Ada and Queue

最新推荐文章于 2025-06-03 13:28:20 发布

原创最新推荐文章于 2025-06-03 13:28:20 发布 · 362 阅读

0 ·

CC 4.0 BY-SA版权

---------ACM--------- 同时被 2 个专栏收录

10 篇文章

订阅专栏

模拟

2 篇文章

订阅专栏

本文介绍了一个关于Ada the Ladybug的编程挑战，她使用队列来管理任务，并且能够从队列的前后两端取出任务、反转队列以及将任务加入到队列的不同位置。文章通过一个具体的例子展示了如何使用双端队列(deque)来解决这个问题。

Ada and Queue

Ada the Ladybug has many things to do. She puts them into her queue. Anyway she is very indecisive, so sometime she uses the top, sometime the back and sometime she decides to reverses it.

Input

The first line consists of 1 ≤ Q ≤ 10⁶, number of queries. Each of them contains one of following commands

back - Print number from back and then erase it

front - Print number from front and then erase it

reverse - Reverses all elements in queue

push_back N - Add element N to back

toFront N - Put element N to front

All numbers will be 0 ≤ N ≤ 100

Output

For each back/front query print appropriate number.

If you would get this type of query and the queue would be empty, print "No job for Ada?" instead.

Example Input

15
toFront 93
front
back
reverse
back
reverse
toFront 80
push_back 53
push_back 50
front
front
reverse
push_back 66
reverse
front

Example Output

93
No job for Ada?
No job for Ada?
80
53
66

【分析】用deque模拟。

反转后，输入也要反转。

#include <iostream>
#include <cstdio>
#include <stack>
#include <cstring>
using namespace std;
const int maxn = 1e4 + 10;
typedef long long LL;
#define cl(a,b) memset(a,b,sizeof a);
int main()
{
    int n;
    while(~scanf("%d",&n)){
        deque<int> q;
        char s[100];
        int x;
        int flag=1;
        while(n--){
            scanf("%s",s);
            if(s[0] == 'b'){
                if(q.empty())
                    puts("No job for Ada?");
                else{
                    if(flag){
                        printf("%d\n",q.back());
                        q.pop_back();
                    }
                    else{
                        printf("%d\n",q.front());
                        q.pop_front();
                    }
                }
            }
            else
            if(s[0] == 'f'){
                if(q.empty())
                    puts("No job for Ada?");
                else{
                    if(!flag){
                        printf("%d\n",q.back());
                        q.pop_back();
                    }
                    else{
                        printf("%d\n",q.front());
                        q.pop_front();
                    }
                }
            }
            else
            if(s[0] == 'r'){
                flag = 1-flag;
            }
            else
            if(s[0] == 'p'){
                scanf("%d",&x);
                if(flag)
                    q.push_back(x);
                else
                    q.push_front(x);
            }
            else
            if(s[0] == 't'){
                scanf("%d",&x);
                if(flag)
                    q.push_front(x);
                else
                    q.push_back(x);
            }
        }
    }
    return 0;
}