501. Find Mode in Binary Search Tree

501. Find Mode in Binary Search Tree

中序遍历，得到单调递增的数组，然后记录最大次数，等于最大次数：append，大于最大次数：清空+append

class Solution(object):
    def findMode(self, root):
        """
        :type root: TreeNode
        :rtype: List[int]
        """
        stack = []
        node = root
        res = []
        maxNum = curNum = 0
        pre = None
        while stack or node:
            while node:
                stack.append(node)
                node = node.left
            if stack:
                node = stack.pop()
                if node.val != pre:
                    curNum = 0
                curNum += 1
                if curNum == maxNum:
                    if not res or node.val != res[-1]:
                        res.append(node.val)
                elif curNum > maxNum:
                    maxNum = curNum
                    res = [node.val]
                pre = node.val
                node = node.right
        return res