POJ 2251 Dungeon Master

题目链接：http://poj.org/problem?id=2251

解析：

简单的三维BFS问题。

代码：

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <algorithm>
#include <vector>
#include <queue>
#include <stack>
#include <set>
#include <map>
using namespace std;
#define Lowbit(x) ((x)&(-(x)))
#define ll long long
#define mp make_pair
#define ff first
#define ss second
#define pb push_back
#define mod 10000007
//#define LOCAL
#define MAXN 100010
#define INF 1e9
#define Max 100010

int tx[]={0,0,0,0,1,-1};
int ty[]={1,0,-1,0,0,0};
int tz[]={0,1,0,-1,0,0};

char str[35][35][35];
bool visit[35][35][35];

typedef struct node{
    int x,y,z;
    int cost;
}NODE;
int L,R,C;

bool check(int x,int y,int z){
    if(x<0||x>=L||y<0||y>=R||z<0||z>=C||visit[x][y][z]||str[x][y][z]!='.')
        return false;
    visit[x][y][z] = true;
    return true;
}

int main(){
    while(~scanf("%d%d%d", &L,&R,&C),L||R||C){
        int i,j,k;
        for(i=0; i<L; ++i){
            for(j=0; j<R; ++j){
                scanf("%s", str[i][j]);
            }
        }

        NODE now,tar;
        for(i=0; i<L; ++i){
            for(j=0; j<R; ++j){
                for(k=0; k<C; ++k){
                    if(str[i][j][k]=='S'){
                        now.x = i;
                        now.y = j;
                        now.z = k;
                        str[i][j][k]='.';
                    }
                    else if(str[i][j][k]=='E'){
                        tar.x = i;
                        tar.y = j;
                        tar.z = k;
                        str[i][j][k]='.';
                    }
                }
            }
        }

        //BFS
        memset(visit,false,sizeof(visit));
        queue<NODE> que;
        now.cost = 0;
        que.push(now);
        visit[now.x][now.y][now.z] = true;
        int ans = -1;

        while(que.size()){
            now = que.front();
            que.pop();
            if(now.x==tar.x&&now.y==tar.y&&now.z==tar.z){
                ans = now.cost;
                break;
            }
            for(i=0; i<6; ++i){
                NODE tmp;
                tmp.x = now.x+tx[i];
                tmp.y = now.y+ty[i];
                tmp.z = now.z+tz[i];
                tmp.cost = now.cost+1;
                if(check(tmp.x,tmp.y,tmp.z)){
                    que.push(tmp);
                }
            }
        }

        if(-1==ans)
            printf("Trapped!\n");
        else
            printf("Escaped in %d minute(s).\n", ans);
    }
    return 0;
}