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    String ChangesNot Completed

    Solutions: 13 | View user solutions | Added 08/15/18

    Group TotalsNot Completed

    Solutions: 139 | View user solutions | Added 04/30/18

    Moving MedianNot Completed

    Solutions: 170 | View user solutions | Added 11/30/17

    Free Challenges

    Longest WordNot Completed

    Solutions: 72850 | Step-by-step solution | Challenge discussion

    First FactorialNot Completed

    Solutions: 91400 | Step-by-step solution | Challenge discussion

    First ReverseNot Completed

    Solutions: 113369 | Step-by-step solution | Challenge discussion

    Letter ChangesNot Completed

    Solutions: 69524 | Step-by-step solution | Challenge discussion

    Simple AddingNot Completed

    Solutions: 56800 | Step-by-step solution | Challenge discussion

    Letter CapitalizeNot Completed

    Solutions: 48331 | Step-by-step solution | Challenge discussion

    Simple SymbolsNot Completed

    Solutions: 41090 | Step-by-step solution | Challenge discussion

    Check NumsNot Completed

    Solutions: 41583 | Step-by-step solution | Challenge discussion

    Time ConvertNot Completed

    Solutions: 31634 | Step-by-step solution | Challenge discussion

    Alphabet SoupNot Completed

    Solutions: 29179 | Step-by-step solution | Challenge discussion

    Kaprekars ConstantNot Completed

    Solutions: 4333 | View all user solutions | Challenge discussion

    Chessboard TravelingNot Completed

    Solutions: 1844 | View all user solutions | Challenge discussion

    Maximal SquareNot Completed

    Solutions: 1178 | View all user solutions | Challenge discussion

    Pentagonal NumberNot Completed

    Solutions: 1274 | View all user solutions | Challenge discussion

    Correct PathNot Completed

    Solutions: 1469 | View all user solutions | Challenge discussion

    Scale BalancingNot Completed

    Solutions: 2028 | View all user solutions | Challenge discussion

    Vowel SquareNot Completed

    Solutions: 1317 | View all user solutions | Challenge discussion

    Eight QueensNot Completed

    Solutions: 963 | View all user solutions | Challenge discussion

    Closest Enemy IINot Completed

    Solutions: 1152 | View all user solutions | Challenge discussion

    Questions MarksNot Completed

    Solutions: 3308 | View all user solutions | Challenge discussion

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    Easy Difficulty

    First ReverseNot Completed

    Solutions: 113369 | Step-by-step solution | Challenge discussion

    First FactorialNot Completed

    Solutions: 91400 | Step-by-step solution | Challenge discussion

    Longest WordNot Completed

    Solutions: 72850 | Step-by-step solution | Challenge discussion

    Letter ChangesNot Completed

    Solutions: 69524 | Step-by-step solution | Challenge discussion

    Simple AddingNot Completed

    Solutions: 56800 | Step-by-step solution | Challenge discussion

    Letter CapitalizeNot Completed

    Solutions: 48331 | Step-by-step solution | Challenge discussion

    Simple SymbolsNot Completed

    Solutions: 41090 | Step-by-step solution | Challenge discussion

    Check NumsNot Completed

    Solutions: 41583 | Step-by-step solution | Challenge discussion

    Time ConvertNot Completed

    Solutions: 31634 | Step-by-step solution | Challenge discussion

    Alphabet SoupNot Completed

    Solutions: 29179 | Step-by-step solution | Challenge discussion

    AB CheckNot Completed

    Solutions: 16904 | Step-by-step solution | Challenge discussion

    Vowel CountNot Completed

    Solutions: 15544 | Step-by-step solution | Challenge discussion

    Word CountNot Completed

    Solutions: 14686 | Step-by-step solution | Challenge discussion

    Ex OhNot Completed

    Solutions: 14375 | Step-by-step solution | Challenge discussion

    PalindromeNot Completed

    Solutions: 16746 | Step-by-step solution | Challenge discussion

    Arith GeoNot Completed

    Solutions: 13340 | Step-by-step solution | Challenge discussion

    Array Addition INot Completed

