南邮 OJ 1436 Brackets

Brackets

时间限制(普通/Java) : 1000 MS/ 3000 MS 运行内存限制 : 65536 KByte

总提交 : 144 测试通过 : 35

比赛描述

There are six kinds of brackets: ‘(‘, ‘)’, ‘[‘, ‘]’, ‘{’, ‘}’. dccmx’s girl friend is now learning java programming language, and got mad with brackets! Now give you a string of brackets. Is it valid? For example:
“(([{}]))” is valid, but “([)]” is not.

输入

First line contains an integer T (T<=10): the number of test case.

Next T lines, each contains a string: the input expression consists of brackets.

The length of a string is between 1 and 100.

输出

For each test case, output “Valid” in one line if the expression is valid, or “Invalid” if not.

样例输入

2

{{[[(())]]}}

({[}])

样例输出

Valid

Invalid

题目来源

NUPT ACM 2010 Personal Ranking Contest

#include<iostream>
#include<string>
#include<stack>
using namespace std;

bool match(char c1, char c2){
if('('==c1 && ')'==c2 ||
'['==c1 && ']'==c2 ||
'{'==c1 && '}'==c2){
return 1;
}
return 0;
}
int main(){
int n,i,len;
string s;
stack<char> cStack;
cin>>n;
while(n--){
while(!cStack.empty()){
cStack.pop();
}
cin>>s;
len = s.length();
for(i=0; i<len; i++){
if('('==s[i] || '['==s[i] || '{'==s[i]){
cStack.push(s[i]);
}else if(')'==s[i] || ']'==s[i] || '}'==s[i]){
if(!cStack.empty() && match(cStack.top(),s[i]) ){
cStack.pop();
}else{
break;
}
}
}
if(i>=len && cStack.empty()){
cout<<"Valid"<<endl;
}else{
cout<<"Invalid"<<endl;
}
}
}