The EPI Judge is ready! This screenshot should give you a good idea of what it's about.
You can also view these one minute screencapture videos on YouTube to see how easy it is to get started with the judge: PyCharm, IntelliJ, CLion
EPI Judge consists of the following:
- Stub programs for each problem in our book in Python, Java, and C++
- Test-cases that cover common corner-case and performance bugs
- A framework for running these tests on your implementation on your machine
The installation is super-simple - there's no install! You just download the project, point your IDE/editor to it, and start the code-debug cycle, with instant feedback!
The best interview preparation is a combination of hands-on practice over a representative set of problems with quality explanations.
The best way to get this hands-on practice is by developing, running, and debugging programs in the environment you're most comfortable with, i.e., your own computer and IDE/editor:
- It's a very fast compile-debug cycle,
- you have complete control and visibility, both into the internal state and the test data,
- you can use the features such as autocomplete, autoformat, linting, definiton lookups, etc., and
- you can choose to use version control, to track your own progress, as well as to pull updates.
A big shout-out to Viacheslav Kroilov, for applying his exceptional software engineering skills to make EPI Judge a reality.
| Problem | C++ | Java | Python |
|---|---|---|---|
| Bootcamp: Primitive Types | count_bits.cc | CountBits.java | count_bits.py |
| Computing the parity of a word | parity.cc | Parity.java | parity.py |
| Swap bits | swap_bits.cc | SwapBits.java | swap_bits.py |
| Reverse bits | reverse_bits.cc | ReverseBits.java | reverse_bits.py |
| Find a closest integer with the same weight | closest_int_same_weight.cc | ClosestIntSameWeight.java | closest_int_same_weight.py |
| Compute x * y without arithmetical operators | primitive_multiply.cc | PrimitiveMultiply.java | primitive_multiply.py |
| Compute x/y | primitive_divide.cc | PrimitiveDivide.java | primitive_divide.py |
| Compute x^y | power_x_y.cc | PowerXY.java | power_x_y.py |
| Reverse digits | reverse_digits.cc | ReverseDigits.java | reverse_digits.py |
| Check if a decimal integer is a palindrome | is_number_palindromic.cc | IsNumberPalindromic.java | is_number_palindromic.py |
| Generate uniform random numbers | uniform_random_number.cc | UniformRandomNumber.java | uniform_random_number.py |
| Rectangle intersection | rectangle_intersection.cc | RectangleIntersection.java | rectangle_intersection.py |
| Bootcamp: Arrays | even_odd_array.cc | EvenOddArray.java | even_odd_array.py |
| The Dutch national flag problem | dutch_national_flag.cc | DutchNationalFlag.java | dutch_national_flag.py |
| Increment an arbitrary-precision integer | int_as_array_increment.cc | IntAsArrayIncrement.java | int_as_array_increment.py |
| Multiply two arbitrary-precision integers | int_as_array_multiply.cc | IntAsArrayMultiply.java | int_as_array_multiply.py |
| Advancing through an array | advance_by_offsets.cc | AdvanceByOffsets.java | advance_by_offsets.py |
| Delete duplicates from a sorted array | sorted_array_remove_dups.cc | SortedArrayRemoveDups.java | sorted_array_remove_dups.py |
| Buy and sell a stock once | buy_and_sell_stock.cc | BuyAndSellStock.java | buy_and_sell_stock.py |
| Buy and sell a stock twice | buy_and_sell_stock_twice.cc | BuyAndSellStockTwice.java | buy_and_sell_stock_twice.py |
| Computing an alternation | alternating_array.cc | AlternatingArray.java | alternating_array.py |
| Enumerate all primes to n | prime_sieve.cc | PrimeSieve.java | prime_sieve.py |
| Permute the elements of an array | apply_permutation.cc | ApplyPermutation.java | apply_permutation.py |
| Compute the next permutation | next_permutation.cc | NextPermutation.java | next_permutation.py |
| Sample offline data | offline_sampling.cc | OfflineSampling.java | offline_sampling.py |
| Sample online data | online_sampling.cc | OnlineSampling.java | online_sampling.py |
| Compute a random permutation | random_permutation.cc | RandomPermutation.java | random_permutation.py |
