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:
1 def minDepth( root): 2 if root==None: 3 return 0 4 if root.left==None or root.right==None: 5 return max(self.minDepth(root.left), self.minDepth(root.right))+1 6 return min(self.minDepth(root.left), self.minDepth(root.right))+1