新手

#include <iostream> 
using namespace std;
#include <string.h>
#include <stack>

char s[260];

stack <char> st;

int main ()
{
	int n;
	scanf ("%d", &n);
	for (int j = 0; j < n; j++)
	{
		int flag = 0;//标记
		scanf ("%s", s);
		int len = strlen(s);
		for (int i = 0; i < len; i++)
		{
			if (!st.empty() ) 
			{
				char now = st.top() ;
				if (   now == '<' && s[i] != '<' && s[i] != '>'
					|| now == '(' && s[i] != '(' && s[i] != ')' && s[i] != '<' && s[i] != '>' 
					|| now == '[' && (s[i] == '{' || s[i] == '}'))//优先级问题
				{
					flag = 1;//当优先级顺序出现问题时，标记为1，输出NO
					break;
				}
				else if (now == '(' && s[i] == ')' || now == '[' && s[i] == ']' 
                      || now == '{' && s[i] == '}' || now == '<' && s[i] == '>')//匹配问题
					st.pop() ;	
				else st.push(s[i]) ;
			}
			else st.push(s[i...