Problems
| # | Title | Difficulty | Tags |
|---|---|---|---|
| 1 | Print Linked List in Reverse |
linkedlist
recursion
stack
|
|
| 2 | Subset Sum Count |
recursion
dynamicprogramming
backtracking
|
|
| 3 | Sort Three Integers |
algorithm
sorting
|
|
| 4 | Best Grid Dimensions |
math
|
|
| 5 | Rotate Image (Matrix 90°) |
matrix
array
|
|
| 6 | Reverse String |
string
twopointers
|
|
| 7 | Clock Angle |
math
|
|
| 8 | Random 7 from Random 5 |
math
probability
rejectionsampling
|
|
| 9 | Level Order Traversal |
tree
bfs
queue
|
|
| 10 | Spiral Matrix Traversal |
matrix
simulation
|
|
| 11 | Find All Primes |
math
sieveoferatosthenes
|
|
| 12 | Connect Next Right Pointers in Tree |
tree
bfs
|
|
| 13 | Middle of Linked List |
linkedlist
twopointers
|
|
| 14 | Find Odd Occurrence |
bitmanipulation
array
|
|
| 15 | Reverse Linked List |
linkedlist
recursion
|
|
| 16 | Flood Fill |
graph
dfs
bfs
matrix
|
|
| 17 | Remove Duplicates from Sorted Array |
array
twopointers
|
|
| 18 | Integer Division without Operators |
bitmanipulation
math
|
|
| 19 | Evaluate Expression Tree |
tree
recursion
|
|
| 20 | Detect Cycle in Directed Graph |
graph
dfs
topologicalsort
|
|
| 21 | Roman to Integer |
string
math
hashtable
|
|
| 22 | Huffman Encoding |
tree
greedy
heap
|
|
| 23 | Maximum Subarray Sum |
array
dynamicprogramming
divideandconquer
|
|
| 24 | Valid Anagram |
string
hashtable
sorting
|
|
| 25 | Reservoir Sampling |
algorithm
probability
randomization
|
|
| 26 | Product of Array Except Self |
array
prefixsum
|
|
| 27 | Two Sum |
array
hashtable
|
|
| 28 | Evaluate Reverse Polish Notation |
stack
math
|
|
| 29 | Word Ladder |
graph
bfs
string
|
|
| 30 | First Duplicate Character |
string
hashtable
|
|
| 31 | Find First One in Infinite Stream |
binarysearch
exponentialsearch
|
|
| 32 | Reverse String Recursively |
string
recursion
|
|
| 33 | Fibonacci Number |
recursion
dynamicprogramming
math
|
|
| 34 | Count Set Bits (Population Count) |
bitmanipulation
|
|
| 35 | Maximum Gap (Bucket Sort) |
array
bucketsort
sorting
|
|
| 36 | Word Count |
string
|
|
| 37 | Implement Trie (Prefix Tree) |
trie
design
datastructure
|
|
| 38 | Array Intersection |
array
hashtable
sorting
|
|
| 39 | Power of Two |
bitmanipulation
math
|
|
| 40 | Search 2D Matrix |
matrix
binarysearch
divideandconquer
|
|
| 41 | Priority Queue (Binary Heap) |
heap
datastructure
design
|
|
| 42 | Power Set (All Subsets) |
bitmanipulation
recursion
backtracking
|
|
| 43 | Maximum Element in Array |
array
|
|
| 44 | Best Matching Substring (Frequency Analysis) |
string
slidingwindow
array
|
|
| 45 | Min Stack (Stack with getMax) |
stack
design
|
|
| 46 | Maximum Bandwidth (Weighted Interval Overlap) |
array
sorting
sweepline
|
|
| 47 | Minimum Notification Time (Tree Broadcast) |
tree
greedy
dfs
|
|
| 48 | Edit Distance (Levenshtein Distance) |
dynamicprogramming
string
|
|
| 49 | Swap Variables Without Temp |
bitmanipulation
math
|
|
| 50 | Find Duplicate Number |
array
twopointers
cycledetection
|
|
| 51 | String Permutations |
string
recursion
backtracking
|
|
| 52 | Implement strstr (Find Substring) |
string
twopointers
|
|
| 53 | Fisher-Yates Shuffle |
array
randomization
|
|
| 54 | Traffic Sensor Matching |
array
twopointers
greedy
|