    Solutions: 8533 | Step-by-step solution | Challenge discussion

    Letter Count INot Completed

    Solutions: 7838 | Step-by-step solution | Challenge discussion

    Second GreatLowNot Completed

    Solutions: 12982 | Step-by-step solution | Challenge discussion

    Division StringifiedNot Completed

    Solutions: 9754 | Step-by-step solution | Challenge discussion

    Counting Minutes INot Completed

    Solutions: 5780 | Step-by-step solution | Challenge discussion

    Mean ModeNot Completed

    Solutions: 7560 | Step-by-step solution | Challenge discussion

    Dash InsertNot Completed

    Solutions: 8571 | Step-by-step solution | Challenge discussion

    Swap CaseNot Completed

    Solutions: 8120 | Step-by-step solution | Challenge discussion

    Number AdditionNot Completed

    Solutions: 7991 | Step-by-step solution | Challenge discussion

    Third GreatestNot Completed

    Solutions: 7396 | Step-by-step solution | Challenge discussion

    Powers of TwoNot Completed

    Solutions: 8277 | Step-by-step solution | Challenge discussion

    Additive PersistenceNot Completed

    Solutions: 5894 | Step-by-step solution | Challenge discussion

    Multiplicative PersistenceNot Completed

    Solutions: 4543 | Step-by-step solution | Challenge discussion

    Off Line MinimumNot Completed

    Solutions: 6129 | Step-by-step solution | Challenge discussion

    Changing SequenceNot Completed

    Solutions: 2528 | Step-by-step solution | Challenge discussion

    Overlapping RangesNot Completed

    Solutions: 2529 | Step-by-step solution | Challenge discussion

    SuperincreasingNot Completed

    Solutions: 2567 | Step-by-step solution | Challenge discussion

    Hamming DistanceNot Completed

    Solutions: 1760 | Step-by-step solution | Challenge discussion

    Rectangle AreaNot Completed

    Solutions: 2142 | Step-by-step solution | Challenge discussion

    Bitwise OneNot Completed

    Solutions: 1736 | Step-by-step solution | Challenge discussion

    Other ProductsNot Completed

    Solutions: 1775 | Step-by-step solution | Challenge discussion

    Wave SortingNot Completed

    Solutions: 1238 | Step-by-step solution | Challenge discussion

    Array MatchingNot Completed

    Solutions: 1520 | Step-by-step solution | Challenge discussion

    Binary ReversalNot Completed

    Solutions: 1259 | Step-by-step solution | Challenge discussion

    Longest Increasing SequenceNot Completed

    Solutions: 1211 | Step-by-step solution | Challenge discussion

    Even PairsNot Completed

    Solutions: 1156 | Step-by-step solution | Challenge discussion

    Next PalindromeNot Completed

    Solutions: 1006 | Step-by-step solution | Challenge discussion

    Largest PairNot Completed

    Solutions: 1340 | Step-by-step solution | Challenge discussion

    Nonrepeating CharacterNot Completed

    Solutions: 995 | Step-by-step solution | Challenge discussion

    Two SumNot Completed

    Solutions: 1819 | Step-by-step solution | Challenge discussion

    Bitwise TwoNot Completed

    Solutions: 717 | Step-by-step solution | Challenge discussion

    Power Set CountNot Completed

    Solutions: 1051 | Step-by-step solution | Challenge discussion

    Product DigitsNot Completed

    Solutions: 1320 | Step-by-step solution | Challenge discussion

    Palindrome CreatorNot Completed

    Solutions: 1084 | Step-by-step solution | Challenge discussion

    Basic Roman NumeralsNot Completed

    Solutions: 730 | Step-by-step solution | Challenge discussion

    Food DistributionNot Completed

    Solutions: 621 | Step-by-step solution | Challenge discussion

    Three SumNot Completed

    Solutions: 743 | Step-by-step solution | Challenge discussion

    Correct PathNot Completed

    Solutions: 1469 | Step-by-step solution | Challenge discussion

    Scale BalancingNot Completed

    Solutions: 2028 | Step-by-step solution | Challenge discussion

    Three NumbersNot Completed

    Solutions: 698 | Step-by-step solution | Challenge discussion

    Alphabet SearchingNot Completed

