673 - Parentheses Balance

  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,

(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 

YesNoYes

题意：给一堆括号，让你判断是否能够组合

就是简单的栈的利用，把左半边的括号入栈，遇到右半边与其匹配。不过要注意到最后要判断是否为空栈。还有就是字符串当中可能有空格。

#include<iostream>#include<cstdio>#include<cmath>#include<stack>#include<cstring>using namespace std;int main (){    int n,len,i;    char str[130],temp;    cin>>n;    getchar();    while(n--)    {        bool flag=true;        stack<char> s;        gets(str);        len=strlen(str);        for (i=0; i<len; i++)            if (str[i]==' ') ;            else            {                if (!flag) break;                if (str[i]=='(' || str[i]=='[') s.push(str[i]);                else                {                    if (s.empty())                    {                        flag=false;                        break;                    }                    else                    {                        temp=s.top();                        s.pop();                        if ((str[i]==')' && temp=='(') || (str[i]==']' && temp=='[' ) ) ;                        else                        {                            flag=false;                            break;                        }                    }                }            }        if (!s.empty()) flag=false;        if (flag) cout<<"Yes"<<endl;        else cout<<"No"<<endl;    }    return 0;}