# ---
# title: 20. Valid Parentheses
# id: problem20
# author: Tian Jun
# date: 2020-10-31
# difficulty: Easy
# categories: String, Stack
# link: <https://leetcode.com/problems/valid-parentheses/description/>
# hidden: true
# ---
# 
# Given a string `s` 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.
# 
# 
# 
# **Example 1:**
# 
#     
#     
#     Input: s = "()"
#     Output: true
#     
# 
# **Example 2:**
# 
#     
#     
#     Input: s = "()[]{}"
#     Output: true
#     
# 
# **Example 3:**
# 
#     
#     
#     Input: s = "(]"
#     Output: false
#     
# 
# **Example 4:**
# 
#     
#     
#     Input: s = "([)]"
#     Output: false
#     
# 
# **Example 5:**
# 
#     
#     
#     Input: s = "{[]}"
#     Output: true
#     
# 
# 
# 
# **Constraints:**
# 
#   * `1 <= s.length <= 104`
#   * `s` consists of parentheses only `'()[]{}'`.
# 
# 
## @lc code=start
using LeetCode

## add your code here:
## @lc code=end
