Hdu 1429 bfs + state Compression

Hdu 1429 bfs + state Compression
// Open a 3D tag array to mark whether Ignatius has reached the location in the key-getting state.
// Because the number of keys is up to 10, you can use state Compression
// Use 1 and 0 to indicate whether there are any I-th keys. In this way, the key State obtained by this person can be expressed in binary.
// Use bfs to find the minimum value
# Include
# Include
# Include
# Include
Using namespace std;
Const int maxn = 30;
Const int inf = 0x7fffffff;
Int vis [maxn] [maxn] [1 <10];
Char map [maxn] [maxn];
Int ans = ans;
Struct node
{
Int x, y;
Int step;
Int state;
};
Int st_x, st_y;
Int n, m;
Int dx [4] = {-1, 0, 1, 0 };
Int dy [4] = {0, 1, 0,-1 };
Queue Que;
Void bfs ()
{
While (que. size ())
Que. pop ();
Memset (vis, 0, sizeof (vis ));
Struct node first = {st_x, st_y, 0, 0 };
Vis [st_x] [st_y] [0] = 1;
Que. push (first );
While (que. size ())
{
Struct node now = que. front ();
Que. pop ();
If (map [now. x] [now. y] = '^ ')
{
Ans = now. step;
Break;
}
For (int I = 0; I <4; I ++)
{
Struct node next;
Next. x = now. x + dx [I];
Next. y = now. y + dy [I];
If (map [next. x] [next. y] = '*' | next. x <1 | next. x> n | next. y <1 | next. y> m)
Continue;
If (map [next. x] [next. y]> = 'A' & map [next. x] [next. y] <= 'J ')
If (! (Now. state & (1 <(map [next. x] [next. y]-'A '))))
Continue;
If (map [next. x] [next. y]> = 'A' & map [next. x] [next. y] <= 'J ')
{
Next. state = now. state | (1 <(map [next. x] [next. y]-'A '));
Next. step = now. step + 1;
If (vis [next. x] [next. y] [next. state])
Continue;
Que. push (next );
Vis [next. x] [next. y] [next. state] = 1;
Continue;
}
Next. state = now. state;
Next. step = now. step + 1;
If (vis [next. x] [next. y] [next. state])
Continue;
Vis [next. x] [next. y] [next. state] = 1;
Que. push (next );
}
}
}
Int main ()
{
// Freopen(in.txt, r, stdin );
Int time;
While (scanf (% d, & n, & m, & time )! = EOF)
{
For (int I = 1; I <= n; I ++)
{
Scanf (% s, & map [I] [1]);
For (int j = 1; j <= m; j ++)
If (map [I] [j] = '@')
St_x = I, st_y = j;
}
Ans = inf; // The end point may not be reached, so it is possible that the bfs does not update ans.
Bfs (); // so ans must initialize each time.
If (ans <time)
Printf (% d, ans );
Else
Printf (-1 );
}
Return 0;
}