P4554 小明的游戏

SPFA板子题

#include <stdio.h>
#include <string.h>
#define Clean(X,K) memset(X,K,sizeof(X))
#define re register
#define GC getchar()
#define Jud(X,Y) (X<0||X>=N||Y<0||Y>=M)
int Qread () {
	int X = 0 ;	char C = GC ;
	while (C > '9' || C < '0') C = GC ;
	while (C >='0' && C <='9') {
		X = X * 10 + C - '0' ;
		C = GC ;
	}
	return X ;
}
const int Maxn = 505 ,INF = 20021020 << 2 , U = 500 * 500 + 5;
int N , M , Mdis[Maxn][Maxn] , Vis[Maxn][Maxn] , Qx[Maxn * Maxn] , Qy[Maxn * Maxn] , Head , Tail ;
const short int Dx[] = {-1,1,0,0} , Dy[] = {0,0,-1,1} ;
char A[Maxn][Maxn] ;
int SPFA (int Sx , int Sy , int Ex , int Ey) {
	Clean (Mdis , 0x3f) , Clean(Vis , 0) , Head = Tail = 1 ;
	Mdis[Sx][Sy] = 0 , Vis[Sx][Sy] = 1 ;
	if (++ Tail > U) Tail = 0 ;
	Qx[Tail] = Sx , Qy[Tail] = Sy ;
	while (Head != Tail) {
		if (++ Head > U) Head = 0 ;
		int Nx = Qx[Head] , Ny = Qy[Head] ;
		Vis[Nx][Ny] = 0 ;
		for (re int i = 0 ; i < 4 ; ++ i) {
			int Tx = Nx + Dx[i] , Ty = Ny + Dy[i] ;
			if (Jud(Tx , Ty)) continue ;
			int Dis = Mdis[Nx][Ny] + (A[Tx][Ty] == A[Nx][Ny] ? 0 : 1) ;
			if (Dis < Mdis[Tx][Ty]) {
				Mdis[Tx][Ty] = Dis ;
				if (!Vis[Tx][Ty]) {
					Vis[Tx][Ty] = 1 ;
					if (++ Tail > U) Tail = 0 ;
					Qx[Tail] = Tx , Qy[Tail] = Ty ;
				}
			}
		}
	}
	return Mdis[Ex][Ey] ;
}
int main () {
//	freopen ("P4554.in" , "r" , stdin) ;
	N = Qread () , M = Qread () ;
	while (N + M) {
		for (re int i = 0 ; i < N; ++ i) for (re int j = 0 ; j < M; ++ j) {
				char C = GC ;
				while (C != '#' && C != '@') C = GC ;
				A[i][j] = C ;
			}
		int Sx = Qread () , Sy = Qread () , Ex = Qread () , Ey = Qread ();
		printf ("%d\n" , SPFA (Sx , Sy , Ex , Ey)) ;
		N = Qread () , M = Qread () ;
	}
	fclose (stdin) , fclose (stdout) ;
	return 0 ;
}