right, while the policeman can move left and right as well as wait in a spot.

Answer 1

as GUI isn't mandatory i made it for cli..please comment if you need any gui version

for following o/p:

code:

import java.util.Random;

class PoliceBad{

char cavearray[];
int policepos;
int badguypos;
int turn;
PoliceBad(int numCaves)
{
this.cavearray=new char[numCaves];
int min=0;int max=numCaves-1;
for(int i=0;i<max;i++)
this.cavearray[i]=' ';
this.policepos=new Random(System.currentTimeMillis()).nextInt((max - min) + 1) + min;
this.badguypos=new Random(System.currentTimeMillis()+1000).nextInt((max - min) + 1) + min;
this.cavearray[this.badguypos]='b';
this.cavearray[this.policepos]='p';
this.turn=0;
}
void badMove()
{
int bpre=this.badguypos;
if(this.badguypos!=this.policepos)
{
if(this.badguypos==0)
this.badguypos=1;
else if(this.badguypos==this.cavearray.length-1)
this.badguypos=this.cavearray.length-2;
else{
int min=-1;int max=1;
int tmp=0;
while(tmp==0)
tmp=new Random(System.currentTimeMillis()).nextInt((max - min) + 1) + min; //-1 is left, 1 is right we loop until we won't get 0
this.badguypos=this.badguypos+tmp;
}
}
  
this.cavearray[bpre]=' ';
this.cavearray[this.badguypos]='b';
  
}

boolean catchBad()
{
if(this.policepos==this.badguypos)
{
return false;
}
return true;
}
void policeMove()
{
int ppre=this.policepos;
if(this.badguypos!=this.policepos)
{
if(this.policepos==0)
{int min=0;int max=1;
int tmp=new Random(System.currentTimeMillis()).nextInt((max - min) + 1) + min;
this.policepos+=tmp;}
else if(this.policepos==this.cavearray.length-1)
{int min=-1;int max=0;
int tmp=new Random(System.currentTimeMillis()).nextInt((max - min) + 1) + min;
this.policepos+=tmp;}
else{
int min=-1;int max=1;
int tmp=new Random(System.currentTimeMillis()).nextInt((max - min) + 1) + min; //-1 is left,0 is idle,1 is right
this.policepos+=tmp;
}
}
  
this.cavearray[ppre]=' ';
this.cavearray[this.policepos]='p';

  
}
public static void main(String[] args) {
int numCaves=5;
PoliceBad p=new PoliceBad(numCaves);
boolean flag=true;
while(flag)
{
System.out.print(" | ");
for(int i=0;i<p.cavearray.length;i++)
System.out.print(p.cavearray[i]+" | ");
System.out.println();
flag=p.catchBad();
p.badMove();
p.policeMove();
p.turn++;
}
System.out.println("police caught bad guy at turn: "+p.turn+" and pos: "+p.badguypos);

  
}
}