python
# Definition for a binary tree node.
# class TreeNode:
# def __init__(self, val=0, left=None, right=None):
# self.val = val
# self.left = left
# self.right = right
class Solution:
def findMode(self, root: Optional[TreeNode]) -> List[int]:
self.mode = []
self.curCount = 0
self.maxCount = 0
self.prev = None
self.traverse(root)
return self.mode
def traverse(self, root):
if not root:
return
self.traverse(root.left)
if not self.prev:
self.curCount = 1
self.maxCount = 1
self.mode.append(root.val)
else:
if root.val == self.prev.val:
self.curCount += 1
# root.val 是众数
if self.curCount == self.maxCount:
self.mode.append(root.val)
elif self.curCount > self.maxCount:
# 更新众数
self.mode.clear()
self.maxCount = self.curCount
self.mode.append(root.val)
if root.val != self.prev.val:
# root.val 不重复的情况
self.curCount = 1
if self.curCount == self.maxCount:
self.mode.append(root.val)
# 更新prev
self.prev = root
self.traverse(root.right)