判断是否为搜索二叉树python实现

搜索二叉树为中序遍历升序判断

通过改变非递归版本的打印行为部分即可

import sys
class Node(object):
    def __init__(self,val=None):
        self.val = val
        self.left = None
        self.right = None

#非递归版本
#中序遍历把打印的时机换成比较

def isBST(head):
    if not head:
        return True
    stack = []
    pre = -sys.maxsize
    while stack or head != None:
        if head != None:
            stack.append(head)
            head = head.left
        else:
            head = stack.pop()
            print(head.val, end=' ')
            if head.val>pre:
                pre = head.val
                head = head.right
            else:
                return False
    return True



if __name__ == '__main__':
    head = Node(5)
    head.left = Node(3)
    head.left.left = Node(2)
    head.left.right = Node(4)
    head.right = Node(8)
    head.right.left = Node(6)
    head.right.right = Node(10)
    a = isBST(head)
    print(a)