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,
(c) if A is correct, (A) and [A] is correct.
Write a program that takes a sequence of strings of this type and check their correctness. Your program 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 string a line.
Output
A sequence of ‘Yes’ or ‘No’ on the output file.
Sample Input
3
([])
(([()])))
([()[]()])()
Sample Output
Yes
No
Yes
#include<iostream>
#include<stack>
#include<cstring>
using namespace std;
int main()
{
int t;
cin>>t;
getchar();//吸收空行
while(t--)
{
stack<char> q;
int flag=1;
string s;
getline(cin,s);//有空串,必须按行输入
for(int i=0;i<s.size();i++)
{
if(s[i]=='('||s[i]=='[')
q.push(s[i]);
else if(s[i]==')'&&!q.empty()&&q.top()=='(')//注意q.top条件必须在最后
q.pop();
else if(s[i]==']'&&!q.empty()&&q.top()=='[')
q.pop();
else flag=0;
}
if(flag&&q.empty())cout<<"Yes"<<endl;
else cout<<"No"<<endl;
while(!q.empty()) q.pop();//清空栈
}
return 0;
}