Parentheses Balance

You are given a string consisting of parentheses () and []. Astring 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 checktheir correctness. Your program can assume that the maximum stringlength is 128.

Input

The file contains a positive integer
n and a sequence of
n strings ofparentheses
() 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: 匹配小括号和中括号~

做法及其注意点:

一种情况是遇到 '(' 或 '[', 那么直接放到栈里不解释~

另一种情况是遇到 ')' 或 ']', 进行判定, 是否前一个是 '(' 或 '[' (注意了, 此时栈也许是空的), 若是, 弹出栈~

最后判断是否为空~

AC代码:

#include<stdio.h>

#include<stack>

using namespace std;

int main() {

    int T;

    char ch;

    scanf("%d", &T);

    getchar();

    while(T--) {

        stack <char> sta;

        while(scanf("%c", &ch)) {

            if(ch == '\n')

                break;

            if(sta.empty()) {

                sta.push(ch);

                continue;

            }

            if(ch == '(')

                sta.push(ch);

            if(ch == ')') {

                if(sta.top() == '(')

                    sta.pop();

                else

                    sta.push(ch);

            }

            if(ch == '[')

                sta.push(ch);

            if(ch == ']') {

                if(sta.top() == '[')

                    sta.pop();

                else

                    sta.push(ch);

            }

        }

        if(sta.empty())

            printf("Yes\n");

        else

            printf("No\n");

    }

    return 0;

}