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    Maximal SquareNot Completed

    Solutions: 3866 | View user solutions | Added 05/21/16

    Pentagonal NumberNot Completed

    Solutions: 3942 | View user solutions | Added 08/31/16

    Eight QueensNot Completed

    Solutions: 3027 | View user solutions | Added 11/06/16

    Free Challenges

    Longest WordNot Completed

    Solutions: 100209 | Step-by-step solution | Challenge discussion

    First FactorialNot Completed

    Solutions: 143224 | Step-by-step solution | Challenge discussion

    First ReverseNot Completed

    Solutions: 157922 | Step-by-step solution | Challenge discussion

    Letter ChangesNot Completed

    Solutions: 101030 | Step-by-step solution | Challenge discussion

    Simple AddingNot Completed

    Solutions: 81804 | Step-by-step solution | Challenge discussion

    Letter CapitalizeNot Completed

    Solutions: 69868 | Step-by-step solution | Challenge discussion

    Simple SymbolsNot Completed

    Solutions: 59448 | Step-by-step solution | Challenge discussion

    Check NumsNot Completed

    Solutions: 59778 | Step-by-step solution | Challenge discussion

    Time ConvertNot Completed

    Solutions: 46248 | Step-by-step solution | Challenge discussion

    Alphabet SoupNot Completed

    Solutions: 41553 | Step-by-step solution | Challenge discussion

    Kaprekars ConstantNot Completed

    Solutions: 9635 | View all user solutions | Challenge discussion

    Chessboard TravelingNot Completed

    Solutions: 4153 | View all user solutions | Challenge discussion

    Maximal SquareNot Completed

    Solutions: 3866 | View all user solutions | Challenge discussion

    Pentagonal NumberNot Completed

    Solutions: 3942 | View all user solutions | Challenge discussion

    Correct PathNot Completed

    Solutions: 2734 | View all user solutions | Challenge discussion

    Scale BalancingNot Completed

    Solutions: 4063 | View all user solutions | Challenge discussion

    Vowel SquareNot Completed

    Solutions: 2547 | View all user solutions | Challenge discussion

    Eight QueensNot Completed

    Solutions: 3027 | View all user solutions | Challenge discussion

    Closest Enemy IINot Completed

    Solutions: 2484 | View all user solutions | Challenge discussion

    Questions MarksNot Completed

    Solutions: 6527 | View all user solutions | Challenge discussion

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    Easy Difficulty

    First ReverseNot Completed

    Solutions: 157922 | Step-by-step solution | Challenge discussion

    First FactorialNot Completed

    Solutions: 143224 | Step-by-step solution | Challenge discussion

    Longest WordNot Completed

    Solutions: 100209 | Step-by-step solution | Challenge discussion

    Letter ChangesNot Completed

    Solutions: 101030 | Step-by-step solution | Challenge discussion

    Simple AddingNot Completed

    Solutions: 81804 | Step-by-step solution | Challenge discussion

    Letter CapitalizeNot Completed

    Solutions: 69868 | Step-by-step solution | Challenge discussion

    Simple SymbolsNot Completed

    Solutions: 59448 | Step-by-step solution | Challenge discussion

    Check NumsNot Completed

    Solutions: 59778 | Step-by-step solution | Challenge discussion

    Time ConvertNot Completed

    Solutions: 46248 | Step-by-step solution | Challenge discussion

    Alphabet SoupNot Completed

    Solutions: 41553 | Step-by-step solution | Challenge discussion

    AB CheckNot Completed

    Solutions: 17896 | Step-by-step solution | Challenge discussion

    Vowel CountNot Completed

    Solutions: 16411 | Step-by-step solution | Challenge discussion

    Word CountNot Completed

    Solutions: 15405 | Step-by-step solution | Challenge discussion

    Ex OhNot Completed

    Solutions: 15084 | Step-by-step solution | Challenge discussion

    PalindromeNot Completed

    Solutions: 17693 | Step-by-step solution | Challenge discussion

    Arith GeoNot Completed

    Solutions: 14160 | Step-by-step solution | Challenge discussion

    Array Addition INot Completed

    Solutions: 9229 | Step-by-step solution | Challenge discussion

    Letter Count INot Completed

    Solutions: 8397 | Step-by-step solution | Challenge discussion

    Second GreatLowNot Completed

    Solutions: 13927 | Step-by-step solution | Challenge discussion

    Division StringifiedNot Completed

    Solutions: 10357 | Step-by-step solution | Challenge discussion

    Counting Minutes INot Completed

    Solutions: 6154 | Step-by-step solution | Challenge discussion

    Mean ModeNot Completed

    Solutions: 8023 | Step-by-step solution | Challenge discussion

    Dash InsertNot Completed

