牛客小白月赛13.G-小A与小B

https://ac.nowcoder.com/acm/contest/549/G
 

import java.util.LinkedList;
import java.util.Queue;
import java.util.Scanner;

public class Main {
	static int[] dx = new int[] { 0, 0, 1, -1, 1, -1, 1, -1 };
	static int[] dy = new int[] { -1, 1, 0, 0, 1, -1, -1, 1 };
	static Queue<int[]>[] q = new Queue[2];
	static int[][][] vis;
	static int[][] maze;
	static int N;
	static int M;

	@SuppressWarnings("resource")
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		N = scan.nextInt();
		M = scan.nextInt();
		maze = new int[N][M];
		vis = new int[2][N][M];
		q[0] = new LinkedList<>();
		q[1] = new LinkedList<>();
		int Ax = 0, Ay = 0, Bx = 0, By = 0;
		// make maze
		for (int i = 0; i < N; ++i) {
			for (int j = 0; j < M; ++j) {
				maze[i][j] = scan.next().charAt(0);
				if (maze[i][j] == 'C') {
					Ax = i;
					Ay = j;
				} else if (maze[i][j] == 'D') {
					Bx = i;
					By = j;
				}
			}
		}
		//
		int ans = solve(Ax, Ay, Bx, By);
		if (ans == -1)
			System.out.println("NO");
		else {
			System.out.println("YES");
			System.out.println(ans);
		}
	}

	private static int solve(int Ax, int Ay, int Bx, int By) {
		// TODO Auto-generated method stub
		// 两个队列分别初始化
		q[0].offer(new int[] { Ax, Ay });
		vis[0][Ax][Ay] = 1;
		q[1].offer(new int[] { Bx, By });
		vis[1][Bx][By] = 1;
		// 两个队列都空才停止
		int time = 0;
		while (!q[0].isEmpty() || !q[1].isEmpty()) {
			++time;
			if (bfs(0))
				return time;
			if (bfs(1))
				return time;
			if (bfs(1))
				return time;
		}
		return -1;
	}

	private static boolean bfs(int t) {
		// TODO Auto-generated method stub
		int size = q[t].size();
		while (size-- > 0) {
			int[] cur = q[t].poll();
			for (int i = 0; i < (t == 0 ? 8 : 4); ++i) {
				int x = cur[0] + dx[i];
				int y = cur[1] + dy[i];
				if (x < 0 || y < 0 || x >= N || y >= M || maze[x][y] == '#' || vis[t][x][y] == 1)
					continue;
				// ans
				if (vis[1 - t][x][y] == 1)
					return true;
				q[t].offer(new int[] { x, y });
				vis[t][x][y] = 1;
			}
		}
		return false;
	}
}