    Solutions: 597 | Step-by-step solution | Challenge discussion

    Time DifferenceNot Completed

    Solutions: 388 | Step-by-step solution | Challenge discussion

    Triangle RowNot Completed

    Solutions: 376 | Step-by-step solution | Challenge discussion

    Vowel SquareNot Completed

    Solutions: 1317 | Step-by-step solution | Challenge discussion

    Closest EnemyNot Completed

    Solutions: 565 | Step-by-step solution | Challenge discussion

    Closest Enemy IINot Completed

    Solutions: 1152 | Step-by-step solution | Challenge discussion

    Number StreamNot Completed

    Solutions: 382 | Step-by-step solution | Challenge discussion

    Largest FourNot Completed

    Solutions: 554 | Step-by-step solution | Challenge discussion

    Distinct CharactersNot Completed

    Solutions: 400 | Step-by-step solution | Challenge discussion

    Questions MarksNot Completed

    Solutions: 3308 | Step-by-step solution | Challenge discussion

    Camel CaseNot Completed

    Solutions: 468 | Step-by-step solution | Challenge discussion

    ASCII ConversionNot Completed

    Solutions: 317 | Step-by-step solution | Challenge discussion

    Simple EvensNot Completed

    Solutions: 436 | Step-by-step solution | Challenge discussion

    Snake CaseNot Completed

    Solutions: 382 | Step-by-step solution | Challenge discussion

    Sum MultiplierNot Completed

    Solutions: 477 | Step-by-step solution | Challenge discussion

    String MergeNot Completed

    Solutions: 452 | Step-by-step solution | Challenge discussion

    One DecrementedNot Completed

    Solutions: 423 | Step-by-step solution | Challenge discussion

    Element MergerNot Completed

    Solutions: 453 | Step-by-step solution | Challenge discussion

    GCFNot Completed

    Solutions: 424 | Step-by-step solution | Challenge discussion

    Serial NumberNot Completed

    Solutions: 585 | Step-by-step solution | Challenge discussion

    String PeriodsNot Completed

    Solutions: 497 | Step-by-step solution | Challenge discussion

    Palindrome SwapperNot Completed

    Solutions: 296 | Step-by-step solution | Challenge discussion

    Remove BracketsNot Completed

    Solutions: 432 | Step-by-step solution | Challenge discussion

    Command LineNot Completed

    Solutions: 195 | Step-by-step solution | Challenge discussion

    Star RatingNot Completed

    Solutions: 395 | Step-by-step solution | Challenge discussion

    Moving MedianNot Completed

    Solutions: 170 | Step-by-step solution | Challenge discussion

    Group TotalsNot Completed

    Solutions: 139 | Step-by-step solution | Challenge discussion

    String ChangesNot Completed

    Solutions: 13 | Step-by-step solution | Challenge discussion

    Medium Difficulty

    Prime TimeNot Completed

    Solutions: 12026 | Step-by-step solution | Challenge discussion

    Run Length Not Completed

    Solutions: 8564 | Step-by-step solution | Challenge discussion

    Prime MoverNot Completed

    Solutions: 7438 | Step-by-step solution | Challenge discussion

    Palindrome TwoNot Completed

    Solutions: 7120 | Step-by-step solution | Challenge discussion

    DivisionNot Completed

    Solutions: 6629 | Step-by-step solution | Challenge discussion

    String ScrambleNot Completed

    Solutions: 7258 | Step-by-step solution | Challenge discussion

    Arith Geo IINot Completed

    Solutions: 4987 | Step-by-step solution | Challenge discussion

    Array AdditionNot Completed

    Solutions: 4397 | Step-by-step solution | Challenge discussion

    Binary ConverterNot Completed

    Solutions: 4514 | Step-by-step solution | Challenge discussion

    Letter CountNot Completed

    Solutions: 4475 | Step-by-step solution | Challenge discussion

    Caesar CipherNot Completed

    Solutions: 5135 | Step-by-step solution | Challenge discussion

    Simple ModeNot Completed

    Solutions: 4998 | Step-by-step solution | Challenge discussion

    ConsecutiveNot Completed

    Solutions: 4106 | Step-by-step solution | Challenge discussion

    Formatted DivisionNot Completed

