Leetcode valid-parentheses

https://leetcode.com/problems/valid-parentheses/

很简单的括号匹配判断，使用栈即可。

学过数据结构或者编译原理会很容易搞

#include <cstdio>
#include <cstring>
#include <algorithm>
#include <iostream>
#include <stack>

using namespace std;

class Solution {
public:
    bool isValid(string s) {
        stack <char> sta;
        for(int i=0;i<s.size();i++) {
            //sta.push(s[i]);
            if(s[i] == '(' ||
                s[i] == '{' ||
                s[i] == '[') {
                sta.push(s[i]);
               } else {
                    if(s[i] == ')' && sta.size()>0 && sta.top() == '(' ||
                        s[i]=='}' && sta.size()>0 && sta.top()=='{' ||
                        s[i]==']' && sta.size()>0 && sta.top()=='[') sta.pop();
                    else
                        return false;

               }
        }
        if(sta.size() > 0)return false;
        else return true;
    }
};

int main() {
    Solution s;
    string str;
    while(cin >> str) {
        cout << s.isValid(str) << endl;
    }
    return 0;
}