minimum_depth_of_binary_tree.py

# Definition for a binary tree node.
# class TreeNode:
# def __init__(self, val=0, left=None, right=None):
# self.val = val
# self.left = left
# self.right = right

defmin_depth(root, current_depth):

ifnotroot:
return0

####################################################
# Similar to the [Recursion] approach to find the maximum depth, 
# but make sure you consider these cases:
# Node that has one empty sub-tree while the other one is non-empty. 
# Return the minimum depth of that non-empty sub-tree.
ifnotroot.left:
returnmin_depth(root.right, current_depth) +1;
ifnotroot.right:
returnmin_depth(root.left, current_depth) +1;
####################################################

# recursive (left and right)
left_depth=min_depth(root.left, current_depth)
right_depth=min_depth(root.right, current_depth)
current_depth=min( left_depth, right_depth) +1

returncurrent_depth


classSolution:
defminDepth(self, root: TreeNode) ->int:

returnmin_depth(root, 0)