    Solutions: 9111 | Step-by-step solution | Challenge discussion

    Swap CaseNot Completed

    Solutions: 8499 | Step-by-step solution | Challenge discussion

    Number AdditionNot Completed

    Solutions: 8443 | Step-by-step solution | Challenge discussion

    Third GreatestNot Completed

    Solutions: 8099 | Step-by-step solution | Challenge discussion

    Powers of TwoNot Completed

    Solutions: 8743 | Step-by-step solution | Challenge discussion

    Additive PersistenceNot Completed

    Solutions: 6366 | Step-by-step solution | Challenge discussion

    Multiplicative PersistenceNot Completed

    Solutions: 4916 | Step-by-step solution | Challenge discussion

    Off Line MinimumNot Completed

    Solutions: 6574 | Step-by-step solution | Challenge discussion

    Changing SequenceNot Completed

    Solutions: 3212 | Step-by-step solution | Challenge discussion

    Overlapping RangesNot Completed

    Solutions: 2910 | Step-by-step solution | Challenge discussion

    SuperincreasingNot Completed

    Solutions: 2928 | Step-by-step solution | Challenge discussion

    Hamming DistanceNot Completed

    Solutions: 2046 | Step-by-step solution | Challenge discussion

    Rectangle AreaNot Completed

    Solutions: 2462 | Step-by-step solution | Challenge discussion

    Bitwise OneNot Completed

    Solutions: 1981 | Step-by-step solution | Challenge discussion

    Other ProductsNot Completed

    Solutions: 2082 | Step-by-step solution | Challenge discussion

    Wave SortingNot Completed

    Solutions: 1459 | Step-by-step solution | Challenge discussion

    Array MatchingNot Completed

    Solutions: 1882 | Step-by-step solution | Challenge discussion

    Binary ReversalNot Completed

    Solutions: 1652 | Step-by-step solution | Challenge discussion

    Longest Increasing SequenceNot Completed

    Solutions: 1662 | Step-by-step solution | Challenge discussion

    Even PairsNot Completed

    Solutions: 1382 | Step-by-step solution | Challenge discussion

    Next PalindromeNot Completed

    Solutions: 1324 | Step-by-step solution | Challenge discussion

    Largest PairNot Completed

    Solutions: 1565 | Step-by-step solution | Challenge discussion

    Nonrepeating CharacterNot Completed

    Solutions: 1955 | Step-by-step solution | Challenge discussion

    Two SumNot Completed

    Solutions: 2634 | Step-by-step solution | Challenge discussion

    Bitwise TwoNot Completed

    Solutions: 868 | Step-by-step solution | Challenge discussion

    Power Set CountNot Completed

    Solutions: 1208 | Step-by-step solution | Challenge discussion

    Product DigitsNot Completed

    Solutions: 1516 | Step-by-step solution | Challenge discussion

    Palindrome CreatorNot Completed

    Solutions: 1540 | Step-by-step solution | Challenge discussion

    Basic Roman NumeralsNot Completed

    Solutions: 927 | Step-by-step solution | Challenge discussion

    Food DistributionNot Completed

    Solutions: 865 | Step-by-step solution | Challenge discussion

    Three SumNot Completed

    Solutions: 937 | Step-by-step solution | Challenge discussion

    Correct PathNot Completed

    Solutions: 2734 | Step-by-step solution | Challenge discussion

    Scale BalancingNot Completed

    Solutions: 4063 | Step-by-step solution | Challenge discussion

    Three NumbersNot Completed

    Solutions: 894 | Step-by-step solution | Challenge discussion

    Alphabet SearchingNot Completed

    Solutions: 766 | Step-by-step solution | Challenge discussion

    Time DifferenceNot Completed

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

    Triangle RowNot Completed

    Solutions: 454 | Step-by-step solution | Challenge discussion

    Vowel SquareNot Completed

    Solutions: 2547 | Step-by-step solution | Challenge discussion

    Closest EnemyNot Completed

    Solutions: 738 | Step-by-step solution | Challenge discussion

    Closest Enemy IINot Completed

    Solutions: 2484 | Step-by-step solution | Challenge discussion

    Number StreamNot Completed

    Solutions: 512 | Step-by-step solution | Challenge discussion

    Largest FourNot Completed

    Solutions: 860 | Step-by-step solution | Challenge discussion

    Distinct CharactersNot Completed

    Solutions: 525 | Step-by-step solution | Challenge discussion

    Questions MarksNot Completed

    Solutions: 6527 | Step-by-step solution | Challenge discussion

    Camel CaseNot Completed

    Solutions: 616 | Step-by-step solution | Challenge discussion

    ASCII ConversionNot Completed

    Solutions: 430 | Step-by-step solution | Challenge discussion

    Simple EvensNot Completed

    Solutions: 574 | Step-by-step solution | Challenge discussion

