sicily 1022. Train Problem

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1022. Train Problem

Total:

2206

Accepted:

703

	Time Limit: 1sec    Memory Limit:256MB 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  Copy sample input to clipboard 3 123 321 3 123 312 Sample Output Yes. in in in out out out FINISH No. FINISH Problem Source: 2012年期末机考（Pan）

代码：

// Problem#: 8670
// Submission#: 2493920
// The source code is licensed under Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License
// URI: http://creativecommons.org/licenses/by-nc-sa/3.0/
// All Copyright reserved by Informatic Lab of Sun Yat-sen University
#include<iostream>
#include<stack>
#include<string>
#include<vector>
#include<stdio.h>
using namespace std;
int main() {
    string in_ = "in";
    string out_ = "out";
    string finish = "FINISH";   
    string in;
    string out;
    int trains;
    
    while (scanf("%d", &trains) != EOF) {
          cin >> in >> out;
          stack<char> station;
          vector<string> state;
          for (int i = 0; i < in.size(); i++) {
              if (in[i] == out[0]) {
                  state.push_back(in_);
                  state.push_back(out_);
                  out.erase(out.begin());
                  while (!station.empty()) {//关键一步
                       if (station.top() == out[0]) {
                           state.push_back(out_);
                           out.erase(out.begin());
                           station.pop();
                       } else
                          break;
                  }                
              } else {
                  station.push(in[i]);
                  state.push_back(in_);
              }
          }
          state.push_back(finish);
          if (station.empty()) {
              cout << "Yes." << endl;
              for (int i = 0; i < state.size(); i++)
                   cout << state[i] << endl;
          } else
              cout << "No." << endl << finish << endl;
     }
     return 0;
}