E - Parentheses Balance

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本文介绍了一个使用栈数据结构实现的括号匹配算法。该算法能够判断由圆括号'()'和方括号'[]'组成的字符串是否正确配对。通过逐个读取字符并利用栈进行匹配检查，程序能高效地确定输入字符串的有效性。

E - Parentheses Balance

You are given a string consisting of parentheses () and []. A string of this type is said to be correct:

(a) if it is the empty string

(b) if A and B are correct, AB is correct,

Write a program that takes a sequence of strings of this type and check their correctness. Yourprogram can assume that the maximum string length is 128.

Input

The file contains a positive integer n and a sequence of n strings of parentheses ‘()’ and ‘[]’, one stringa line.

Output

A sequence of ‘Yes’ or ‘No’ on the output file.

Sample Input

([])

(([()])))

([()[]()])()

Sample Output

Yes

代码：

#include<iostream>
#include<cstdio>
#include<stack>
using namespace std;

int main(void)
{
	stack<char> p;
	int i,j,n;
	scanf("%d",&n);
	getchar();
	while(n--)
	{
		string s1;
		getline(cin,s1);//(a) if it is the empty string
		int len=s1.length();
		for(i=0;i<len;i++)
		{
			if(p.empty())
			{
				p.push(s1.at(i));
				continue;
			}
			if((p.top()=='('&&s1.at(i)==')')||(p.top()=='['&&s1.at(i)==']'))
			{
				p.pop();
				continue;
			}
			else
			p.push(s1.at(i));
		}
		if(p.empty())
		printf("Yes\n");
		else
		printf("No\n");
		while(!p.empty())
		{
			p.pop();
		}
		s1="";
	}
	return 0;
}