leetcode 94 二叉树的中序遍历
z
 2019-07-04 21:02:18  

给定一个二叉树，返回它的中序 遍历。

示例:

1
2
3
4
5
6
7
8
输入: [1,null,2,3]
   1
    \
     2
    /
   3

输出: [1,3,2]
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
# Definition for a binary tree node.
# class TreeNode(object):
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution(object):
    def inorderTraversal(self, root):
        """
        :type root: TreeNode
        :rtype: List[int]
        """
        ans = []
        l = []
        l.append(root)
        while l:
            p = l.pop()
            # 向l中一直添加左子树
            while p:
                l.append(p)
                p = p.left
            while l:
                p = l.pop()
                ans.append(p.val)
                if p.right:
                    l.append(p.right)
                    break
        return ans
        
        
#         def recuisive(root, ans):
#             if not root:
#                 return 
#             if root.left:
#                 recuisive(root.left, ans)
#             ans.append(root.val)
#             if root.right:
#                 recuisive(root.right, ans)
        
#         ans = []
#         recuisive(root, ans)
#         return ans