题解 | 二叉树的最小深度

# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None
#
# 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
#
# 
# @param root TreeNode类 
# @return int整型
#
class Solution:
    def run(self , root: TreeNode) -> int:
        # write code here
        if not root:
            return 0
        left_h=self.run(root.left)
        right_h=self.run(root.right)
        if left_h==0:
            return right_h+1
        if right_h==0:
            return left_h+1
        return min(left_h,right_h)+1