POJ 1753 Flip Game Java实现版

版权声明： https://blog.csdn.net/moon_sky1999/article/details/84941233

C++实现：https://blog.csdn.net/moon_sky1999/article/details/75127657

Java代码：

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

public class Main {

    static int dx[] = {1, -1, 0, 0};
    static int dy[] = {0, 0, 1, -1};
    static int a[][];
    static boolean vis[];

    public static int get_num() {
        int pos = 0;
        for (int i = 1; i <= 4; ++i) {
            for (int j = 1; j <= 4; ++j) {
                if (a[i][j] == 1) {
                    int c = (i - 1) * 4 + j;
                    pos = (pos | (1 << (c - 1)));
                }
            }
        }
        return pos;
    }

    public static void move_back(int pos) {
        for (int i = 1; i <= 4; ++i) {
            for (int j = 1; j <= 4; ++j) {
                int c = (i - 1) * 4 + j;
                if ((pos & (1 << (c - 1))) != 0) a[i][j] = 1;
                else a[i][j] = 0;
            }
        }
    }

    public static void flip(int i, int j) {
        a[i][j] = 1 - a[i][j];
        for (int k = 0; k < 4; ++k) {
            if (i + dx[k] >= 1 && i + dx[k] <= 4 && j + dy[k] >= 1 && j + dy[k] <= 4) {
                a[i + dx[k]][j + dy[k]] = 1 - a[i + dx[k]][j + dy[k]];
            }
        }
    }

    public static void main(String[] args) {
        a = new int[5][5];
        vis = new boolean[200000];
        for (int j = 0; j < vis.length - 1; ++j)
            vis[j] = false;
        Scanner cin = new Scanner(System.in);
        for (int i = 1; i <= 4; ++i) {
            String s = cin.nextLine();
            for (int j = 0; j < 4; ++j) {
                if (s.charAt(j) == 'w')
                    a[i][j + 1] = 1;
                else a[i][j + 1] = 0;
            }
        }
        int pos = get_num();
        vis[pos] = true;
        Queue<Integer> p = new LinkedList<Integer>(), q = new LinkedList<Integer>();
        ((LinkedList<Integer>) q).push(pos);
        int tot = 0;
        boolean ok = false;
        while (!q.isEmpty()) {
            int x = ((LinkedList<Integer>) q).getFirst();
            ((LinkedList<Integer>) q).pop();
            if (x == 0 || x == 65535) {
                ok = true;
                break;
            }
            move_back(x);
            for (int i = 1; i <= 4; ++i) {
                for (int j = 1; j <= 4; ++j) {
                    flip(i, j);
                    int e = get_num();
                    if (vis[e] == false) {
                        vis[e] = true;
                        ((LinkedList<Integer>) p).push(e);
                    }
                    flip(i, j);
                }
            }
            if(q.isEmpty()){
                ++tot;
                while(!p.isEmpty()){
                    ((LinkedList<Integer>) q).push(((LinkedList<Integer>) p).getFirst());
                    ((LinkedList<Integer>) p).pop();
                }
            }
        }
        if(ok==true)
            System.out.println(tot);
        else System.out.println("Impossible");
    }
}