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authorVincent Ambo <mail@tazj.in>2021-12-13T22·51+0300
committerVincent Ambo <mail@tazj.in>2021-12-13T23·15+0300
commit019f8fd2113df4c5247c3969c60fd4f0e08f91f7 (patch)
tree76a857f61aa88f62a30e854651e8439db77fd0ea /users/wpcarro/scratch/facebook/interview-cake/bst-checker.py
parent464bbcb15c09813172c79820bcf526bb10cf4208 (diff)
parent6123e976928ca3d8d93f0b2006b10b5f659eb74d (diff)
subtree(users/wpcarro): docking briefcase at '24f5a642' r/3226
git-subtree-dir: users/wpcarro
git-subtree-mainline: 464bbcb15c09813172c79820bcf526bb10cf4208
git-subtree-split: 24f5a642af3aa1627bbff977f0a101907a02c69f
Change-Id: I6105b3762b79126b3488359c95978cadb3efa789
Diffstat (limited to 'users/wpcarro/scratch/facebook/interview-cake/bst-checker.py')
-rw-r--r--users/wpcarro/scratch/facebook/interview-cake/bst-checker.py14
1 files changed, 14 insertions, 0 deletions
diff --git a/users/wpcarro/scratch/facebook/interview-cake/bst-checker.py b/users/wpcarro/scratch/facebook/interview-cake/bst-checker.py
new file mode 100644
index 000000000000..bbd52fa9c64c
--- /dev/null
+++ b/users/wpcarro/scratch/facebook/interview-cake/bst-checker.py
@@ -0,0 +1,14 @@
+def is_valid(node):
+    """
+    Return True if `node` is a valid binary search tree.
+    """
+    s = []
+    s.append((float('-inf'), node, float('inf')))
+    while s:
+        lo, node, hi = s.pop()
+        if lo <= node.value <= hi:
+            node.lhs and s.append((lo, node.lhs, node.value))
+            node.rhs and s.append((node.value, node.rhs, hi))
+        else:
+            return False
+    return True