Valid Parentheses

#include<stack>#include<string>#include<iostream>using namespace std;class Solution {public:bool isValid(string s) {int length = s.size();int i = 1;stack<char> temp;if (length == 0){return false;}temp.push(s[0]);while (i< length){//cout << s[i] << endl;if (s[i] == '(' || s[i] == '[' || s[i] == '{'){//cout << "push" << s[i] << endl;temp.push(s[i]);}else{//这个上面的else很重要，因为当s[i]不是左括号时，此时栈已经空了，如果出现右边符号，就是没有匹配的左值符号，没有检测下去的必要。if (temp.empty()){return false;}else if (s[i] == ')'){if (temp.top() == '('){temp.pop();}else{return false;}}else if (s[i] == '}'){if (temp.top() != '{'){return false;}else{temp.pop();}}else if (s[i] == ']'){if (temp.top() != '['){return false;}else{temp.pop();}}}i++;}if (!temp.empty()){return false;}else{return true;}}};int main(){string s = "[])";Solution obj;bool res;res = obj.isValid(s);if (res == true){cout << "true " << endl;}else{cout << "false " << endl;;}while (1);return 1;}