走迷宫-bfs

 

package Test;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {
    static int N = 110,hh = 0,tt = -1,n,m;
    static int[][] g = new int[N][N];   //用来存储迷宫
    static int[][] d = new int[N][N];   //用来存储d[i][j]到远点的距离
    static PII[] q = new PII[N * N];
    static int[] dx = {-1,0,1,0};
    static int[] dy = {0,1,0,-1};
    static BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
    public static int bfs(){
        d[0][0] = 0;    //初始化头节点距离为0
        //bfs模板
        //先把头节点放入队列中
        q[++tt] = new PII(0,0);
        //扩展放入队列的点
        while (hh<=tt){
            PII t = q[hh++];    //把头节点拿出来,然后再把头节点周围满足条件的点放入
            for (int i = 0; i < 4; i++) {
                int x = t.first + dx[i];    //行
                int y = t.second + dy[i];   //列
                if (x >= 0 && y >= 0 && x < n && y < m && g[x][y] == 0 && d[x][y] == -1){
                    d[x][y] = d[t.first][t.second] + 1;
                    //把扩展的点加入队列
                    q[++tt] = new PII(x,y);
                }
            }
        }
        //下标从0开始
        return d[n - 1][m - 1];
    }

    public static void main(String[] args) throws IOException {
        String[] init = in.readLine().split(" ");
        n = Integer.parseInt(init[0]);
        m = Integer.parseInt(init[1]);
        for (int i = 0; i < n; i++) {
            init = in.readLine().split(" ");
            for (int j = 0; j < m; j++) {
                g[i][j] = Integer.parseInt(init[j]);
                d[i][j] = -1;
            }
        }
        System.out.println(bfs());
        in.close();
    }
}
class  PII{
    int first;
    int second;

    public PII(int first, int second) {
        this.first = first;
        this.second = second;
    }
}