104. Maximum Depth of Binary Tree

问题描述

Given a binary tree, find its maximum depth.
The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.

思路

用recursive的方法，一层层往下call，最后从下往上返回每两个同parent的nodes中的较大值+1,得到maximum depth

  def maxDepth(self, root):
      """
      :type root: TreeNode
      :rtype: int
      """
      left=1
      right=1
      if not root:
          return 0
      if(root.left):
          left=1+self.maxDepth(root.left)
      if(root.right):
          right=1+self.maxDepth(root.right)
      return max(left,right)