0020.valid-parentheses

20. Valid Parentheses

题目

Given a string containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.

An input string is valid if:

1. Open brackets must be closed by the same type of brackets.
2. Open brackets must be closed in the correct order.

Note that an empty string is also considered valid.

Example 1:

Input: "()"
Output: true

Example 2:

Input: "()[]{}"
Output: true

Example 3:

Input: "(]"
Output: false

Example 4:

Input: "([)]"
Output: false

Example 5:

Input: "{[]}"
Output: true
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.

解题思路

栈是一个后进先出的队列，用在这里可以避免复杂的判断结构。但是，Go语言的标准库没有栈这种结构，我就手动实现了一个。

总结

选用合适的数据结构，可以让程序清晰。