    Snake CaseNot Completed

    Solutions: 557 | Step-by-step solution | Challenge discussion

    Sum MultiplierNot Completed

    Solutions: 635 | Step-by-step solution | Challenge discussion

    String MergeNot Completed

    Solutions: 599 | Step-by-step solution | Challenge discussion

    One DecrementedNot Completed

    Solutions: 539 | Step-by-step solution | Challenge discussion

    Element MergerNot Completed

    Solutions: 603 | Step-by-step solution | Challenge discussion

    GCFNot Completed

    Solutions: 579 | Step-by-step solution | Challenge discussion

    Serial NumberNot Completed

    Solutions: 721 | Step-by-step solution | Challenge discussion

    String PeriodsNot Completed

    Solutions: 603 | Step-by-step solution | Challenge discussion

    Palindrome SwapperNot Completed

    Solutions: 478 | Step-by-step solution | Challenge discussion

    Remove BracketsNot Completed

    Solutions: 636 | Step-by-step solution | Challenge discussion

    Command LineNot Completed

    Solutions: 287 | Step-by-step solution | Challenge discussion

    Star RatingNot Completed

    Solutions: 957 | Step-by-step solution | Challenge discussion

    Moving MedianNot Completed

    Solutions: 410 | Step-by-step solution | Challenge discussion

    Group TotalsNot Completed

    Solutions: 770 | Step-by-step solution | Challenge discussion

    String ChangesNot Completed

    Solutions: 184 | Step-by-step solution | Challenge discussion

    FizzBuzzNot Completed

    Solutions: 783 | Step-by-step solution | Challenge discussion

    H DistanceNot Completed

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

    Different CasesNot Completed

    Solutions: 194 | Step-by-step solution | Challenge discussion

    Medium Difficulty

    Prime TimeNot Completed

    Solutions: 12839 | Step-by-step solution | Challenge discussion

    Run Length Not Completed

    Solutions: 8946 | Step-by-step solution | Challenge discussion

    Prime MoverNot Completed

    Solutions: 7686 | Step-by-step solution | Challenge discussion

    Palindrome TwoNot Completed

    Solutions: 7818 | Step-by-step solution | Challenge discussion

    DivisionNot Completed

    Solutions: 6877 | Step-by-step solution | Challenge discussion

    String ScrambleNot Completed

    Solutions: 7698 | Step-by-step solution | Challenge discussion

    Arith Geo IINot Completed

    Solutions: 5188 | Step-by-step solution | Challenge discussion

    Array AdditionNot Completed

    Solutions: 4794 | Step-by-step solution | Challenge discussion

    Binary ConverterNot Completed

    Solutions: 4795 | Step-by-step solution | Challenge discussion

    Letter CountNot Completed

    Solutions: 4690 | Step-by-step solution | Challenge discussion

    Caesar CipherNot Completed

    Solutions: 5517 | Step-by-step solution | Challenge discussion

    Simple ModeNot Completed

    Solutions: 5190 | Step-by-step solution | Challenge discussion

    ConsecutiveNot Completed

    Solutions: 4289 | Step-by-step solution | Challenge discussion

    Formatted DivisionNot Completed

    Solutions: 3952 | Step-by-step solution | Challenge discussion

    Counting MinutesNot Completed

    Solutions: 2970 | View all user solutions | Challenge discussion

    Permutation StepNot Completed

    Solutions: 3711 | View all user solutions | Challenge discussion

    Prime CheckerNot Completed

    Solutions: 2665 | View all user solutions | Challenge discussion

    Dash Insert IINot Completed

    Solutions: 5081 | View all user solutions | Challenge discussion

    Swap IINot Completed

    Solutions: 3207 | View all user solutions | Challenge discussion

    Number SearchNot Completed

    Solutions: 3506 | View all user solutions | Challenge discussion

    Triple DoubleNot Completed

    Solutions: 3235 | View all user solutions | Challenge discussion

    Bracket MatcherNot Completed

    Solutions: 2959 | View all user solutions | Challenge discussion

    String ReductionNot Completed

    Solutions: 2568 | View all user solutions | Challenge discussion

    ThreeFive MultiplesNot Completed

    Solutions: 2934 | View all user solutions | Challenge discussion

    Binary Search Tree LCANot Completed

    Solutions: 453 | View all user solutions | Challenge discussion

    Coin DeterminerNot Completed

    Solutions: 2425 | View all user solutions | Challenge discussion

    Fibonacci CheckerNot Completed

    Solutions: 2819 | View all user solutions | Challenge discussion

    Multiple BracketsNot Completed

    Solutions: 2450 | View all user solutions | Challenge discussion

    Most Free TimeNot Completed

