UVA 673 Parentheses Balance 解题心得

原题

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

分析：简单题，直接用栈就可以

我的代码：

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

char s[150];

bool ifpop(const char a, const char b)
{
    if (a == '('&&b == ')')            return 1;
    if (a == '['&&b == ']')            return 1;
    return 0;
}


int main()
{
    int t;
    cin >> t;
    getchar();
    while (t--)
    {
        stack<char> z;
        gets(s);
        if (s[0] == '')
        {
            puts("Yes");
            continue;
        }
        else
        {
            for (int i = 0;s[i]!=''; i++)
            {
                if (z.empty())
                {
                    z.push(s[i]);
                }
                else
                {
                    if (ifpop(z.top(), s[i]))
                    {
                        z.pop();
                    }
                    else
                    {
                        z.push(s[i]);
                    }
                }
            }
            if (z.empty())                puts("Yes");
            else                        puts("No");
        }

        
    }
    return 0;
}