Sliding Window Pattern: How to Turn Nested Loops Into Linear Time
Learn when to use sliding windows, how fixed and variable windows differ, and how to solve classic substring and subarray problems efficiently.
sliding-window
arrays
strings
patterns
Coding interview patterns & LeetCode walkthroughs
Practical guides to the algorithm patterns that show up in real interviews.
Binary Search Pattern: More Than Just Finding a Number
Understand classic binary search, boundary search, and the broader decision-based pattern that helps solve optimization problems in logarithmic time.
binary-search
arrays
algorithms
patterns
Prefix Sums Pattern: The Simplest Way to Answer Range Queries Fast
Learn how prefix sums turn repeated range calculations from linear work into constant-time queries, and see how the pattern extends to hash maps and subarray problems.
prefix-sum
arrays
hash-map
patterns
Monotonic Stack Pattern: The Trick Behind Next Greater Element Problems
See how monotonic stacks help solve next greater, previous smaller, and histogram-style problems in linear time without brute force.
monotonic-stack
stacks
arrays
patterns
Backtracking Pattern: How to Generate Combinations Without Losing Your Mind
Learn the recursive choose-explore-unchoose pattern behind subsets, permutations, combinations, and many classic search problems.
backtracking
recursion
search
patterns
Dynamic Programming Pattern: How to Spot Overlapping Subproblems Early
A practical guide to recognizing dynamic programming problems, choosing states, and moving from brute force recursion to memoization and tabulation.
dynamic-programming
recursion
optimization
patterns
BFS vs DFS: Choosing the Right Graph Traversal for the Job
Understand the difference between breadth-first and depth-first search, when each traversal is the right fit, and how they show up in trees, graphs, and grids.
graphs
bfs
dfs
traversal
Heap Pattern: When a Priority Queue Beats Sorting Everything
Learn when heaps are the right data structure, how min-heaps and max-heaps work, and why they shine in top-k and streaming problems.
heap
priority-queue
top-k
data-structures
Union-Find Pattern: The Cleanest Way to Track Connected Components
Understand disjoint set union, path compression, and union by rank so you can solve connectivity problems efficiently.
union-find
graphs
connectivity
data-structures
Topological Sort: The Pattern for Dependency Ordering Problems
Learn how topological sorting works, why it only applies to DAGs, and how to solve course scheduling and dependency ordering problems.
topological-sort
graphs
dag
dependencies
Two Pointers Pattern: A Visual Guide to Solving Array Problems
Learn how the two pointers technique works, when to use it, and walk through classic problems like Two Sum II and Container With Most Water.
two-pointers
arrays
leetcode
patterns
Ready to practice these patterns?
Turn any LeetCode problem into an interactive lesson — trace variables, visualize the algorithm, and practice until it clicks.
Start a free lesson