P2802 回家（BFS）

import java.util.ArrayDeque;
import java.util.Scanner;
/**
 * BFS
 * 关键：三位数组标记走过的点，3滴血和5滴血走过的点是不一样的
 */
public class P2802 {
	static int T, n, m, ans;
	static int[][] map;
	static boolean[][][] flag;
	static int[][] dir = { { -1, 0 }, { +1, 0 }, { 0, -1 }, { 0, +1 } };

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		n = sc.nextInt();
		m = sc.nextInt();
		map = new int[n][m];
		flag = new boolean[n][m][7];
		NodeB start = null, end = null;
		for (int i = 0; i < n; i++) {
			for (int j = 0; j < m; j++) {
				map[i][j] = sc.nextInt();
				if (map[i][j] == 2) {
					start = new NodeB(i, j, 0, 6);
				}
				if (map[i][j] == 3) {
					end = new NodeB(i, j, 0, 0);
				}
			}
		}
		bfs(start, end);
		System.out.println(ans);

	}

	private static void bfs(NodeB start, NodeB end) {
		ArrayDeque<NodeB> que = new ArrayDeque<NodeB>();
		que.add(start);
		flag[start.x][start.y][start.p] = true;

		while (!que.isEmpty()) {
			NodeB node = que.getFirst();
			que.removeFirst();

			for (int i = 0; i < 4; i++) {
				NodeB dirNode = new NodeB(node.x + dir[i][0], node.y + dir[i][1], node.time + 1, node.p - 1);
				if (isVal(dirNode)) {
					if (map[dirNode.x][dirNode.y] == 4) {
						dirNode.p = 6;
					}
					if (dirNode.equals(end) && dirNode.p > 0) {
						ans = dirNode.time;
						return;
					}
					que.addLast(dirNode);
					flag[dirNode.x][dirNode.y][dirNode.p] = true;
				}
			}
		}
		ans = -1;
		return;
	}

	private static boolean isVal(NodeB dirNode) {
		int x = dirNode.x;
		int y = dirNode.y;
		int p = dirNode.p;
		return x >= 0 && x < n && y >= 0 && y < m && map[x][y] != 0 && flag[x][y][p] == false && p > 0;
	}
}

class NodeB {
	int x, y, time, p;

	public NodeB(int x, int y, int time, int p) {
		super();
		this.x = x;
		this.y = y;
		this.time = time;
		this.p = p;
	}

	@Override
	public int hashCode() {
		final int prime = 31;
		int result = 1;
		result = prime * result + x;
		result = prime * result + y;
		return result;
	}

	@Override
	public boolean equals(Object obj) {
		if (this == obj)
			return true;
		if (obj == null)
			return false;
		if (getClass() != obj.getClass())
			return false;
		NodeB other = (NodeB) obj;
		if (x != other.x)
			return false;
		if (y != other.y)
			return false;
		return true;
	}

}