Pku 1028 Web Navigation

Pku 1028 Web Navigation

#include  < stdio.h >
#include  < string .h >

#define  N 110

char  str[ 10 ];
char  queue[N][ 100 ];
int   top =   0 ;
int   len =   1 ;

int  main()
{
    strcpy( queue[ ++ top],  " http://www.acm.org/ "  );
    
     while ( scanf( " %s " , str), strcmp( str,  " QUIT " ) !=   0  )
     {
         if ( strcmp( str,  " VISIT " ) ==   0  )
         {
            scanf( " %s " , queue[ ++ top] );
            printf( " %s\n " , queue[top] );
            
            len =  top;
        }
         else   if ( strcmp( str,  " BACK "  ) ==   0  )
         {
            top -- ;
             if ( top <   1  )
             {
                printf( " Ignored\n " );
                top ++ ;
            }
             else  printf( " %s\n " , queue[top] );
        }
         else   if ( strcmp( str,  " FORWARD "  ) ==   0  )
         {
            top ++ ;
            
             if ( top >  len )  {  printf( " Ignored\n " );  top -- ; }
             else   printf( " %s\n " , queue[top] );
        }
    }
    
     return   0 ;
}