（hdu）1022 Train Problem I 火车进站问题

题目链接：http://acm.split.hdu.edu.cn/showproblem.php?pid=1022

Problem Description
As the new term comes, the Ignatius Train Station is very busy nowadays. A lot of student want to get back to school by train(because the trains in the Ignatius Train Station is the fastest all over the world ^v^). But here comes a problem, there is only one railway where all the trains stop. So all the trains come in from one side and get out from the other side. For this problem, if train A gets into the railway first, and then train B gets into the railway before train A leaves, train A can't leave until train B leaves. The pictures below figure out the problem. Now the problem for you is, there are at most 9 trains in the station, all the trains has an ID(numbered from 1 to n), the trains get into the railway in an order O1, your task is to determine whether the trains can get out in an order O2.

Input
The input contains several test cases. Each test case consists of an integer, the number of trains, and two strings, the order of the trains come in:O1, and the order of the trains leave:O2. The input is terminated by the end of file. More details in the Sample Input.

Output
The output contains a string "No." if you can't exchange O2 to O1, or you should output a line contains "Yes.", and then output your way in exchanging the order(you should output "in" for a train getting into the railway, and "out" for a train getting out of the railway). Print a line contains "FINISH" after each test case. More details in the Sample Output.

Sample Input

Sample Output
Yes.
in
in
in
out
out
out
FINISH
No.
FINISH

Hint
Hint

For the first Sample Input, we let train  get in, then train  and train .
So now train  is at the top of the railway, so train  can leave first, then train  and train .
In the second Sample input, we should let train  leave first, so we have to let train  get in, then train  and train .
Now we can let train  leave.
But after that we can't let train 1 leave before train 2, because train 2 is at the top of the railway at the moment.
So we output "No.".

题意：给出火车在进站口的顺序，火车进站，出站遵循先进后出的规律问能实现出站顺序如给出的顺序吗？能输出步骤，不能输出No

方法：用数组v[i]表示进站的第i个火车是v[i],用vis[i]表示火车i是否进站

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <stack>
#include <math.h>
#include <queue>
#include <vector>
using namespace std;
#define N 30
#define ll long long
#define met(a,b) memset(a,b,sizeof(a));
vector<vector<int> >Q;
int vis[N],v[N];
char dis[][]= {"in","out"};
int ans[N];
int a[N],b[N];
int main()
{
    int n;
    char s[N],sub[N];
    while(scanf("%d %s %s",&n,s,sub)!=EOF)
    {
        int f=;met(v,);
        for(int i=; i<n; i++)
            a[i]=s[i]-'';
        for(int i=; i<n; i++)
            b[i]=sub[i]-'';
        int k=,l=;
        for(int i=; i<n; i++)
        {
            if(!v[b[i]])///如果没进站，则把这辆火车前的火车进站
            {
                for(int j=; j<n; j++)
                {
                    if(a[j]==b[i])
                    {
                        ans[l++]=;
                        ans[l++]=;
                        v[a[j]]=;
                         break;
                    }
                    if(!v[a[j]])
                    {
                        vis[k++]=a[j];
                        v[a[j]]=;
                        ans[l++]=;
                    }
                }
            }
            else  ///已进站
            {
                if(vis[--k]==b[i])///判断是否在最上面
                {
                    ans[l++]=;
                }
                else
                    f=;
            }

        }
        if(f)
            printf("No.\nFINISH\n");
        else
        {
            printf("Yes.\n");
            for(int i=;i<l;i++)
                puts(dis[ans[i]]);
            printf("FINISH\n");
        }
    }
    return ;
}