USACO_2_4_The Tamworth Two

很简单的模拟题目，代码有注释

 

 

/**//*
ID: sdjllyh1
PROG: ttwo
LANG: JAVA
complete date: 2008/12/21
author: LiuYongHui From GuiZhou University Of China
more article: www.cnblogs.com/sdjls
*/

import java.io.*;
import java.util.*;

public class ttwo
{
    private static int fFacing = 0;//人的面向，0表示北，1表示东，2表示南，3表示西
    private static int cFacing = 0;//牛的面向，同上
    private static char[][] forestMap = new char[10][10];//森林地图
    private static int fX, fY, cX, cY;//人和牛的坐标
    private static int minutes = 0;//模拟运行的时间
    private static int answer;//输出的结果
    private static boolean[][][][][][] appeared = new boolean[10][10][4][10][10][4];//记录某种状态是否出现过，前3个参数分别是人的x坐标、y坐标、面向，而后3个参数是牛的

    public static void main(String[] args) throws IOException
    {
        init();
        run();
        output();
        System.exit(0);
    }

    private static void run()
    {
        //当人和牛没有遇见且此状态没有出现过
        while ((!meet()) && (stateNotAppeared()))
        {
            //模拟进入下一分钟
            enterNextMinute();
        }
        //如果他们见面了
        if (meet())
        {
            //输出所用时间
            answer = minutes;
        }
        else//否则没有见面
        {
            //输出0
            answer = 0;
        }
    }
    //进入下一分钟
    private static void enterNextMinute()
    {
        if (canMove(fX, fY, fFacing))
        {
            fMove();
        }
        else
        {
            fRotate();
        }

        if (canMove(cX, cY, cFacing))
        {
            cMove();
        }
        else
        {
            cRotate();
        }

        minutes++;
    }
    //根据坐标与面向判断能否前进
    private static boolean canMove(int x, int y, int facing)
    {
        boolean retCanMove = true;

        switch (facing)
        {
            case 0:
                if ((x == 0) || (forestMap[x - 1][y] == '*'))
                {
                    retCanMove = false;
                }
                break;
            case 1:
                if ((y == 9) || (forestMap[x][y + 1] == '*'))
                {
                    retCanMove = false;
                }
                break;
            case 2:
                if ((x == 9) || (forestMap[x + 1][y] == '*'))
                {
                    retCanMove = false;
                }
                break;
            case 3:
                if ((y == 0) || (forestMap[x][y - 1] == '*'))
                {
                    retCanMove = false;
                }
                break;
        }
        return retCanMove;
    }
    //人前进一步
    private static void fMove()
    {
        switch (fFacing)
        {
            case 0:
                fX--;
                break;
            case 1:
                fY++;
                break;
            case 2:
                fX++;
                break;
            case 3:
                fY--;
                break;
        }
    }
    //牛前进一步
    private static void cMove()
    {
        switch (cFacing)
        {
            case 0:
                cX--;
                break;
            case 1:
                cY++;
                break;
            case 2:
                cX++;
                break;
            case 3:
                cY--;
                break;
        }
    }
    //人旋转
    private static void fRotate()
    {
        fFacing = (fFacing + 1) % 4;
    }
    //牛旋转
    private static void cRotate()
    {
        cFacing = (cFacing + 1) % 4;
    }
    //判断是否相遇，相遇返回true
    private static boolean meet()
    {
        if ((fX == cX) && (fY == cY))
        {
            return true;
        }
        else
        {
            return false;
        }
    }
    //判断此状态是否出现过，没出现过返回true
    private static boolean stateNotAppeared()
    {
        if (appeared[fX][fY][fFacing][cX][cY][cFacing])
        {
            return false;
        }
        else
        {
            appeared[fX][fY][fFacing][cX][cY][cFacing] = true;
            return true;
        }
    }

    private static void init() throws IOException
    {
        BufferedReader f = new BufferedReader(new FileReader("ttwo.in"));
        for (int i = 0; i < 10; i++)
        {
            String str = f.readLine();
            for (int j = 0; j < 10; j++)
            {
                forestMap[i][j] = str.charAt(j);
                if (forestMap[i][j] == 'F')
                {
                    fX = i;
                    fY = j;
                }
                if (forestMap[i][j] == 'C')
                {
                    cX = i;
                    cY = j;
                }
            }
        }
        f.close();
    }

    private static void output() throws IOException
    {
        PrintWriter out = new PrintWriter(new BufferedWriter(new FileWriter("ttwo.out")));
        out.println(answer);
        out.close();
    }
}