HDU 1022 Train Problem I

HDU 1022 Train Problem I

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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.

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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.

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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.

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Sample Input

3 123 321
3 123 312
Sample Output

Yes.
in
in
in
out
out
out
FINISH
No.
FINISH
Hint

For the first Sample Input, we let train 1 get in, then train 2 and train 3.
So now train 3 is at the top of the railway, so train 3 can leave first, then train 2 and train 1.
In the second Sample input, we should let train 3 leave first, so we have to let train 1 get in, then train 2 and train 3.
Now we can let train 3 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.”.

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这道题就是简单的模拟栈，给你一个进栈的顺序，问你是不是能按指定顺序输出，如果能的话，就输入进栈和出栈的顺序

按给的进栈顺序，让他们一个个进栈，如果栈顶元素与将要出栈的元素相等，就让这个元素出栈，然后指针指向下一个元素。同时用一种数组记录此刻是进栈还是出栈，最后判断栈是不是空栈。如果是空栈的话，就满足条件，输出进栈和出栈的顺序。如果不是空栈，就不满足条件。

代码如下~

 #include<iostream>
 #include <cstdio>
 #include <string.h>
 #include <stack>
using namespace std;
int main()
{
 #ifndef ONLINE_JUDGE 
    freopen("1.txt", "r", stdin);
 #endif
    int n, len;
    bool flag[20];
    char in[15], out[15];
    while(~scanf("%d%s%s", &n, in,out))
    {
        stack s;
        int i = 0, j = 0, k = 0;
        for (i = 0; i < n; i++)
        {
            s.push(in[i]);
            flag[k++] = true;
            while(!s.empty() && s.top() == out[j])
            {
                j++;
                flag[k++] = false;
                s.pop();
            }

        }
        if (j == n)
        {
            cout << "Yes." << endl;
            for (i = 0; i < k; i++)
            {
                if (flag[i])
                {
                    cout << "in" << endl;
                }
                else
                {
                    cout << "out" << endl;
                }
            }
        }
        else 
        {
            cout << "No." << endl;
        }

        cout << "FINISH" << endl;
    }

    return 0;
}