再多组数据情况下，bfs忘记清空队列了！！！

题目来源: Dungeon Master

#include <iostream>
#include <queue>
#include <cstring>

using namespace std;

const int N = 35;

char g[N][N][N];

int n, m, k;

int sx, sy, sz, ex, ey, ez;

struct Node{
    int x, y, z;
};

queue<Node> q;
int dist[N][N][N];

int bfs()
{
    //清空队列
    queue<Node> tpq;
    q = tpq;
    memset(dist, 0x3f, sizeof dist);
    dist[sx][sy][sz] = 0;
    q.push(Node{sx, sy, sz});
    while(q.size())
    {
        Node t = q.front();
        q.pop();
        int dx[] = {0, 0, 1, -1, 0, 0}, dy[] = {0, 0, 0, 0, 1, -1}, dz[] = {1, -1, 0, 0, 0, 0};
        for(int i = 0; i < 6; ++ i)
        {
            int a = t.x + dx[i], b = t.y + dy[i], c = t.z + dz[i];
            if(a < 0 || a >= n || b < 0 || b >= m || c < 0 || c >= k)   continue;
            if(g[a][b][c] == '#')   continue;
            if(dist[a][b][c] != 0x3f3f3f3f) continue; //访问过
            dist[a][b][c] = dist[t.x][t.y][t.z] + 1;
            if(a == ex && b == ey && c == ez)
            {
                return dist[a][b][c]; //队列没清空
            }
            q.push(Node{a, b, c});
        }
    }
    return -1;
}

int main()
{
    while(cin >> n >> m >> k && (n && m && k))
    {
        for(int i = 0; i < n; ++ i)
            for(int j = 0; j < m; ++ j)
            {
                cin >> g[i][j];
                for(int t = 0; t < k; ++ t)
                {
                    if(g[i][j][t] == 'S')
                    {
                        sx = i, sy = j, sz = t;
                    }
                    else if(g[i][j][t] == 'E')
                    {
                        ex = i, ey = j, ez = t;
                    }
                }
            }
        int t = bfs();
        if(t == -1)
        {
            cout << "Trapped!" << endl;
        }
        else
        {
            cout << "Escaped in " << t << " minute(s)." << endl;
        }
    }
    return 0;
}