STL list的練習

/*
沒啥好說的。list的練習
題目描述
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!
*/

#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <ctime>

#include <iostream>
#include <cmath>
#include <algorithm>
#include <numeric>
#include <list>
#include <utility>

#include <cstring>
#include <vector>
#include <queue>
#include <map>
#include <string>
#include <memory.h>
using namespace std;

#define inf 0x3f3f3f3f
#define MAXN 1000
#define clr(x,k) memset((x),(k),sizeof(x))
#define cpy(x,k) memcpy((x),(k),sizeof(x))
#define Base 10000

#define max(a,b) ((a)>(b)?(a):(b))
#define min(a,b) ((a)<(b)?(a):(b))

int main(){
   // freopen("1702.in","r",stdin);
    list<int> li;
    char s[100];
    int t,n,num;
    scanf("%d",&t);
    while(t--){
        scanf("%d %s",&n,s);
        li.clear();
            if(!strcmp("FIFO",s)){
                for(int zz = 0;zz < n;zz++){
                    scanf("%s",s);
                    if(s[0]=='I'){
                        scanf("%d",&num);
                        li.push_back(num);
                    }else{
                        if(li.empty()){
                            printf("None\n");
                        }
                        else{
                            printf("%d\n",li.front());
                            li.pop_front();
                        }
                    }
                }
            }else{
                for(int zz = 0;zz < n;zz++){
                    scanf("%s",s);
                    if(s[0]=='I'){
                        scanf("%d",&num);
                        li.push_back(num);
                    }else{
                        if(li.empty()){
                            printf("None\n");
                        }else{
                            printf("%d\n",li.back());
                            li.pop_back();
                        }
                    }
                }
            }
    }
    return 0;
}