URAL1101[Robot in the Field]

CODE:

/*
PROGRAM: $PROGRAM
AUTHOR: Su Jiao
DATE: 2011-11-17
DESCRIPTION:
$DESCRIPTION
*/

import java.io.*;
import java.util.*;

public class Ural {
    public static void main(String args[])
    {
        new Ural();
    }
    public String exp;
    public int N,M,K;
    public int mx[],my[],kx[],ky[],iv[];
    public boolean vars[];
    public final int DIRS=4;
    public int dir,x,y;
    public int dx[],dy[];
    public int getid(char ch)
    {
        return (int)(ch-'A');
    }
    public boolean calc()
    {
        Stack<Boolean> va=new Stack<Boolean>();
        Stack<Character> op=new Stack<Character>();
        for (int i=0;i<exp.length();i++)
        {
            boolean opn1,opn2;
            switch (exp.charAt(i))
            {
                case '!':
                    op.push('!');
                    break;
                case '&':
                    while (!op.empty())
                    {
                        if (op.peek()=='!')
                        {
                            opn1=va.pop();
                            va.push(!opn1);
                        }
                        else if (op.peek()=='&')
                        {
                            opn1=va.pop();
                            opn2=va.pop();
                            va.push(opn1&&opn2);
                        }
                        else break;
                        op.pop();
                    }
                    op.push('&');
                    break;
                case '|':
                    while (!op.empty())
                    {
                        if (op.peek()=='!')
                        {
                            opn1=va.pop();
                            va.push(!opn1);
                        }
                        else if (op.peek()=='&')
                        {
                            opn1=va.pop();
                            opn2=va.pop();
                            va.push(opn1&&opn2);
                        }
                        else if (op.peek()=='|')
                        {
                            opn1=va.pop();
                            opn2=va.pop();
                            va.push(opn1||opn2);
                        }
                        else break;
                        op.pop();
                    }
                    op.push('|');
                    break;
                case '(':
                    op.push('(');
                    break;
                case ')':
                    while (op.peek()!='(')
                    {
                        if (op.peek()=='!')
                        {
                            opn1=va.pop();
                            va.push(!opn1);
                        }
                        else if (op.peek()=='&')
                        {
                            opn1=va.pop();
                            opn2=va.pop();
                            va.push(opn1&&opn2);
                        }
                        else if (op.peek()=='|')
                        {
                            opn1=va.pop();
                            opn2=va.pop();
                            va.push(opn1||opn2);
                        }
                        else break;
                        op.pop();
                    }
                    op.pop();
                    break;
                case '0':
                    va.push(false);
                    break;
                case '1':
                    va.push(true);
                    break;
                default:
                    va.push(vars[getid(exp.charAt(i))]);
                    break;
            }
        }
        return va.pop();
    }
    public Ural()
    {
        Scanner cin=new Scanner(new BufferedInputStream(System.in));
        exp=cin.nextLine();
        N=cin.nextInt();
        M=cin.nextInt();
        K=cin.nextInt();
        mx=new int[M];
        my=new int[M];
        kx=new int[K];
        ky=new int[K];
        iv=new int[K];
        for (int i=0;i<M;i++)
        {
            mx[i]=cin.nextInt();
            my[i]=cin.nextInt();
        }
        for (int i=0;i<K;i++)
        {
            kx[i]=cin.nextInt();
            ky[i]=cin.nextInt();
            iv[i]=getid(cin.next().charAt(0));
        }
        exp=exp.replaceAll("NOT","!");
        exp=exp.replaceAll("AND","&");
        exp=exp.replaceAll("OR","|");
        exp=exp.replaceAll("TRUE","1");
        exp=exp.replaceAll("FALSE","0");
        exp=exp.replaceAll(" ","");
        exp="("+exp+")";
        vars=new boolean[26];
        Arrays.fill(vars,false);
        dir=0;
        x=0;
        y=0;
        dx=new int[]{1,0,-1,0};
        dy=new int[]{0,1,0,-1};
        while (Math.abs(x)<=N&&Math.abs(y)<=N)
        {
            System.out.println(x+" "+y);
            for (int i=0;i<M;i++)
                if (mx[i]==x&&my[i]==y)
                {
                    if (calc())
                    {
                        if (dir==0) dir+=DIRS;
                        dir--;
                    }
                    else
                    {
                        dir++;
                        if (dir==DIRS) dir-=DIRS;
                    }
                }
            for (int i=0;i<K;i++)
                if (kx[i]==x&&ky[i]==y)
                    vars[iv[i]]=!vars[iv[i]];
            x+=dx[dir];
            y+=dy[dir];
        }
    }
}