Programming questions
Build working solutions. Test edge cases. Understand the algorithm.
Sum or Product
python_basics · functions
Positive and Even
python_basics · control_flow
String Reversal
strings · python_basics
Compound Interest
python_basics · arithmetic · finance
Integer Search
arrays · binary_search
Non-Adjacent Sum
arrays · dynamic_programming
Maximum Profit Trades
arrays · greedy
Maximum Drawdown
arrays · running_extrema · finance
Decreasing Prices
arrays · binary_search · dynamic_programming
Dijkstra: Shortest Path
graphs · heaps · shortest_path
Frequency Counter in First-Seen Order Premium
arrays · hash_maps · counting
Balanced Brackets Premium
strings · stacks
Merge Two Sorted Arrays Premium
arrays · two_pointers
Two Sum with a Deterministic Pair Premium
arrays · hash_maps
Longest Substring without Repeated Characters Premium
strings · hash_maps · sliding_window
Maximum Subarray with Stable Boundaries Premium
arrays · dynamic_programming
Product Except Self Modulo M Premium
arrays · prefix_suffix · modular_arithmetic
Merge Overlapping Closed Intervals Premium
arrays · sorting · intervals
Lower and Upper Binary-Search Boundaries Premium
arrays · binary_search
Top K Frequent Values with Tie-Breaking Premium
hash_maps · heaps · sorting
Kth Largest Element Including Duplicates Premium
arrays · heaps · selection
Time-Window Moving Average Premium
queues · streaming · time_series
Maximum Depth of an Indexed Binary Tree Premium
trees · depth_first_search · stacks
Level Order of an Indexed Binary Tree Premium
trees · breadth_first_search · queues
Count Undirected Connected Components Premium
graphs · depth_first_search
Shortest Open Path across a Grid Premium
graphs · breadth_first_search · grids
Minimum Coins with Unlimited Reuse Premium
dynamic_programming · arrays
Longest Increasing Subsequences: Length and Count Premium
dynamic_programming · binary_search · fenwick_tree
Running Median at Requested Checkpoints Premium
heaps · streaming · order_statistics
LRU Cache with Capacity Changes Premium
hash_maps · linked_lists · simulation
Course Dependencies and Earliest Completion Premium
graphs · topological_sort · heaps · dynamic_programming
Weighted Execution-Window Scheduling Premium
intervals · binary_search · dynamic_programming · scheduling
Minimum Transfer Fees with a Hop Budget Premium
graphs · dynamic_programming · shortest_path
Price-Time Priority Order-Book Matching Premium
heaps · simulation · market_microstructure
Rolling Price Minimum and Maximum Premium
deques · sliding_window · streaming · time_series
Study times are guidance. Efficiency targets describe the intended algorithm, not an automatic Big-O verdict.