| Compute a random subset | random_subset.cc | RandomSubset.java | random_subset.py |
| Generate nonuniform random numbers | nonuniform_random_number.cc | NonuniformRandomNumber.java | nonuniform_random_number.py |
| The Sudoku checker problem | is_valid_sudoku.cc | IsValidSudoku.java | is_valid_sudoku.py |
| Compute the spiral ordering of a 2D array | spiral_ordering_segments.cc | SpiralOrderingSegments.java | spiral_ordering_segments.py |
| Rotate a 2D array | matrix_rotation.cc | MatrixRotation.java | matrix_rotation.py |
| Compute rows in Pascal's Triangle | pascal_triangle.cc | PascalTriangle.java | pascal_triangle.py |
| Interconvert strings and integers | string_integer_interconversion.cc | StringIntegerInterconversion.java | string_integer_interconversion.py |
| Base conversion | convert_base.cc | ConvertBase.java | convert_base.py |
| Compute the spreadsheet column encoding | spreadsheet_encoding.cc | SpreadsheetEncoding.java | spreadsheet_encoding.py |
| Replace and remove | replace_and_remove.cc | ReplaceAndRemove.java | replace_and_remove.py |
| Test palindromicity | is_string_palindromic_punctuation.cc | IsStringPalindromicPunctuation.java | is_string_palindromic_punctuation.py |
| Reverse all the words in a sentence | reverse_words.cc | ReverseWords.java | reverse_words.py |
| Compute all mnemonics for a phone number | phone_number_mnemonic.cc | PhoneNumberMnemonic.java | phone_number_mnemonic.py |
| The look-and-say problem | look_and_say.cc | LookAndSay.java | look_and_say.py |
| Convert from Roman to decimal | roman_to_integer.cc | RomanToInteger.java | roman_to_integer.py |
| Compute all valid IP addresses | valid_ip_addresses.cc | ValidIpAddresses.java | valid_ip_addresses.py |
| Write a string sinusoidally | snake_string.cc | SnakeString.java | snake_string.py |
| Implement run-length encoding | run_length_compression.cc | RunLengthCompression.java | run_length_compression.py |
| Find the first occurrence of a substring | substring_match.cc | SubstringMatch.java | substring_match.py |
| Bootcamp: Linked Lists | search_in_list.cc | SearchInList.java | search_in_list.py |
| Bootcamp: Linked Lists | insert_in_list.cc | InsertInList.java | insert_in_list.py |
| Bootcamp: Linked Lists | delete_from_list.cc | DeleteFromList.java | delete_from_list.py |
| Merge two sorted lists | sorted_lists_merge.cc | SortedListsMerge.java | sorted_lists_merge.py |
| Reverse a single sublist | reverse_sublist.cc | ReverseSublist.java | reverse_sublist.py |
| Test for cyclicity | is_list_cyclic.cc | IsListCyclic.java | is_list_cyclic.py |
| Test for overlapping lists - lists are cycle-free | do_terminated_lists_overlap.cc | DoTerminatedListsOverlap.java | do_terminated_lists_overlap.py |
| Test for overlapping lists - lists may have cycles | do_lists_overlap.cc | DoListsOverlap.java | do_lists_overlap.py |
| Delete a node from a singly linked list | delete_node_from_list.cc | DeleteNodeFromList.java | delete_node_from_list.py |
| Remove the kth last element from a list | delete_kth_last_from_list.cc | DeleteKthLastFromList.java | delete_kth_last_from_list.py |
| Remove duplicates from a sorted list | remove_duplicates_from_sorted_list.cc | RemoveDuplicatesFromSortedList.java | remove_duplicates_from_sorted_list.py |
| Implement cyclic right shift for singly linked lists | list_cyclic_right_shift.cc | ListCyclicRightShift.java | list_cyclic_right_shift.py |
| Implement even-odd merge | even_odd_list_merge.cc | EvenOddListMerge.java | even_odd_list_merge.py |
| Test whether a singly linked list is palindromic | is_list_palindromic.cc | IsListPalindromic.java | is_list_palindromic.py |
| Implement list pivoting | pivot_list.cc | PivotList.java | pivot_list.py |
| Add list-based integers | int_as_list_add.cc | IntAsListAdd.java | int_as_list_add.py |
| Implement a stack with max API | stack_with_max.cc | StackWithMax.java | stack_with_max.py |
| Evaluate RPN expressions | evaluate_rpn.cc | EvaluateRpn.java | evaluate_rpn.py |
| Test a string over ''{,},(,),[,]'' for well-formedness | is_valid_parenthesization.cc | IsValidParenthesization.java | is_valid_parenthesization.py |
