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70 categories covering 2808 problems
Each topic hub includes difficulty mix, progression hints, and related patterns for targeted improvement.
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array
363876433·1672
string
212329158·699
hash table
155349106·610
dynamic programming
12249268·529
math
142243143·528
sorting
8123386·400
greedy
4524785·377
binary search
26135104·265
depth first search
3614868·252
matrix
3712559·221
bit manipulation
459778·220
breadth first search
1912256·197
tree
3810548·191
prefix sum
1911354·186
two pointers
5410424·182
simulation
758511·171
heap priority queue
159361·169
counting
567716·149
graph
36672·141
stack
237542·140
sliding window
187837·133
binary tree
358510·130
enumeration
265834·118
design
106024·94
backtracking
35827·88
union find
14033·74
number theory
113032·73
linked list
12477·66
ordered set
32135·59
segment tree
11145·57
monotonic stack
22923·54
combinatorics
31432·49
bitmask
01235·47
trie
32220·45
divide and conquer
52413·42
memoization
31127·41
queue
61916·41
recursion
101713·40
geometry
91712·38
binary indexed tree
0825·33
string matching
10815·33
hash function
41017·31
binary search tree
9182·29
shortest path
01613·29
topological sort
01018·28
rolling hash
1915·25
game theory
3129·24
monotonic queue
0711·18
brainteaser
2131·16
data stream
364·13
randomized
093·12
counting sort
540·9
doubly linked list
144·9
merge sort
027·9
quickselect
070·7
bucket sort
051·6
line sweep
015·6
probability and statistics
051·6
interactive
212·5
iterator
050·5
suffix array
005·5
reservoir sampling
040·4
eulerian circuit
003·3
minimum spanning tree
012·3
radix sort
030·3
strongly connected component
003·3
rejection sampling
020·2
sort
011·2
biconnected component
001·1
hash map
100·1