56 lines
1017 B
Python
56 lines
1017 B
Python
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class TreeNode:
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def __init__(self, val):
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self.val = val
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self.left = None
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self.right = None
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def validateBST(root):
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if not root:
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return True
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# check BST conditions for current node
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validBST = True
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if root.left and not root.left.val < root.val:
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validBST = False
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if root.right and not root.right.val > root.val:
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validBST = False
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leftRes = validateBST(root.left)
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rightRes = validateBST(root.right)
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return validBST and leftRes and rightRes
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# # 5
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# # 3 7
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# # 2 4 6 8
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# root = TreeNode(5)
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# root.left = TreeNode(3)
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# root.right = TreeNode(7)
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# root.left.left = TreeNode(2)
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# root.left.right = TreeNode(4)
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# root.right.left = TreeNode(6)
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# root.right.right = TreeNode(8)
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# [10,5,15,null,null,6,20]
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# # 10
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# # 5 15
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# # X X 6 20
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root = TreeNode(10)
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root.left = TreeNode(5)
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root.right = TreeNode(15)
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root.right.left = TreeNode(6)
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root.right.right = TreeNode(20)
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print(validateBST(root))
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