CCF认证-201903-2 二十四点提示运行错误。。。求大佬解决

#include<iostream>

#include<stack>

using namespace std;

bool cmp(char top, char out)

{

	if ((top == '+' || top == '-') && (out == '+' || out == '-'))

		return true;

	else if ((top == 'x' || top == '/') && (out == 'x' || out == '/'))

		return true;

	else if ((top == 'x' || top == '/') && (out == '+' || out == '-'))

		return true;

	else

		return false;

}

int calculate(int nx, int nh, char sign)

{

	switch (sign)

	{

	case '+': return nx + nh;break;

	case '-': return nx - nh;break;

	case 'x': return nx * nh;break;

	case '/': return nx / nh;break;

	}

}

char s[8];

int main()

{

	int n;

	scanf("%d", &n);

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

	{

		stack<int> num;

		stack<char> sym;

		while (!num.empty())

			num.pop();

		while (!sym.empty())

			sym.pop();

		for (int j = 0; j < 8; j++)

		{

			scanf("%c", &s[j]);

			if (s[j] != '\n')

			{

				if (s[j] >= '0' && s[j] <= '9')

					num.push(s[j] - '0');

				else if (sym.empty())

				{

					sym.push(s[j]);

				}

				else

				{

					if (cmp(sym.top(), s[j]))

					{

						while (cmp(sym.top(), s[j]))

						{

							int nh = num.top();

							num.pop();

							int nx = num.top();

							num.pop();

							num.push(calculate(nx, nh, sym.top()));

							sym.pop();

						}

						sym.push(s[j]);

					}

					else

						sym.push(s[j]);

				}

			}

		}

		while (!sym.empty())

		{

			int nh = num.top();

			num.pop();

			int nx = num.top();

			num.pop();

			num.push(calculate(nx, nh, sym.top()));

			sym.pop();

		}

		if (num.top() == 24)

			cout << "Yes" << endl;

		else

			cout << "No" << endl;

	}

	return 0;

}