leetcode—Valid Parentheses

1.问题描述

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.

2.解法分析

典型的栈用法。

class Solution { public: bool isValid(string s) { // Start typing your C/C++ solution below // DO NOT write int main() function vector<char> myStack; map<char,char>dict; dict.insert(make_pair('(',')')); dict.insert(make_pair('[',']')); dict.insert(make_pair('{','}')); for(int i=0;i<s.length();++i) { if(s[i]=='('||s[i]=='['||s[i]=='{')myStack.push_back(s[i]); else if(s[i]==')'||s[i]==']'||s[i]=='}') { if(myStack.empty())return false; if(dict[myStack.back()]==s[i])myStack.pop_back(); else return false; } } if(myStack.empty())return true; return false; } };