POJ 2251 题解

 1 #include "iostream"
 2 #include "cstdio"
 3 #include "fstream"
 4 #include "sstream"
 5 #include "cstring"
 6 
 7 using namespace std;
 8 const int maxN = 3e4 + 1e2 ;
 9 struct Queue { int x , y , z ; } ;
10 typedef long long QAQ ; 
11 
12 int dx[ ] = { 1 , -1 , 0 , 0 , 0 , 0 } ;
13 int dy[ ] = { 0 , 0 , 0 , 0 , -1 , 1 } ;
14 int dz[ ] = { 0 , 0 , -1 , 1 , 0 , 0 } ;
15 
16 int step[ maxN ] ;
17 Queue Q[ maxN ] ;
18 bool vis[ 40 ][ 40 ][ 40 ] ;
19 char map[ 40 ][ 40 ][ 40 ] ;
20 
21 int L , R , C ;
22 int start_x , start_y , start_z , des_x , des_y , des_z ;
23 //QAQ Ans ;
24 
25 void Init ( ) {
26         memset ( vis , false , sizeof ( vis ) ) ;
27     memset ( step , 0 , sizeof ( step ) ) ;
28 } 
29 
30 inline bool Check ( const int x_x , const int y_y , const int z_z ) {return ( x_x == des_x && y_y == des_y && z_z == des_z ) ? true : false ; }
31 int BFS ( ) {
32     int Head = 0 , Tail = 0 ;
33     Q[ Tail ].x = start_x ; 
34         Q[ Tail ].y = start_y ; 
35         Q[ Tail ].z = start_z ;
36     while ( Head <= Tail ) {
37         for ( int i=0 ; i<6 ; ++i ) {
38             int xx = Q[ Head ].x + dx[ i ] ;
39             int yy = Q[ Head ].y + dy[ i ] ;
40             int zz = Q[ Head ].z + dz[ i ] ;
41             if( !vis[ xx ][ yy ][ zz ] && ( map[ xx ][ yy ][ zz ] == ‘.‘  ) && xx >= 0 && xx < L && yy >= 0 && yy < R && zz >= 0 && zz < C ) {
42                 vis[ xx ][ yy ][ zz ] = true ;
43                 Q[ ++Tail ].x = xx ;
44                 Q[ Tail ].y = yy ;
45                 Q[ Tail ].z = zz ;
46                 step [ Tail ] = step[ Head ] + 1 ;
47                 if ( Check ( xx , yy , zz ) ) return step[ Tail ] ;
48             }
49         }
50         ++ Head ;
51     }
52     return false ;
53 }
54 
55 void Scan ( ) {
56         for ( int i=0 ; i<L ; ++i , getchar ( ) ){
57         for ( int j=0 ; j<R ; ++j , getchar ( ) ){
58                 for ( int k=0 ; k<C ; ++k ) {
59                 map[ i ][ j ][ k ] = getchar ( ) ;
60                 if ( map[ i ][ j ][ k ] == ‘S‘ ) {
61                     start_x = i ;
62                                         start_y = j ;
63                                         start_z = k ;
64                                 }
65                                 else if ( map[ i ][ j ][ k ] == ‘E‘ ) {
66                                         map[ i ][ j ][ k ] = ‘.‘ ; 
67                                         des_x = i ;
68                                         des_y = j ; 
69                                         des_z = k ; 
70                                 }
71             }
72                 }    
73         }
74 }
75 
76 inline void Print ( int temp ) {
77         if( temp ) printf ( "Escaped in %d minute(s).\n" , temp ) ;
78     else printf ( "Trapped!\n" ) ;
79 }
80 
81 int main ( ) {
82     while ( scanf ( "%d %d %d\n " , &L , &R , &C ) == 3 && L && R && C ) {
83             Init ( ) ;
84             Scan ( );
85             Print ( BFS( ) ) ;
86     }
87     return 0 ;
88 }