| Normalize pathnames | directory_path_normalization.cc | DirectoryPathNormalization.java | directory_path_normalization.py |
| Compute buildings with a sunset view | sunset_view.cc | SunsetView.java | sunset_view.py |
| Compute binary tree nodes in order of increasing depth | tree_level_order.cc | TreeLevelOrder.java | tree_level_order.py |
| Implement a circular queue | circular_queue.cc | CircularQueue.java | circular_queue.py |
| Implement a queue using stacks | queue_from_stacks.cc | QueueFromStacks.java | queue_from_stacks.py |
| Implement a queue with max API | queue_with_max.cc | QueueWithMax.java | queue_with_max.py |
| Test if a binary tree is height-balanced | is_tree_balanced.cc | IsTreeBalanced.java | is_tree_balanced.py |
| Test if a binary tree is symmetric | is_tree_symmetric.cc | IsTreeSymmetric.java | is_tree_symmetric.py |
| Compute the lowest common ancestor in a binary tree | lowest_common_ancestor.cc | LowestCommonAncestor.java | lowest_common_ancestor.py |
| Compute the LCA when nodes have parent pointers | lowest_common_ancestor_with_parent.cc | LowestCommonAncestorWithParent.java | lowest_common_ancestor_with_parent.py |
| Sum the root-to-leaf paths in a binary tree | sum_root_to_leaf.cc | SumRootToLeaf.java | sum_root_to_leaf.py |
| Find a root to leaf path with specified sum | path_sum.cc | PathSum.java | path_sum.py |
| Implement an inorder traversal without recursion | tree_inorder.cc | TreeInorder.java | tree_inorder.py |
| Implement a preorder traversal without recursion | tree_preorder.cc | TreePreorder.java | tree_preorder.py |
| Compute the kth node in an inorder traversal | kth_node_in_tree.cc | KthNodeInTree.java | kth_node_in_tree.py |
| Compute the successor | successor_in_tree.cc | SuccessorInTree.java | successor_in_tree.py |
| Implement an inorder traversal with O(1) space | tree_with_parent_inorder.cc | TreeWithParentInorder.java | tree_with_parent_inorder.py |
| Reconstruct a binary tree from traversal data | tree_from_preorder_inorder.cc | TreeFromPreorderInorder.java | tree_from_preorder_inorder.py |
| Reconstruct a binary tree from a preorder traversal with markers | tree_from_preorder_with_null.cc | TreeFromPreorderWithNull.java | tree_from_preorder_with_null.py |
| Form a linked list from the leaves of a binary tree | tree_connect_leaves.cc | TreeConnectLeaves.java | tree_connect_leaves.py |
| Compute the exterior of a binary tree | tree_exterior.cc | TreeExterior.java | tree_exterior.py |
| Compute the right sibling tree | tree_right_sibling.cc | TreeRightSibling.java | tree_right_sibling.py |
| Merge sorted files | sorted_arrays_merge.cc | SortedArraysMerge.java | sorted_arrays_merge.py |
| Sort an increasing-decreasing array | sort_increasing_decreasing_array.cc | SortIncreasingDecreasingArray.java | sort_increasing_decreasing_array.py |
| Sort an almost-sorted array | sort_almost_sorted_array.cc | SortAlmostSortedArray.java | sort_almost_sorted_array.py |
| Compute the k closest stars | k_closest_stars.cc | KClosestStars.java | k_closest_stars.py |
| Compute the median of online data | online_median.cc | OnlineMedian.java | online_median.py |
| Compute the k largest elements in a max-heap | k_largest_in_heap.cc | KLargestInHeap.java | k_largest_in_heap.py |
| Search a sorted array for first occurrence of k | search_first_key.cc | SearchFirstKey.java | search_first_key.py |
| Search a sorted array for entry equal to its index | search_entry_equal_to_index.cc | SearchEntryEqualToIndex.java | search_entry_equal_to_index.py |
| Search a cyclically sorted array | search_shifted_sorted_array.cc | SearchShiftedSortedArray.java | search_shifted_sorted_array.py |
| Compute the integer square root | int_square_root.cc | IntSquareRoot.java | int_square_root.py |
| Compute the real square root | real_square_root.cc | RealSquareRoot.java | real_square_root.py |
| Search in a 2D sorted array | search_row_col_sorted_matrix.cc | SearchRowColSortedMatrix.java | search_row_col_sorted_matrix.py |
| Find the min and max simultaneously | search_for_min_max_in_array.cc | SearchForMinMaxInArray.java | search_for_min_max_in_array.py |
