HDU(1702)：ACboy needs your help again!

ACM竞赛之FIFO与FILO问题解析

最新推荐文章于 2022-02-25 20:51:34 发布

Zayn123

最新推荐文章于 2022-02-25 20:51:34 发布

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本文详细解析了一道ACM竞赛题目，该题涉及FIFO（先进先出）和FILO（先进后出）的概念，通过实例演示了如何使用队列和栈解决相关问题。文章提供了完整的代码实现，帮助读者理解和掌握数据结构的应用。

题目：

Time Limit: 1000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 11822 Accepted Submission(s): 5917

Problem Description

ACboy was kidnapped!!
he miss his mother very much and is very scare now.You can't image how dark the room he was put into is, so poor :(.
As a smart ACMer, you want to get ACboy out of the monster's labyrinth.But when you arrive at the gate of the maze, the monste say :" I have heard that you are very clever, but if can't solve my problems, you will die with ACboy."
The problems of the monster is shown on the wall:
Each problem's first line is a integer N(the number of commands), and a word "FIFO" or "FILO".(you are very happy because you know "FIFO" stands for "First In First Out", and "FILO" means "First In Last Out").
and the following N lines, each line is "IN M" or "OUT", (M represent a integer).
and the answer of a problem is a passowrd of a door, so if you want to rescue ACboy, answer the problem carefully!

Input

The input contains multiple test cases.
The first line has one integer,represent the number oftest cases.
And the input of each subproblem are described above.

Output

For each command "OUT", you should output a integer depend on the word is "FIFO" or "FILO", or a word "None" if you don't have any integer.

Sample Input

4 FIFO

IN 1

IN 2

OUT

4 FILO

IN 1

IN 2

OUT

5 FIFO

IN 1

IN 2

OUT

5 FILO

IN 1

IN 2

OUT

IN 3

OUT

Sample Output

None

Source ：2007省赛集训队练习赛（1）

题解：

本题从输入输出上看很复杂，但是理解了整个题意就很简单，从“a word "FIFO" or "FILO".(you know "FIFO" stands for "First In First Out", and "FILO" means "First In Last Out").”这一句就可以想到栈、和队列的基本思想：先进后出、先进后出，所以根据题意直接调用queue、stack并运用。

题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=1702

#include<iostream>
#include<cstdio>
#include<cstring>
#include<stack>
#include<queue>
using namespace std;
stack <int> s;
queue <int> q;
char input[5];
int main()
{
    int t;
    scanf("%d",&t);
    while(t--)
    {
        int n;
        scanf("%d",&n);
        scanf("%s",input);
        if(input[2]=='F')
        {
            while(n--)
            {
                scanf("%s",input);
                if(input[0]=='I')
                {
                    int m;
                    scanf("%d",&m);
                    q.push(m);
                }
                else
                {
                    if(q.empty())
                      printf("None\n");
                    else
                    {
                       printf("%d\n",q.front());
                        q.pop();
                    }
                }
            }
        }
        else if(input[2]=='L')
        {
            while(n--)
            {
                scanf("%s",input);
                if(input[0]=='I')
                {
                    int m;
                    scanf("%d",&m);
                    s.push(m);
                }
                else
                {
                    if(s.empty())
                       printf("None\n");
                    else
                    {
                        printf("%d\n",s.top());
                        s.pop();
                    }
                }
            }
        }
        while(!s.empty())
            s.pop();
        while(!q.empty())
            q.pop();

    }
    return 0;
}