我是超级新手。。基本不会堆栈。。用数组为什么总是WA，试了好多次了，都是对的啊
#include <stdio.h>
#include <string.h>
int main()
{
	char arr[200][200]={"http://www.acm.org/"},command[10],a[4][10]={"VISIT","BACK","FORWARD","QUIT"};
	int i=1,n;
	while(1)
	{
		scanf("%s",command);
		if(strcmp(command,a[0])==0)
		{
			if(arr[i][1]!=0)
			{
				scanf("%s",arr[i]);
				printf("%s\n",arr[i]);
				i++;
			}
			else
			{
				n=i;
				for(;arr[i][1]!=0;i++);
				for(;i>n;i--)
					arr[i][101]=arr[i-1][101];
				scanf("%s",arr[n]);
				printf("%s\n",arr[i]);
				i++;
			}
		}
		else if(strcmp(command,a[1])==0)
		{
			if(i<=1)  printf("Ignored\n");
			else 
			{
				i=i-2;
				printf("%s\n",arr[i]);
				i=i+1;
			}
		}
		else if(strcmp(command,a[2])==0)
		{
			if(arr[i][1]==0) printf("Ignored\n");
			else 
			{
				printf("%s\n",arr[i]);
				i=i+1;
			}
		}
		else if(strcmp(command,a[3])==0) break;
	}
	return 0;
}