# Definition for a binary tree node.
# class TreeNode(object):
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution(object):
    depthList=[]
    def minDepth(self, root):
        """
        :type root: TreeNode
        :rtype: int
        """
        self.depthList=[]
        if root==None:return 0
        self.depthList.append(1)
        self.dfs(root)
       
        return min(self.depthList)
        
        
    def dfs(self,root):
        
        curdepth=self.depthList[-1]
        
        if root.right!=None or root.left!=None:
            self.depthList.pop()
        else:return
        
        if root.left!=None:
            dep=curdepth+1
            self.depthList.append(dep)
            self.dfs(root.left)
        if root.right!=None:
            dep=curdepth+1
            self.depthList.append(dep)
            self.dfs(root.right)
        
        
        

        
        
    
    
       

【leetcode?python】 111. Minimum Depth of Binary Tree