| Find the kth largest element | kth_largest_in_array.cc | KthLargestInArray.java | kth_largest_in_array.py |
| Find the missing IP address | absent_value_array.cc | AbsentValueArray.java | absent_value_array.py |
| Find the duplicate and missing elements | search_for_missing_element.cc | SearchForMissingElement.java | search_for_missing_element.py |
| Bootcamp: Hash Tables | anagrams.cc | Anagrams.java | anagrams.py |
| Test for palindromic permutations | is_string_permutable_to_palindrome.cc | IsStringPermutableToPalindrome.java | is_string_permutable_to_palindrome.py |
| Is an anonymous letter constructible? | is_anonymous_letter_constructible.cc | IsAnonymousLetterConstructible.java | is_anonymous_letter_constructible.py |
| Implement an ISBN cache | lru_cache.cc | LRUCache.java | lru_cache.py |
| Compute the LCA, optimizing for close ancestors | lowest_common_ancestor_close_ancestor.cc | LowestCommonAncestorCloseAncestor.java | lowest_common_ancestor_close_ancestor.py |
| Find the nearest repeated entries in an array | nearest_repeated_entries.cc | NearestRepeatedEntries.java | nearest_repeated_entries.py |
| Find the smallest subarray covering all values | smallest_subarray_covering_set.cc | SmallestSubarrayCoveringSet.java | smallest_subarray_covering_set.py |
| Find smallest subarray sequentially covering all values | smallest_subarray_covering_all_values.cc | SmallestSubarrayCoveringAllValues.java | smallest_subarray_covering_all_values.py |
| Find the longest subarray with distinct entries | longest_subarray_with_distinct_values.cc | LongestSubarrayWithDistinctValues.java | longest_subarray_with_distinct_values.py |
| Find the length of a longest contained interval | longest_contained_interval.cc | LongestContainedInterval.java | longest_contained_interval.py |
| Compute all string decompositions | string_decompositions_into_dictionary_words.cc | StringDecompositionsIntoDictionaryWords.java | string_decompositions_into_dictionary_words.py |
| Test the Collatz conjecture | collatz_checker.cc | CollatzChecker.java | collatz_checker.py |
| Compute the intersection of two sorted arrays | intersect_sorted_arrays.cc | IntersectSortedArrays.java | intersect_sorted_arrays.py |
| Remove first-name duplicates | remove_duplicates.cc | RemoveDuplicates.java | remove_duplicates.py |
| Smallest nonconstructible value | smallest_nonconstructible_value.cc | SmallestNonconstructibleValue.java | smallest_nonconstructible_value.py |
| Render a calendar | calendar_rendering.cc | CalendarRendering.java | calendar_rendering.py |
| Merging intervals | interval_add.cc | IntervalAdd.java | interval_add.py |
| Compute the union of intervals | intervals_union.cc | IntervalsUnion.java | intervals_union.py |
| Partitioning and sorting an array with many repeated entries | group_equal_entries.cc | GroupEqualEntries.java | group_equal_entries.py |
| Team photo day - 1 | is_array_dominated.cc | IsArrayDominated.java | is_array_dominated.py |
| Implement a fast sorting algorithm for lists | sort_list.cc | SortList.java | sort_list.py |
| Compute a salary threshold | find_salary_threshold.cc | FindSalaryThreshold.java | find_salary_threshold.py |
| Test if a binary tree satisfies the BST property | is_tree_a_bst.cc | IsTreeABst.java | is_tree_a_bst.py |
| Find the first key greater than a given value in a BST | search_first_greater_value_in_bst.cc | SearchFirstGreaterValueInBst.java | search_first_greater_value_in_bst.py |
| Find the k largest elements in a BST | k_largest_values_in_bst.cc | KLargestValuesInBst.java | k_largest_values_in_bst.py |
| Compute the LCA in a BST | lowest_common_ancestor_in_bst.cc | LowestCommonAncestorInBst.java | lowest_common_ancestor_in_bst.py |
| Reconstruct a BST from traversal data | bst_from_preorder.cc | BstFromPreorder.java | bst_from_preorder.py |
| Find the closest entries in three sorted arrays | minimum_distance_3_sorted_arrays.cc | MinimumDistance3SortedArrays.java | minimum_distance_3_sorted_arrays.py |
| Build a minimum height BST from a sorted array | bst_from_sorted_array.cc | BstFromSortedArray.java | bst_from_sorted_array.py |