    Solutions: 3785 | Step-by-step solution | Challenge discussion

    Counting MinutesNot Completed

    Solutions: 2785 | View all user solutions | Challenge discussion

    Permutation StepNot Completed

    Solutions: 3309 | View all user solutions | Challenge discussion

    Prime CheckerNot Completed

    Solutions: 2541 | View all user solutions | Challenge discussion

    Dash Insert IINot Completed

    Solutions: 4922 | View all user solutions | Challenge discussion

    Swap IINot Completed

    Solutions: 2732 | View all user solutions | Challenge discussion

    Number SearchNot Completed

    Solutions: 3352 | View all user solutions | Challenge discussion

    Triple DoubleNot Completed

    Solutions: 3121 | View all user solutions | Challenge discussion

    Bracket MatcherNot Completed

    Solutions: 2838 | View all user solutions | Challenge discussion

    String ReductionNot Completed

    Solutions: 2350 | View all user solutions | Challenge discussion

    ThreeFive MultiplesNot Completed

    Solutions: 2831 | View all user solutions | Challenge discussion

    Binary Search Tree LCANot Completed

    Solutions: 277 | View all user solutions | Challenge discussion

    Coin DeterminerNot Completed

    Solutions: 2303 | View all user solutions | Challenge discussion

    Fibonacci CheckerNot Completed

    Solutions: 2648 | View all user solutions | Challenge discussion

    Multiple BracketsNot Completed

    Solutions: 2351 | View all user solutions | Challenge discussion

    Most Free TimeNot Completed

    Solutions: 1413 | View all user solutions | Challenge discussion

    Overlapping RectanglesNot Completed

    Solutions: 1618 | View all user solutions | Challenge discussion

    Look Say SequenceNot Completed

    Solutions: 1472 | View all user solutions | Challenge discussion

    Distinct ListNot Completed

    Solutions: 2400 | View all user solutions | Challenge discussion

    Number EncodingNot Completed

    Solutions: 1490 | View all user solutions | Challenge discussion

    Stock PickerNot Completed

    Solutions: 739 | View all user solutions | Challenge discussion

    Max SubarrayNot Completed

    Solutions: 656 | View all user solutions | Challenge discussion

    Missing DigitNot Completed

    Solutions: 449 | View all user solutions | Challenge discussion

    K Unique CharactersNot Completed

    Solutions: 446 | View all user solutions | Challenge discussion

    Bitmap HolesNot Completed

    Solutions: 328 | View all user solutions | Challenge discussion

    Symmetric TreeNot Completed

    Solutions: 285 | View all user solutions | Challenge discussion

    Binary Tree LCANot Completed

    Solutions: 152 | View all user solutions | Challenge discussion

    LRU CacheNot Completed

    Solutions: 188 | View all user solutions | Challenge discussion

    Tree ConstructorNot Completed

    Solutions: 294 | View all user solutions | Challenge discussion

    Array Min JumpsNot Completed

    Solutions: 228 | View all user solutions | Challenge discussion

    Nearest Smaller ValuesNot Completed

    Solutions: 403 | View all user solutions | Challenge discussion

    Matrix SpiralNot Completed

    Solutions: 197 | View all user solutions | Challenge discussion

    Word SplitNot Completed

    Solutions: 364 | View all user solutions | Challenge discussion

    Pair SearchingNot Completed

    Solutions: 123 | View all user solutions | Challenge discussion

    Boggle SolverNot Completed

    Solutions: 95 | View all user solutions | Challenge discussion

    HTML ElementsNot Completed

    Solutions: 160 | View all user solutions | Challenge discussion

    Missing Digit IINot Completed

    Solutions: 154 | View all user solutions | Challenge discussion

    Palindromic SubstringNot Completed

    Solutions: 262 | View all user solutions | Challenge discussion

    Trapping WaterNot Completed

    Solutions: 153 | View all user solutions | Challenge discussion

    Matrix PathNot Completed

    Solutions: 77 | View all user solutions | Challenge discussion

