叕来贪空间了

可贪空间已不足500B(?)

#include <stdio.h>
short n,m,vis[41][41],sum,sx,sy,fx,fy,zhx,zhy,t;
short a[51][51],dx[]={1,-1,0,0};
short dy[]={0,0,1,-1};
void f(int x,int y){
	if(x==fx&&y==fy){
		sum++;
        return;
	}
	vis[x][y]=1;
	for(int i=0;i<4;i++){
		int nx=x+dx[i];
		int ny=y+dy[i];
		if(vis[nx][ny])continue;
		if(nx<1||nx>n||ny<1||ny>m){
			continue;
		}
		if(a[nx][ny]==1){
			continue;
		}
		f(nx,ny);
	}
    vis[x][y]=0;
	
}
int main(){
	scanf("%hd %hd %hd",&n,&m,&t);
    scanf("%hd %hd %hd %hd",&sx,&sy,&fx,&fy);
	for(int j=1;j<=t;j++){
		scanf("%hd %hd",&zhx,&zhy);
        a[zhx][zhy]=1;
	}
	f(sx,sy);
	printf("%hd",sum);
}