poj 1363 Rails

#include<stdio.h>
#include<string.h>
int main()
{
int a[1010],b[1010],n,i,p,j,btop;
while(scanf("%d",&n),n)
{
memset(a,0,sizeof(a));
memset(b,0,sizeof(b));
while(1)
{
scanf("%d",&a[0]);
if(a[0]==0) break;
for(i=1;i<n;i++)
scanf("%d",&a[i]);
for(p=0,btop=i=1;i<=n;i++){
b[btop++]=i;
while(btop>1&&b[btop-1]==a[p])
{
btop--;
p++;
}
}//核心代码
if(p==n) printf("Yes\n");
else printf("No\n");
}
printf("\n");
}
return 0;
}