火车进站，模拟一个栈的操作，额外的栈操作，查看能否依照规定顺序出栈。

数据量非常少，故此题目非常easyAC。

直接使用数组模拟就好。

#include <stdio.h>

const int MAX_N = 10;

char inOrder[MAX_N], outOrder[MAX_N], stk[MAX_N];

bool rs[MAX_N<<2];

int n;

int main()

{

	while (scanf("%d", &n) != EOF)

	{

		scanf("%s %s", inOrder, outOrder);

		int j = 0, out = 0, i = 0, st = 0;

		bool possible = true;

		while (possible && !(st == 0 && out == n))

		{

			for (; i < n && inOrder[i] != outOrder[out]; i++)

			{

				rs[j++] = true;

				stk[st++] = inOrder[i];

			}//push in

			i++;//Watch out: don't forget while inOrder[i]==outOrder[out]!

			rs[j++] = true;

			rs[j++] = false;

			out++;

			while (st > 0 && stk[st-1] == outOrder[out])

			{

				st--; out++;

				rs[j++] = false;

			}//pop back

			int k = 0;//check possible

			for (; k < st && stk[k] != outOrder[out]; k++);

			if (k < st) possible = false;

		}

		if (possible)

		{

			puts("Yes.");

			for (int i = 0; i < j; i++)

			{

				if (rs[i]) puts("in");

				else puts("out");

			}

		}

		else puts("No.");

		puts("FINISH");

	}

	return 0;

}

解法二：

#include <stdio.h>

const int MAX_N = 10;

char inOrder[MAX_N], outOrder[MAX_N], stk[MAX_N];

bool rs[MAX_N<<2];

int n;

int main()

{

	while (scanf("%d", &n) != EOF)

	{

		scanf("%s %s", inOrder, outOrder);

		int j = 0, out = 0, i = 0, st = 0;

		while (i<n && !(st == 0 && out == n))

		{

			for (; i < n && inOrder[i] != outOrder[out]; i++)

			{

				rs[j++] = true;

				stk[st++] = inOrder[i];

			}//push in

			i++;//Watch out: don't forget while inOrder[i]==outOrder[out]!

			rs[j++] = true;

			rs[j++] = false;

			out++;

			while (st > 0 && stk[st-1] == outOrder[out])

			{

				st--; out++;

				rs[j++] = false;

			}//pop back

		}

		if (st == 0 && out == n)

		{

			puts("Yes.");

			for (int i = 0; i < j; i++)

			{

				if (rs[i]) puts("in");

				else puts("out");

			}

		}

		else puts("No.");

		puts("FINISH");

	}

	return 0;

}