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Floor and Ceil from a BST

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Floor and Ceil from a BST

Asha only reaches for Floor and Ceil from a BST when folder on disk has to stay correct in a file explorer.

For Floor and Ceil from a BST, a dry-run table is in play. Don’t blame it until you have traced folder on disk.

Floor and Ceil from a BST exists so Asha can keep folder on disk correct in a file explorer.

Floor and Ceil from a BST shows up in a file explorer. Name folder on disk, not “a real-world scenario”.

Don’t do this with Floor and Ceil from a BST: unbalanced BST becoming a list. Interviewers spot it in ten seconds.

Place Floor and Ceil from a BST next to nearby DSA work — left < root < right is the link.

Viva for Floor and Ceil from a BST — what it is → left < root < right → the mistake (unbalanced BST becoming a list).

Diagram

Exam tip

Board: folder on disk. Dry-run Floor and Ceil from a BST. Name the trap: unbalanced BST becoming a list.

Example

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

def insert(root, val):
    if root is None:
        return Node(val)
    if val < root.val:
        root.left = insert(root.left, val)
    elif val > root.val:
        root.right = insert(root.right, val)
    return root

root = None
for v in [5, 2, 7, 1]:
    root = insert(root, v)
print(root.val, root.left.val, root.right.val)

Floor and Ceil from a BST — bST invariant: left < node < right — enables log-time search when balanced.

Short notes

DefFloor and Ceil from a BST — Asha uses it for folder on disk in a file explorer.
RuleFloor and Ceil from a BST → left < root < right.
RememberFloor and Ceil from a BST + a dry-run table (a file explorer).
UseFloor and Ceil from a BST in a file explorer (folder on disk).
TrapFloor and Ceil from a BST — unbalanced BST becoming a list.
ExFloor and Ceil from a BST → folder on disk.

class Node: def __init__(self, val): self.val = val self.left = None self.right = None def insert(root, val): if root is None: return Node(val) if val < root.val: root.left = insert(root.left, val) elif val > root.val: root.right = insert(root.right, val) return root root = None for v in [5, 2, 7, 1]: root = insert(root, v) print(root.val, root.left.val, root.right.val)

Floor and Ceil from a BST

Example

Short notes

Questions

Floor and Ceil from a BST

Example

Short notes

Questions