题目

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.

翻译

括号匹配

Hints

Related Topics: Stack, String

通过栈就可以简单实现了

代码

Java

class Solution {

    public boolean isValid(String s) {

        Stack<Character> stack = new Stack<Character>();

        for(char c : s.toCharArray()){

            if(c == '(')    stack.push(')');

            else if(c=='[') stack.push(']');

            else if(c=='{') stack.push('}');

            else if (stack.isEmpty()||stack.pop()!=c)

                return false;

        }

        return stack.isEmpty();

    }

}

Python

class Solution(object):

    def isValid(self, s):

        """

        :type s: str

        :rtype: bool

        """

        stack = []

        for i in range(len(s)):

            if s[i]=='(' or s[i]=='[' or s[i]=='{':

                stack.append(s[i])

            elif s[i]==')' or s[i]==']' or s[i]=='}':

                if len(stack)==0:   return False

                tmp = stack.pop()

                if (s[i]==')' and tmp!='(') or (s[i]==']' and tmp!='[') or (s[i]=='}' and tmp!='{'):

                    return False

        if len(stack)!=0:

            return False

        return True