Dungeon Master (简单BFS)

Posted 2021-03-14 whitabbit

Problem Description

You are trapped in a 3D dungeon and need to find the quickest way out! The dungeon is composed of unit cubes which may or may not be filled with rock. It takes one minute to move one unit north, south, east, west, up or down. You cannot move diagonally and the maze is surrounded by solid rock on all sides.

Is an escape possible? If yes, how long will it take?

Input

The input consists of a number of dungeons. Each dungeon description starts with a line containing three integers L, R and C (all limited to 30 in size).
L is the number of levels making up the dungeon.
R and C are the number of rows and columns making up the plan of each level.
Then there will follow L blocks of R lines each containing C characters. Each character describes one cell of the dungeon. A cell full of rock is indicated by a ‘#‘ and empty cells are represented by a ‘.‘. Your starting position is indicated by ‘S‘ and the exit by the letter ‘E‘. There‘s a single blank line after each level. Input is terminated by three zeroes for L, R and C.

Output

Each maze generates one line of output. If it is possible to reach the exit, print a line of the form

Escaped in x minute(s).

where x is replaced by the shortest time it takes to escape.
If it is not possible to escape, print the line

Trapped!

Sample Input

3 4 5
S....
.###.
.##..
###.#

#####
#####
##.##
##...

#####
#####
#.###
####E

1 3 3
S##
#E#
###

0 0 0

Sample Output

Escaped in 11 minute(s).
Trapped!

简单的三维BFS,在普通的二维平面图上增加了层数这个维度,除了在同一层东南西北方向上行走之外,还可以在相邻层之间行走,例如:可以从(x,y,0)---->(x,y,1),读懂题意后就很好写了,BFS模板走起

#include <algorithm>
#include <bitset>
//#include <bits/extc++.h>
#include <cstring>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>

using namespace std;
//using namespace __gnu_pbds

#define ll long long
#define maxn 105

char maps[35][35][35];
int dir[6][3] = {{1, 0, 0}, {-1, 0, 0}, {0, 1, 0}, {0, -1, 0}, {0, 0, 1}, {0, 0, -1}}, step[35][35][35];
bool vis[35][35][35];
int L, R, C;

struct Node
{
    int l, r, c;
} start, end1;

bool check(Node x)
{
    if (x.l < 0 || x.l >= L || x.r < 0 || x.r >= R || x.c < 0 || x.c >= C || !vis[x.l][x.r][x.c] || maps[x.l][x.r][x.c] == ‘#‘)
    {
        return false;
    }
    return true;
}

void bfs()
{
    queue<Node> q;
    q.push(start);
    step[start.l][start.r][start.c] = 0;
    vis[start.l][start.r][start.c] = false;
    while (!q.empty())
    {
        Node now = q.front();
        q.pop();
        for (int i = 0; i < 6; ++i)
        {
            Node next = now;
            next.l += dir[i][0];
            next.r += dir[i][1];
            next.c += dir[i][2];
            // cout << next.l << "   " << next.r << "   " << next.c << endl;
            // cout << maps[next.l][next.r][next.c] << endl;
            if (check(next))
            {
                //cout << next.l << "   " << next.r << "   " << next.c << endl;
                step[next.l][next.r][next.c] = step[now.l][now.r][now.c] + 1;
                vis[next.l][next.r][next.c] = false;
                q.push(next);
            }
        }
    }
}

int main()
{
    while (scanf("%d%d%d", &L, &R, &C) && L && R && C)
    {
        memset(step, -1, sizeof(step));
        memset(vis, true, sizeof(vis));
        for (int i = 0; i < L; ++i)
        {
            for (int j = 0; j < R; ++j)
            {
                for (int k = 0; k < C; ++k)
                {
                    scanf(" %c", &maps[i][j][k]);
                    if (maps[i][j][k] == ‘S‘)
                    {
                        start.l = i;
                        start.r = j;
                        start.c = k;
                    }
                    else if (maps[i][j][k] == ‘E‘)
                    {
                        end1.l = i;
                        end1.r = j;
                        end1.c = k;
                    }
                }
            }
        }
        bfs();
        if (step[end1.l][end1.r][end1.c] != -1)
        {
            printf("Escaped in %d minute(s).
", step[end1.l][end1.r][end1.c]);
        }
        else
        {
            puts("Trapped!");
        }
    }
    return 0;
}