Topic hub system
LeetCode topic hubs organized for focused practice
If you want to stop practicing randomly, this is the cleaner starting point. Each hub is organized around one interview dimension with representative problems, difficulty mix, and linked patterns.
Start here
70
topic hubs
2,808
problems covered
If you are not sure where to begin, start with arrays, strings, hash tables, and dynamic programming.
Featured hubs
Start from the four most common hubs
These four hubs make the strongest first pass because they help you build representative problem paths and steadier interview rhythm.
array
Representative problems + practice order + linked patterns
A strong starting point for indexing, traversal, boundary handling, and data organization.
1,672 problems · Easy 363 / Medium 876 / Hard 433
string
Representative problems + practice order + linked patterns
Tests careful detail handling with two pointers, hashing, and sliding window combinations.
699 problems · Easy 212 / Medium 329 / Hard 158
hash table
Representative problems + practice order + linked patterns
Builds O(1) lookup instincts for counting, mapping, and deduplication problems.
610 problems · Easy 155 / Medium 349 / Hard 106
dynamic programming
Representative problems + practice order + linked patterns
Trains state definition, transition design, and trade-off articulation.
529 problems · Easy 12 / Medium 249 / Hard 268
All topics
All topic entries
Keep the full topic surface area, but use a lighter list treatment instead of repeating oversized cards.
math
sorting
greedy
binary search
depth first search
matrix
bit manipulation
breadth first search
tree
prefix sum
two pointers
simulation
heap priority queue
counting
graph
stack
Show remaining topic hubs (50)expand_more
sliding window
binary tree
enumeration
design
backtracking
union find
number theory
linked list
ordered set
segment tree
monotonic stack
combinatorics
bitmask
trie
divide and conquer
memoization
queue
recursion
geometry
binary indexed tree
string matching
hash function
binary search tree
shortest path
topological sort
rolling hash
game theory
monotonic queue
brainteaser
data stream
randomized
counting sort
doubly linked list
merge sort
quickselect
bucket sort
line sweep
probability and statistics
interactive
iterator
suffix array
reservoir sampling
eulerian circuit
minimum spanning tree
radix sort
strongly connected component
rejection sampling
sort
biconnected component
hash map
FAQ
A few questions about topic hubs
When should I use topic hubs?add
Use topic hubs when you already know the weakness you want to improve or when you want a focused run through one interview dimension.
Which topics should I start with first?add
If you do not have an obvious weakness yet, start with arrays, strings, hash tables, and dynamic programming. They build strong representative problem paths and interview rhythm.
How should topic hubs and pattern pages work together?add
Use topic hubs to isolate a weakness, then use pattern pages to extract reusable solving frames that transfer across problems.
What does each topic hub include?add
Each hub organizes representative problems, difficulty mix, linked patterns, and the next practice entry points around one topic instead of leaving you with random browsing.