20. Valid Parentheses ★
题目内容:
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.
题目分析:有字符串的性质可以分析出,可以用栈来存储字符串中的每个字符,过程类似于自动机中的下推自动机。
题目代码: