(UVA

链接：https://vjudge.net/problem/UVA-673
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：输入一个包含”()”和”[]”的括号字符串，判断是否合法。
规则：1.空串合法
2.如果A和B合法，则AB合法
3.如果A合法则[A]和(A)合法

分析：按照规则用栈来写， 输入的时候要注意 用gets()输入，并且要读掉换行符！ scanf输出会WA

#include<cstdio>#include<cstring>#include<stack>#include<algorithm>using namespace std;const int N=150+5;char str[N];stack<char>st;bool paired(char ch1,char ch2){    if(ch1=='('&&ch2==')'||ch1=='['&&ch2==']')        return true;    return false;}bool solve(char *s){    while(!st.empty())        st.pop();    int len=strlen(s);    if(len&1) return false;    if(len==0) return true;    for(int i=0;i<len;i++)    {        if(!st.empty()&&paired(st.top(),s[i]))            st.pop();        else st.push(s[i]);    }    return st.empty();}int main(){    int t;    scanf("%d",&t);    getchar();    while(t--)    {        gets(str);        bool ans=solve(str);        printf("%s\n",ans?"Yes":"No");    }    return 0;}