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Tags: 每日算法题, 算法, 数据结构, 面试题, Daily Interview Problem, Data Structures and Algorithms, Computer Programming, Python, | English | Home Page | Category: Computing | 205 Views, 14878 Search Bots | 128 Words
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Hi, here's your problem today. This problem was recently asked by Facebook:
You are given the root of a binary search tree. Return true if it is a valid binary search tree, and false otherwise. Recall that a binary search tree has the property that all values in the left subtree are less than or equal to the root, and all values in the right subtree are greater than or equal to the root.
Here's a starting point:
Tags: 每日算法题, 算法, 数据结构, 面试题, Daily Interview Problem, Data Structures and Algorithms, Computer Programming, Python, | English | Home Page | Cateogry: Computing | 205 Views, 14878 Search Bots | 128 Words You are given the root of a binary search tree. Return true if it is a valid binary search tree, and false otherwise. Recall that a binary search tree has the property that all values in the left subtree are less than or equal to the root, and all values in the right subtree are greater than or equal to the root.
Here's a starting point:
class TreeNode:
def __init__(self, key):
self.left = None
self.right = None
self.key = key
def is_bst(root):
# Fill this in.
a = TreeNode(5)
a.left = TreeNode(3)
a.right = TreeNode(7)
a.left.left = TreeNode(1)
a.left.right = TreeNode(4)
a.right.left = TreeNode(6)
print is_bst(a)
# 5
# / \
# 3 7
# / \ /
#1 4 6
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