leetcode-20. Valid Parentheses

Given a string containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid. The brackets must close in the correct order, "()" and "()[]{}" are all valid but "(]" and "([)]" are not. Subscribe to see which companies asked this question.

栈的使用，明白pop是不要参数的，直接p.pop( )

class Solution { public: bool isValid(string s) { stack<char> p; for(int i = 0; i < s.size(); ++i){ if(s[i] == '(' || s[i] == '[' || s[i] == '{') p.push(s[i]); else{ if(p.empty()) return false; if(s[i] == ')' && p.top() != '(') return false; if(s[i] == ']' && p.top() != '[') return false; if(s[i] == '}' && p.top() != '{') return false; else p.pop(); //栈的操作，pop的时候直接pop就行，不用加参数 } } if(p.empty()) return true; else return false; } };