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Update bst_is_valid.py

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bt3gl 2023-08-08 16:05:32 -07:00 committed by GitHub
parent f8dc224ae5
commit e0ef50da5b
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1 changed files with 18 additions and 20 deletions
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38
trees/bst_is_valid.py
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@ -3,26 +3,14 @@
# author: bt3gl # author: bt3gl
def is_valid_bst_recursive(root):
def is_valid(root, min_val=float(-inf), max_val=float(inf)):
if root is None:
return True
return (min_val < root.val < max_val) and \
is_valid(root.left, min_val, root.val) and \
is_valid(root.right, root.val, max_val)
return is_valid(root)
def is_valid_bst_iterative(root): def is_valid_bst_iterative(root):
queue = deque() queue = deque((root, float(-inf), float(inf)))
queue.append((root, float(-inf), float(inf)))
while queue: while queue:
node, min_val, max_val = queue.popleft() node, min_val, max_val = queue.popleft()
if node: if node:
if min_val >= node.val or node.val >= max_val: if min_val >= node.val or node.val >= max_val:
return False return False
@ -34,6 +22,16 @@ def is_valid_bst_iterative(root):
return True return True
def is_valid_bst_recursive(root, min_val=float(-inf), max_val=float(inf)):
if root is None:
return True
return (min_val < root.val < max_val) and \
is_valid_bst_recursive(root.left, min_val, root.val) and \
is_valid_bst_recursive(root.right, root.val, max_val)
def is_valid_bst_inorder(root): def is_valid_bst_inorder(root):
def inorder(node): def inorder(node):
@ -41,14 +39,14 @@ def is_valid_bst_inorder(root):
return True return True
inorder(node.left) inorder(node.left)
queue.append(node.val) stack.append(node.val)
inorder(node.right) inorder(node.right)
queue = [] stack = []
inorder(root) inorder(root)
for i in range(1, len(queue)):
if queue[i] <= queue[i-1]: for i in range(1, len(stack)):
if queue[i] <= queue[i - 1]:
return False return False
return True return True