李立链表

Description

一个初始化为空的队列,共有三种操作,pop,push,query

Input

pop操作, 输入pop, 输出并且删除队首的元素,如果没有则输出 empty!;

push操作,输入push d(d为一个整数);

query操作,输入query k(k为一个整数),输出队列中第k个元素,如果没有则输出 empty!.

Output

按要求输出

Sample Input

pop push 1 pop push 10 query 1

Sample Output

empty!

1

10

 

 

#include<stdio.h>
#include<string.h>
int queue[10000], front = 0, rear = 0;
void pop ( void )
{
     if ( front == rear )
     {
          printf ( "empty!\n" );
          return ;
     }
     printf ( "%d\n", queue[front++] );
}
void query ( void )
{
     int n;
     scanf ( "%d", &n );
     if ( n + front > rear )
     {
          printf  ( "empty!\n" );
          return ;
     }
     printf ( "%d\n", queue[front + n-1] );
}
void push()
{
    int n;
    scanf( "%d", &n );
    queue[rear] = n;
    rear++;
}
int main ( )
{
    char str[10];
    while ( scanf ( "%s", str ) == 1 )
    {
          if ( !strcmp ( "pop", str ) )
             pop ( );
          if ( !strcmp ( "query", str ) )
             query ( );
          if ( !strcmp ( "push", str ) )
             push ( );
    }
    return 0;
}