剑指offer 二叉树的深度

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二叉树的深度

题目

输入一棵二叉树，求该树的深度。从根结点到叶结点依次经过的结点（含根、叶结点）形成树的一条路径，最长路径的长度为树的深度。

方法

方法1：递归

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# -*- coding:utf-8 -*-
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None
class Solution:
    def TreeDepth(self, pRoot):
        # write code here
        if not pRoot:
            return 0

        left_height=self.TreeDepth(pRoot.left)
        right_height=self.TreeDepth(pRoot.right)
        return 1+max(left_height,right_height)

方法2：非递归

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# -*- coding:utf-8 -*-
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None
class Solution:
    def TreeDepth(self, pRoot):
        # write code here
        if not pRoot:
            return 0
        stack=[(pRoot,1)]
        depth=1
        while stack:
            node,cur_depth=stack.pop()

            depth=max(depth,cur_depth)
            if node.left:
                stack.append((node.left,cur_depth+1))

            if node.right:
                stack.append((node.right,cur_depth+1))
        return depth
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# -*- coding:utf-8 -*-
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None
class Solution:
    def TreeDepth(self, pRoot):
        # write code here
        if not pRoot:
            return 0
        stack=[(pRoot,1)]
        depth=1
        while stack:
            node,cur_depth=stack.pop(0)
            if node:
                depth=max(depth,cur_depth)
                stack.append((node.left,cur_depth+1))
                stack.append((node.right,cur_depth+1))
        return depth