    Seating StudentsNot Completed

    Solutions: 150 | View all user solutions | Challenge discussion

    Longest Matrix PathNot Completed

    Solutions: 70 | View all user solutions | Challenge discussion

    Min Window SubstringNot Completed

    Solutions: 153 | View all user solutions | Challenge discussion

    Matrix ChainsNot Completed

    Solutions: 67 | View all user solutions | Challenge discussion

    Histogram AreaNot Completed

    Solutions: 119 | View all user solutions | Challenge discussion

    Matching CharactersNot Completed

    Solutions: 173 | View all user solutions | Challenge discussion

    Ternary ConverterNot Completed

    Solutions: 92 | View all user solutions | Challenge discussion

    Linear CongruenceNot Completed

    Solutions: 56 | View all user solutions | Challenge discussion

    Formatted NumberNot Completed

    Solutions: 196 | View all user solutions | Challenge discussion

    Largest Row ColumnNot Completed

    Solutions: 55 | View all user solutions | Challenge discussion

    Eight QueensNot Completed

    Solutions: 963 | View all user solutions | Challenge discussion

    Three PointsNot Completed

    Solutions: 130 | View all user solutions | Challenge discussion

    Character RemovalNot Completed

    Solutions: 146 | View all user solutions | Challenge discussion

    Simple PasswordNot Completed

    Solutions: 195 | View all user solutions | Challenge discussion

    Preorder TraversalNot Completed

    Solutions: 89 | View all user solutions | Challenge discussion

    String ZigzagNot Completed

    Solutions: 95 | View all user solutions | Challenge discussion

    Off BinaryNot Completed

    Solutions: 83 | View all user solutions | Challenge discussion

    Longest ConsecutiveNot Completed

    Solutions: 297 | View all user solutions | Challenge discussion

    String ExpressionNot Completed

    Solutions: 140 | View all user solutions | Challenge discussion

    Charlie the DogNot Completed

    Solutions: 71 | View all user solutions | Challenge discussion

    Plus MinusNot Completed

    Solutions: 116 | View all user solutions | Challenge discussion

    Hard Difficulty

    Sudoku Quadrant CheckerNot Completed

    Solutions: 123 | View all user solutions | Challenge discussion

    Optimal AssignmentsNot Completed

    Solutions: 515 | View all user solutions | Challenge discussion

    Transitivity RelationsNot Completed

    Solutions: 417 | View all user solutions | Challenge discussion

    Shortest PathNot Completed

    Solutions: 1169 | View all user solutions | Challenge discussion

    Polynomial ExpansionNot Completed

    Solutions: 298 | View all user solutions | Challenge discussion

    CalculatorNot Completed

    Solutions: 1169 | View all user solutions | Challenge discussion

    Pattern ChaserNot Completed

    Solutions: 760 | View all user solutions | Challenge discussion

    Weighted PathNot Completed

    Solutions: 364 | View all user solutions | Challenge discussion

    RREF MatrixNot Completed

    Solutions: 134 | View all user solutions | Challenge discussion

    Intersecting LinesNot Completed

    Solutions: 576 | View all user solutions | Challenge discussion

    Kaprekars ConstantNot Completed

    Solutions: 4333 | View all user solutions | Challenge discussion

    Hamiltonian PathNot Completed

    Solutions: 144 | View all user solutions | Challenge discussion

    Step WalkingNot Completed

    Solutions: 110 | View all user solutions | Challenge discussion

    Gas StationNot Completed

    Solutions: 581 | View all user solutions | Challenge discussion

    Symmetric MatrixNot Completed

    Solutions: 408 | View all user solutions | Challenge discussion

    Switch SortNot Completed

    Solutions: 286 | View all user solutions | Challenge discussion

    Matrix DeterminantNot Completed

    Solutions: 271 | View all user solutions | Challenge discussion

    Queen CheckNot Completed

    Solutions: 470 | View all user solutions | Challenge discussion

    Noughts DeterminerNot Completed

