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Find kth Smallest Element in a Binary Search Tree

Theory

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Find kth Smallest Element in a Binary Search Tree

Find kth Smallest Element in a Binary Search Tree is a DSA idea you prove with folder on disk, not with a slogan.

Find kth Smallest Element in a Binary Search Tree on the board: left < root < right. Then say what folder on disk looks like after.

Skip Find kth Smallest Element in a Binary Search Tree and unbalanced BST becoming a list shows up in a file explorer.

Use Find kth Smallest Element in a Binary Search Tree when folder on disk must stay clear. If a simpler DSA step works, use that instead.

Don’t do this with Find kth Smallest Element in a Binary Search Tree: unbalanced BST becoming a list. Interviewers spot it in ten seconds.

Place Find kth Smallest Element in a Binary Search Tree next to nearby DSA work — left < root < right is the link.

Viva for Find kth Smallest Element in a Binary Search Tree: what it is → left < root < right → the mistake (unbalanced BST becoming a list).

Diagram

Exam tip

Say Find kth Smallest Element in a Binary Search Tree in one breath, then left < root < right, then 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))

Find kth Smallest Element in a Binary Search Tree — binary search halves a sorted array each step — O(log n).

Short notes

DefFind kth Smallest Element in a Binary Search Tree — Rohit uses it for folder on disk in a file explorer.
RuleFind kth Smallest Element in a Binary Search Tree → left < root < right.
RememberFind kth Smallest Element in a Binary Search Tree + Big-O (a file explorer).
UseFind kth Smallest Element in a Binary Search Tree in a file explorer (folder on disk).
TrapFind kth Smallest Element in a Binary Search Tree — unbalanced BST becoming a list.
ExFind kth Smallest Element in a Binary Search Tree → folder on disk.

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))

Find kth Smallest Element in a Binary Search Tree

Example

Short notes

Questions

Find kth Smallest Element in a Binary Search Tree

Example

Short notes

Questions