| Test if three BST nodes are totally ordered | descendant_and_ancestor_in_bst.cc | DescendantAndAncestorInBst.java | descendant_and_ancestor_in_bst.py |
| Add credits | adding_credits.cc | AddingCredits.java | adding_credits.py |
| The Towers of Hanoi problem | hanoi.cc | Hanoi.java | hanoi.py |
| Generate all nonattacking placements of n-Queens | n_queens.cc | NQueens.java | n_queens.py |
| Generate permutations | permutations.cc | Permutations.java | permutations.py |
| Generate the power set | power_set.cc | PowerSet.java | power_set.py |
| Generate all subsets of size k | combinations.cc | Combinations.java | combinations.py |
| Generate strings of matched parens | enumerate_balanced_parentheses.cc | EnumerateBalancedParentheses.java | enumerate_balanced_parentheses.py |
| Generate palindromic decompositions | enumerate_palindromic_decompositions.cc | EnumeratePalindromicDecompositions.java | enumerate_palindromic_decompositions.py |
| Generate binary trees | enumerate_trees.cc | EnumerateTrees.java | enumerate_trees.py |
| Implement a Sudoku solver | sudoku_solve.cc | SudokuSolve.java | sudoku_solve.py |
| Compute a Gray code | gray_code.cc | GrayCode.java | gray_code.py |
| Count the number of score combinations | number_of_score_combinations.cc | NumberOfScoreCombinations.java | number_of_score_combinations.py |
| Compute the Levenshtein distance | levenshtein_distance.cc | LevenshteinDistance.java | levenshtein_distance.py |
| Count the number of ways to traverse a 2D array | number_of_traversals_matrix.cc | NumberOfTraversalsMatrix.java | number_of_traversals_matrix.py |
| Compute the binomial coefficients | binomial_coefficients.cc | BinomialCoefficients.java | binomial_coefficients.py |
| Search for a sequence in a 2D array | is_string_in_matrix.cc | IsStringInMatrix.java | is_string_in_matrix.py |
| The knapsack problem | knapsack.cc | Knapsack.java | knapsack.py |
| The bedbathandbeyond.com problem | is_string_decomposable_into_words.cc | IsStringDecomposableIntoWords.java | is_string_decomposable_into_words.py |
| Find the minimum weight path in a triangle | minimum_weight_path_in_a_triangle.cc | MinimumWeightPathInATriangle.java | minimum_weight_path_in_a_triangle.py |
| Pick up coins for maximum gain | picking_up_coins.cc | PickingUpCoins.java | picking_up_coins.py |
| Count the number of moves to climb stairs | number_of_traversals_staircase.cc | NumberOfTraversalsStaircase.java | number_of_traversals_staircase.py |
| The pretty printing problem | pretty_printing.cc | PrettyPrinting.java | pretty_printing.py |
| Find the longest nondecreasing subsequence | longest_nondecreasing_subsequence.cc | LongestNondecreasingSubsequence.java | longest_nondecreasing_subsequence.py |
| Compute an optimum assignment of tasks | task_pairing.cc | TaskPairing.java | task_pairing.py |
| Schedule to minimize waiting time | minimum_waiting_time.cc | MinimumWaitingTime.java | minimum_waiting_time.py |
| The interval covering problem | minimum_points_covering_intervals.cc | MinimumPointsCoveringIntervals.java | minimum_points_covering_intervals.py |
| The interval covering problem | two_sum.cc | TwoSum.java | two_sum.py |
| The 3-sum problem | three_sum.cc | ThreeSum.java | three_sum.py |
| Find the majority element | majority_element.cc | MajorityElement.java | majority_element.py |
| The gasup problem | refueling_schedule.cc | RefuelingSchedule.java | refueling_schedule.py |
| Compute the largest rectangle under the skyline | largest_rectangle_under_skyline.cc | LargestRectangleUnderSkyline.java | largest_rectangle_under_skyline.py |
| Search a maze | search_maze.cc | SearchMaze.java | search_maze.py |
| Compute enclosed regions | matrix_enclosed_regions.cc | MatrixEnclosedRegions.java | matrix_enclosed_regions.py |
| Deadlock detection | deadlock_detection.cc | DeadlockDetection.java | deadlock_detection.py |
| Clone a graph | graph_clone.cc | GraphClone.java | graph_clone.py |
| Making wired connections | is_circuit_wirable.cc | IsCircuitWirable.java | is_circuit_wirable.py |
| Transform one string to another | string_transformability.cc | StringTransformability.java | string_transformability.py |