    Solutions: 382 | View all user solutions | Challenge discussion

    Blackjack HighestNot Completed

    Solutions: 527 | View all user solutions | Challenge discussion

    Alphabet Run EncryptionNot Completed

    Solutions: 249 | View all user solutions | Challenge discussion

    Vertex CoveringNot Completed

    Solutions: 142 | View all user solutions | Challenge discussion

    Knight JumpsNot Completed

    Solutions: 523 | View all user solutions | Challenge discussion

    Farthest NodesNot Completed

    Solutions: 153 | View all user solutions | Challenge discussion

    Line OrderingNot Completed

    Solutions: 71 | View all user solutions | Challenge discussion

    Quick KnightNot Completed

    Solutions: 63 | View all user solutions | Challenge discussion

    Square FiguresNot Completed

    Solutions: 150 | View all user solutions | Challenge discussion

    Connect Four WinnerNot Completed

    Solutions: 110 | View all user solutions | Challenge discussion

    Array JumpingNot Completed

    Solutions: 81 | View all user solutions | Challenge discussion

    Matrix BorderNot Completed

    Solutions: 81 | View all user solutions | Challenge discussion

    Roman Numeral ReductionNot Completed

    Solutions: 96 | View all user solutions | Challenge discussion

    Parallel SumsNot Completed

    Solutions: 151 | View all user solutions | Challenge discussion

    LCSNot Completed

    Solutions: 92 | View all user solutions | Challenge discussion

    Nim WinnerNot Completed

    Solutions: 56 | View all user solutions | Challenge discussion

    Pascals TriangleNot Completed

    Solutions: 114 | View all user solutions | Challenge discussion

    Reverse Polish NotationNot Completed

    Solutions: 222 | View all user solutions | Challenge discussion

    Max Heap CheckerNot Completed

    Solutions: 106 | View all user solutions | Challenge discussion

    Chessboard TravelingNot Completed

    Solutions: 1844 | View all user solutions | Challenge discussion

    Matching CouplesNot Completed

    Solutions: 123 | View all user solutions | Challenge discussion

    Approaching FibonacciNot Completed

    Solutions: 143 | View all user solutions | Challenge discussion

    Simple SATNot Completed

    Solutions: 78 | View all user solutions | Challenge discussion

    Array CouplesNot Completed

    Solutions: 113 | View all user solutions | Challenge discussion

    Bracket CombinationsNot Completed

    Solutions: 138 | View all user solutions | Challenge discussion

    Counting AnagramsNot Completed

    Solutions: 164 | View all user solutions | Challenge discussion

    Array RotationNot Completed

    Solutions: 179 | View all user solutions | Challenge discussion

    Maximal SquareNot Completed

    Solutions: 1178 | View all user solutions | Challenge discussion

    Maximal RectangleNot Completed

    Solutions: 43 | View all user solutions | Challenge discussion

    Bipartite MatchingNot Completed

    Solutions: 48 | View all user solutions | Challenge discussion

    Pentagonal NumberNot Completed

    Solutions: 1274 | View all user solutions | Challenge discussion

    City TrafficNot Completed

    Solutions: 47 | View all user solutions | Challenge discussion

    Convex Hull PointsNot Completed

    Solutions: 30 | View all user solutions | Challenge discussion

    Wildcard CharactersNot Completed

    Solutions: 81 | View all user solutions | Challenge discussion

    Tetris MoveNot Completed

    Solutions: 27 | View all user solutions | Challenge discussion

    Difficulty

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    • optimization 22
    • matrix 21
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    • game 10
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    • sequences 7
    • stack 7
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    • chess 5
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    • geometry 4
    • linear algebra 4
    • prime numbers 3
    • set theory 3
    • heap 3
    • bitwise operation 2
    • cache 1