Parentheses Balance---栈

Time limit3000 ms

STL

来源：vjudge：B-B

Description

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

题意：

第一行输入一个数n，表示接下来有n行

输入包含'(' ')' '[' ']'的字符串，如果能够组成完整，则输出"Yes",否则输出"No",但是要注意，当输入换行时，要输出"Yes";
解题思路：

因为那天几天正在讲区间DP，正好有模板，然后就拿着模板改了一下就交，然后......毫无意外的TLE了！唉，，后来用栈做的，其实很简单有木有？zz！！！其实如果当时用栈的话，，你可能也写不出来@_@!!

完整代码：

#include<stdio.h>
#include<string.h>
#include<stack>
#include<algorithm>
using namespace std;
int main()
{
    int n;
    scanf("%d",&n);
    getchar();
    while(n--)
    {
        stack<char>s;
        char a[130];
        int flag=1;
        gets(a);
        int l=strlen(a);
        if(strcmp(a,"\n")==0)///哈哈哈！你又学到一个小东西！！
        {
            flag=1;
            continue;
        }
        for(int i=0;i<l;i++)
        {
            if(a[i]=='('||a[i]=='[')
                s.push(a[i]);
            else if(a[i]==')')
            {
                if(!s.empty()&&s.top()=='(')
                    s.pop();
                else
                {
                    flag=0;
                    break;
                }
            }
            else if(a[i]==']')
            {
                if(!s.empty()&&s.top()=='[')
                    s.pop();
                else
                {
                    flag=0;
                    break;
                }
            }
         }
         if(flag==0||!s.empty())
            printf("No\n");
         else
            printf("Yes\n");
    }
    return 0;
}