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EPI Judge


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


Here's how to download the judge:

$ git clone https://github.com/adnanaziz/EPIJudge.git

If you do not have git, here's a good tutorial on installing git itself.

Running the judge using IDEs

Check out these one minute videos to see how easy it is to get started with the judge.


PyCharm, Eclipse, NetBeans


IntelliJ IDEA, Eclipse


CLion, Visual Studio 2017

Running the judge from the command line


$ python3 <program_name>.py


Use the Makefile.

Compile and run a specific program:

$ make <program_name> 


$ make Anagrams

Compile and run the last program that you edited:

$ make


You can manually compile and run all programs by directly invoking GCC and Clang.

$ g++ -pthread -std=c++14 -O3 -o anagrams anagrams.cc

You can also use the provided Makefile: make <program_name>. You can also use CMake with the provided CMakeLists.txt file.

$ make 

The default Makefile target is the last edited file.

$ make anagrams


  • How can I contact the authors?

Please feel free to send us questions and feedback - adnan.aziz@gmail.com and tsung.hsien.lee@gmail.com

  • Help, my EPIJudge is not working, what should I do?

If you do have issues, e.g., with install or with buggy tests, feel free to reach out to us via email. Please be as detailed as you can: the ideal is if you can upload a screencast video of the issue to youtube; failing that, please upload screenshots. The more detailed the description of the problem and your environment (OS, language version, IDE and version), the easier it’ll be for us to help you.

  • I'm new to programming, and don't have any kind of development environment, what should I do?

The IntelliJ Integrated Development environments described above are best-in-class, and have free versions that will work fine for the EPI Judge. They do not include the compilers. You can get the Java development environment from Oracle, and the Python development environment from Python.org. For C++, you have multiple options. The simplest is to install VisualStudio, which includes both the IDE and the compiler. Google is a good resource for installation help.

  • What compilers are supported for judge?

    • C++
      • Linux
        • GCC 5.4.1
        • Clang 4.0
      • OS X
        • Apple LLVM Clang 9.0.0
      • Windows
        • Visual Studio 2017 15.7.0 Preview 6
          • Release version of VS2017 contains a bug that makes it impossible to compile judge programs
        • MinGW GCC 5.4.0
        • LXSS (Windows Subsystem for Linux) GCC 5.4.0
    • Java
      • Java 9
    • Python
      • Python 3.6
  • What compilers are supported for solutions?

    • C++
      • Linux
        • GCC 7.0.0
        • Clang 5.0
      • OS X
        • Apple LLVM Clang 9.0.0
      • Windows
        • Visual Studio 2017 15.7.0 Preview 6
          • Release version of VS2017 contains a bug that makes it impossible to compile judge programs
        • MinGW GCC 7.2.0
        • LXSS (Windows Subsystem for Linux) GCC 7.2.0
      • Java
        • Java 9
      • Python
        • Python 3.6

Let us know if you managed to compile with an older version.

  • What does the UI look like?

Take a look at this screenshot.

  • How can I understand the test framework better?

The judge harness is fairly complex (but does not use nonstandard language features or libraries). You are welcome to study it, but we’d advise you against making changes to it (since it will lead to nasty merge conflicts when you update).

  • How do I import the C++ project?

If you want to import the project into your favourite IDE, you probably need to create IDE project with CMake (no need to do it for CLion, it supports CMake out-of-the-box).

Here is an example recipe for generationg Visual Studio project (list of all CMake supported IDEs). After installing CMake, open your terminal, go to epi_judge_cpp folder and run following commands:

mkdir vs
cd vs
cmake -G "Visual Studio 15 2017" ..

Then just open epi_judge_cpp/vs/epi_judge_cpp.sln solution with Visual Studio and it will load all EPI programs.

Problem to Program Mapping

(You may have to scroll to the right to view the Python column.)

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
Merge two sorted arrays two_sorted_arrays_merge.cc TwoSortedArraysMerge.java two_sorted_arrays_merge.py
Computing the h-index h_index.cc HIndex.java h_index.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
Enumerate numbers of the form a + b sqrt(2) a_b_sqrt2.cc ABSqrt2.java a_b_sqrt2.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
The range lookup problem range_lookup_in_bst.cc RangeLookupInBst.java range_lookup_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
Bootcamp: Dynamic Programming fibonacci.cc Fibonacci.java fibonacci.py
Bootcamp: Dynamic Programming max_sum_subarray.cc MaxSumSubarray.java max_sum_subarray.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 maximum water trapped by a pair of vertical lines max_trapped_water.cc MaxTrappedWater.java max_trapped_water.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
Paint a Boolean matrix matrix_connected_regions.cc MatrixConnectedRegions.java matrix_connected_regions.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 the kth largest element - large n, small k kth_largest_element_in_long_array.cc KthLargestElementInLongArray.java kth_largest_element_in_long_array.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_through_most_points.cc LineThroughMostPoints.java line_through_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


A big shout-out to the hundreds of users who tried out the release over the past couple of months. As always, we never fail to be impressed by the enthusiasm and commitment our readers have; it has served to bring out the best in us. We all thank Viacheslav Kroilov, for applying his exceptional software engineering skills to make EPI Judge a reality.