DSA · Theory

Optimal binary search tree

Theory

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Optimal binary search tree

Optimal binary search tree (alt) is a DSA topic. In plain words you use it for folder on disk in a file explorer. Don’t start with a slogan — start with that picture.

Smallest example: left < root < right. Type it, run it, and say what you see. If you can do that from memory, you know Optimal binary search tree (alt).

From the example next to this theory: Optimal binary search tree (alt) — binary search halves a sorted array each step — O(log n).

Trap — unbalanced BST becoming a list. Fix that before you talk about advanced DSA.

Viva — what is Optimal binary search tree (alt)? Then show left < root < right. Then name the trap.

Diagram

Exam tip

What is Optimal binary search tree (alt)? Show this: left < root < right. Trap: unbalanced BST becoming a list.

Example

def binary_search(arr, target):
    lo, hi = 0, len(arr) - 1
    while lo <= hi:
        mid = (lo + hi) // 2
        if arr[mid] == target:
            return mid
        if arr[mid] < target:
            lo = mid + 1
        else:
            hi = mid - 1
    return -1

print(binary_search([1, 3, 5, 7, 9], 7))

Optimal binary search tree (alt) — binary search halves a sorted array each step — O(log n).

Short notes

DefOptimal binary search tree (alt) — folder on disk in a file explorer.
Ruleleft < root < right
Trapunbalanced BST becoming a list
Usea file explorer

DSA · Theory

Optimal binary search tree

← All stacks

Theory

459/810

Optimal binary search tree

Optimal binary search tree (alt) is a DSA topic. In plain words you use it for folder on disk in a file explorer. Don’t start with a slogan — start with that picture.

Smallest example: left < root < right. Type it, run it, and say what you see. If you can do that from memory, you know Optimal binary search tree (alt).

From the example next to this theory: Optimal binary search tree (alt) — binary search halves a sorted array each step — O(log n).

Trap — unbalanced BST becoming a list. Fix that before you talk about advanced DSA.

Viva — what is Optimal binary search tree (alt)? Then show left < root < right. Then name the trap.

Diagram

Exam tip

What is Optimal binary search tree (alt)? Show this: left < root < right. Trap: unbalanced BST becoming a list.

Example

def binary_search(arr, target):
    lo, hi = 0, len(arr) - 1
    while lo <= hi:
        mid = (lo + hi) // 2
        if arr[mid] == target:
            return mid
        if arr[mid] < target:
            lo = mid + 1
        else:
            hi = mid - 1
    return -1

print(binary_search([1, 3, 5, 7, 9], 7))

Optimal binary search tree (alt) — binary search halves a sorted array each step — O(log n).

Short notes

DefOptimal binary search tree (alt) — folder on disk in a file explorer.
Ruleleft < root < right
Trapunbalanced BST becoming a list
Usea file explorer

Optimal binary search tree

Example

Short notes

Questions

Optimal binary search tree

Example

Short notes

Questions