LeetCode - 20. Valid Parentheses

20. Valid Parentheses

Problem's Link

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[b]Mean:[/b]

给定一个括号序列，检查括号是否按顺序匹配.

[b]analyse:[/b]

栈结构的基本运用.

[b]Time complexity: O(N)[/b]

[b]view code[/b]

/**
* -----------------------------------------------------------------
* Copyright (c) 2016 crazyacking.All rights reserved.
* -----------------------------------------------------------------
* Author: crazyacking
* Date : 2016-02-17-16.33
*/
#include <queue>
#include <cstdio>
#include <set>
#include <string>
#include <stack>
#include <cmath>
#include <climits>
#include <map>
#include <cstdlib>
#include <iostream>
#include <vector>
#include <algorithm>
#include <cstring>
using namespace std;
typedef long long(LL);
typedef unsigned long long(ULL);
const double eps(1e-8);

class Solution
{
public:
bool isValid(string s)
{
stack<char> sta;
for(auto p:s)
{
if(p=='(' || p=='{' || p=='[')
sta.push(p);
else if(p==')')
{
if(sta.empty()) return false;
char tp=sta.top();
sta.pop();
if(tp!='(')
return false;
}
else if(p=='}')
{
if(sta.empty()) return false;
char tp=sta.top();
sta.pop();
if(tp!='{')
return false;
}
else
{
if(sta.empty()) return false;
char tp=sta.top();
sta.pop();
if(tp!='[')
return false;
}
}
if(sta.empty())
return true;
else return false;
}
};

int main()
{
Solution solution;
string s;
while(cin>>s)
{
if(solution.isValid(s))
cout<<"Yes."<<endl;
else cout<<"No."<<endl;
}
return 0;
}
/*

*/