HDU 1702 ACboy needs your help again!
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
4 FIFO
IN 1
IN 2
OUT
OUT
4 FILO
IN 1
IN 2
OUT
OUT
5 FIFO
IN 1
IN 2
OUT
OUT
OUT
5 FILO
IN 1
IN 2
OUT
IN 3
OUT
Sample Output
1
2
2
1
1
2
None
2
3
题目大意：
输入a，表示a组测试数据，输入b和s表示接下来有b行命令，s表示是栈还是队列，s为FIFO表示队列，s为FILO为栈，命令为IN表示后面跟的数字进栈（队），OUT表示出栈顶（队首）元素出栈（队），当栈（队）为空时，执行OUT输出None。
C++
#include<iostream>
#include<cstdio>
#include<cstring>
#include<stack>
#include<queue>
using namespace std;
int main()
{
int a,b,c,d,e;
string s,n;
cin>>a;
while(a--)
{
cin>>b>>s;
if(s=="FIFO")
{
queue<int>m;
while(b--)
{
cin>>n;
if(n=="IN")
{
cin>>d;
m.push(d);
}
else
{
if(m.empty())
cout<<"None"<<endl;
else
{
d=m.front();
m.pop();
cout<<d<<endl;
}
}
}
}
else if(s=="FILO")
{
stack<int>m;
while(b--)
{
cin>>n;
if(n=="IN")
{
cin>>d;
m.push(d);
}
else
{
if(m.empty())
cout<<"None"<<endl;
else
{
d=m.top();
m.pop();
cout<<d<<endl;
}
}
}
}
}
return 0;
}
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