You are on level: Student
Overview
Quick DSA Review
Basic Algorithms
Sorted Array
Implicitly Sorted Array
Advanced
Speedrun
Core Concepts
Same Direction
Opposite Direction
Sliding Window
Prefix Sum
Cycle Finding
Decision Making
Introduction
DFS on Tree
Binary Search Tree
Combinatorial Search
Additional States
Aggregation and Memoization
Additional Practices
Speedrun
Introduction
Vanilla BFS
Matrix as Graph
Implicit Graph
Directed Graph / Topological Sort
Weighted Graph
Minimum Spanning Tree
Introduction
Top K
Moving Best
Multiple Heaps
Introduction
Constant Transition
Grid
Dual-Sequence
Non-constant Transition
Knapsack, Weight-Only
Knapsack, Weight+Value
Topological Sort
Additional Practices
Disjoint Set Union | Union Find
Data Structure Design
Segment Tree
Interval
Monotonic Stack
Tree Traversal without Recursion
Amazon OA
Microsoft OA
Google OA
Given the root node of a valid BST and a number k, return the kth smallest number
in this BST (1-indexed).
bst = <See explanation> k = 4
6
1 <= k <= n <= 10^5, where n is the size of bst.