# ---
# title: 111. Minimum Depth of Binary Tree
# id: problem111
# author: Tian Jun
# date: 2020-10-31
# difficulty: Easy
# categories: Tree, Depth-first Search, Breadth-first Search
# link: <https://leetcode.com/problems/minimum-depth-of-binary-tree/description/>
# hidden: true
# ---
# 
# Given a binary tree, find its minimum depth.
# 
# The minimum depth is the number of nodes along the shortest path from the root
# node down to the nearest leaf node.
# 
# **Note:**  A leaf is a node with no children.
# 
# 
# 
# **Example 1:**
# 
# ![](https://assets.leetcode.com/uploads/2020/10/12/ex_depth.jpg)
# 
#     
#     
#     Input: root = [3,9,20,null,null,15,7]
#     Output: 2
#     
# 
# **Example 2:**
# 
#     
#     
#     Input: root = [2,null,3,null,4,null,5,null,6]
#     Output: 5
#     
# 
# 
# 
# **Constraints:**
# 
#   * The number of nodes in the tree is in the range `[0, 105]`.
#   * `-1000 <= Node.val <= 1000`
# 
# 
## @lc code=start
using LeetCode

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