| Team photo day - 2 | max_teams_in_photograph.cc | MaxTeamsInPhotograph.java | max_teams_in_photograph.py |
| Compute the greatest common divisor | gcd.cc | Gcd.java | gcd.py |
| Find the first missing positive entry | first_missing_positive_entry.cc | FirstMissingPositiveEntry.java | first_missing_positive_entry.py |
| Buy and sell a stock k times | buy_and_sell_stock_k_times.cc | BuyAndSellStockKTimes.java | buy_and_sell_stock_k_times.py |
| Compute the maximum product of all entries but one | max_product_all_but_one.cc | MaxProductAllButOne.java | max_product_all_but_one.py |
| Compute the longest contiguous increasing subarray | longest_increasing_subarray.cc | LongestIncreasingSubarray.java | longest_increasing_subarray.py |
| Rotate an array | rotate_array.cc | RotateArray.java | rotate_array.py |
| Identify positions attacked by rooks | rook_attack.cc | RookAttack.java | rook_attack.py |
| Justify text | left_right_justify_text.cc | LeftRightJustifyText.java | left_right_justify_text.py |
| Implement list zipping | zip_list.cc | ZipList.java | zip_list.py |
| Copy a postings list | copy_posting_list.cc | CopyPostingList.java | copy_posting_list.py |
| Compute the longest substring with matching parens | longest_substring_with_matching_parentheses.cc | LongestSubstringWithMatchingParentheses.java | longest_substring_with_matching_parentheses.py |
| Compute the maximum of a sliding window | max_of_sliding_window.cc | MaxOfSlidingWindow.java | max_of_sliding_window.py |
| Implement a postorder traversal without recursion | tree_postorder.cc | TreePostorder.java | tree_postorder.py |
| Compute fair bonuses | bonus.cc | Bonus.java | bonus.py |
| Search a sorted array of unknown length | search_unknown_length_array.cc | SearchUnknownLengthArray.java | search_unknown_length_array.py |
| Search in two sorted arrays | kth_largest_element_in_two_sorted_arrays.cc | KthLargestElementInTwoSortedArrays.java | kth_largest_element_in_two_sorted_arrays.py |
| Find an element that appears only once | element_appearing_once.cc | ElementAppearingOnce.java | element_appearing_once.py |
| Find the line through the most points | line_though_most_points.cc | LineThoughMostPoints.java | line_though_most_points.py |
| Convert a sorted doubly linked list into a BST | sorted_list_to_bst.cc | SortedListToBst.java | sorted_list_to_bst.py |
| Convert a BST to a sorted doubly linked list | bst_to_sorted_list.cc | BstToSortedList.java | bst_to_sorted_list.py |
| Merge two BSTs | bst_merge.cc | BstMerge.java | bst_merge.py |
| Implement regular expression matching | regular_expression.cc | RegularExpression.java | regular_expression.py |
| Synthesize an expression | insert_operators_in_string.cc | InsertOperatorsInString.java | insert_operators_in_string.py |
| Count inversions | count_inversions.cc | CountInversions.java | count_inversions.py |
| Draw the skyline | drawing_skyline.cc | DrawingSkyline.java | drawing_skyline.py |
| Measure with defective jugs | defective_jugs.cc | DefectiveJugs.java | defective_jugs.py |
| Compute the maximum subarray sum in a circular array | maximum_subarray_in_circular_array.cc | MaximumSubarrayInCircularArray.java | maximum_subarray_in_circular_array.py |
| Determine the critical height | max_safe_height.cc | MaxSafeHeight.java | max_safe_height.py |
| Find the maximum 2D subarray | max_submatrix.cc | MaxSubmatrix.java | max_submatrix.py |
| Find the maximum 2D subarray | max_square_submatrix.cc | MaxSquareSubmatrix.java | max_square_submatrix.py |
| Implement Huffman coding | huffman_coding.cc | HuffmanCoding.java | huffman_coding.py |
| Trapping water | max_water_trappable.cc | MaxWaterTrappable.java | max_water_trappable.py |
| The heavy hitter problem | search_frequent_items.cc | SearchFrequentItems.java | search_frequent_items.py |
| Find the longest subarray whose sum <= k | longest_subarray_with_sum_constraint.cc | LongestSubarrayWithSumConstraint.java | longest_subarray_with_sum_constraint.py |
| Road network | road_network.cc | RoadNetwork.java | road_network.py |
| Test if arbitrage is possible | arbitrage.cc | Arbitrage.java | arbitrage.py |