LeetCode#111 Minimum Depth of Binary Tree

Problem Definition:

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.

Solution:

def minDepth( root):
if root==None:
return 0
if root.left==None or root.right==None:
return max(self.minDepth(root.left), self.minDepth(root.right))+1
return min(self.minDepth(root.left), self.minDepth(root.right))+1