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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
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Miguel Revilla 2000-08-14
题意: 如果有一个'('那么就要有一个)与它匹配,如果有一个'['那么就要有一个']'与它匹配.。如果都满足,输出”YES“,else 输出”NO“. 思路; 建立一个栈,左括号’[‘,'('都入栈,右括号')',']'都出栈依次进行下去,如果栈为空,则满足条件,输出“YES”,如果不满足条件,则输出”NO“。 代码:
#include
#include
using namespace std; int main() { int n; scanf(%d,&n); getchar(); while(n--) { char a[130]; stack
s; gets(a); int flag=0; for(int i=0;a[i]!='';i++) { if(a[i]=='('||a[i]=='[') s.push(a[i]); else if(a[i]==')') { if(!s.empty()&&s.top()=='(') s.pop(); else {flag=1;break;} } else if(a[i]==']') { if(!s.empty()&&s.top()=='[') s.pop(); else {flag=1;break;} } } if(flag||!s.empty()) printf(No ); else printf(Yes ); } return 0; }
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