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Week 1 # E Parentheses Balance
原题描述:
E - 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
Yes
No
Yes
题目就是想让我们判断一下两种括号是否平衡。注意空字符也是平衡的。
这里要判断换行输出Yes,就要用getline(cin,a).还要注意的是,前面几组数据那里也有个换行。要用getchar()消除掉;然后就是栈的应用了。
AC代码:
1 #include <iostream> 2 #include <stack> 3 #include <string.h> 4 #include <stdio.h> 5 using namespace std; 6 int main() 7 { 8 int t; 9 cin>>t; 10 getchar(); 11 while (t--) 12 { 13 string a; 14 stack<char> c; 15 getline(cin,a); 16 if(a[0]==‘\n‘) {cout<<"Yes"<<endl;continue;} 17 c.push(‘1‘); 18 for(int i=0;i<a.size();i++) 19 { 20 if (a[i]==‘(‘||a[i]==‘[‘) c.push(a[i]); 21 else if (a[i]==‘)‘) 22 { 23 if(c.top()==‘(‘) c.pop(); 24 else c.push(‘0‘); 25 } 26 else 27 { 28 if (c.top()==‘[‘) c.pop(); 29 else c.push(‘0‘); 30 } 31 } 32 if(c.top()==‘1‘)cout<<"Yes"<<endl; 33 else cout<<"No"<<endl; 34 35 } 36 return 0; 37 }
Week 1 # E Parentheses Balance