    Solutions: 1572 | View all user solutions | Challenge discussion

    Overlapping RectanglesNot Completed

    Solutions: 1700 | View all user solutions | Challenge discussion

    Look Say SequenceNot Completed

    Solutions: 1545 | View all user solutions | Challenge discussion

    Distinct ListNot Completed

    Solutions: 2696 | View all user solutions | Challenge discussion

    Number EncodingNot Completed

    Solutions: 1555 | View all user solutions | Challenge discussion

    Stock PickerNot Completed

    Solutions: 936 | View all user solutions | Challenge discussion

    Max SubarrayNot Completed

    Solutions: 828 | View all user solutions | Challenge discussion

    Missing DigitNot Completed

    Solutions: 510 | View all user solutions | Challenge discussion

    K Unique CharactersNot Completed

    Solutions: 923 | View all user solutions | Challenge discussion

    Bitmap HolesNot Completed

    Solutions: 392 | View all user solutions | Challenge discussion

    Symmetric TreeNot Completed

    Solutions: 338 | View all user solutions | Challenge discussion

    Binary Tree LCANot Completed

    Solutions: 232 | View all user solutions | Challenge discussion

    LRU CacheNot Completed

    Solutions: 340 | View all user solutions | Challenge discussion

    Tree ConstructorNot Completed

    Solutions: 457 | View all user solutions | Challenge discussion

    Array Min JumpsNot Completed

    Solutions: 289 | View all user solutions | Challenge discussion

    Nearest Smaller ValuesNot Completed

    Solutions: 499 | View all user solutions | Challenge discussion

    Matrix SpiralNot Completed

    Solutions: 392 | View all user solutions | Challenge discussion

    Word SplitNot Completed

    Solutions: 594 | View all user solutions | Challenge discussion

    Pair SearchingNot Completed

    Solutions: 154 | View all user solutions | Challenge discussion

    Boggle SolverNot Completed

    Solutions: 140 | View all user solutions | Challenge discussion

    HTML ElementsNot Completed

    Solutions: 490 | View all user solutions | Challenge discussion

    Missing Digit IINot Completed

    Solutions: 191 | View all user solutions | Challenge discussion

    Palindromic SubstringNot Completed

    Solutions: 377 | View all user solutions | Challenge discussion

    Trapping WaterNot Completed

    Solutions: 210 | View all user solutions | Challenge discussion

    Matrix PathNot Completed

    Solutions: 311 | View all user solutions | Challenge discussion

    Seating StudentsNot Completed

    Solutions: 414 | View all user solutions | Challenge discussion

    Longest Matrix PathNot Completed

    Solutions: 94 | View all user solutions | Challenge discussion

    Min Window SubstringNot Completed

    Solutions: 577 | View all user solutions | Challenge discussion

    Matrix ChainsNot Completed

    Solutions: 94 | View all user solutions | Challenge discussion

    Histogram AreaNot Completed

    Solutions: 311 | View all user solutions | Challenge discussion

    Matching CharactersNot Completed

    Solutions: 307 | View all user solutions | Challenge discussion

    Ternary ConverterNot Completed

    Solutions: 118 | View all user solutions | Challenge discussion

    Linear CongruenceNot Completed

    Solutions: 71 | View all user solutions | Challenge discussion

    Formatted NumberNot Completed

    Solutions: 255 | View all user solutions | Challenge discussion

    Largest Row ColumnNot Completed

    Solutions: 76 | View all user solutions | Challenge discussion

    Eight QueensNot Completed

    Solutions: 3027 | View all user solutions | Challenge discussion

    Three PointsNot Completed

    Solutions: 179 | View all user solutions | Challenge discussion

    Character RemovalNot Completed

    Solutions: 214 | View all user solutions | Challenge discussion

    Simple PasswordNot Completed

    Solutions: 397 | View all user solutions | Challenge discussion

    Preorder TraversalNot Completed

    Solutions: 135 | View all user solutions | Challenge discussion

    String ZigzagNot Completed

    Solutions: 130 | View all user solutions | Challenge discussion

    Off BinaryNot Completed

    Solutions: 114 | View all user solutions | Challenge discussion

    Longest ConsecutiveNot Completed

    Solutions: 420 | View all user solutions | Challenge discussion

    String ExpressionNot Completed

    Solutions: 182 | View all user solutions | Challenge discussion

    Charlie the DogNot Completed

    Solutions: 209 | View all user solutions | Challenge discussion

    Plus MinusNot Completed

    Solutions: 347 | View all user solutions | Challenge discussion

    PrimesNot Completed

    Solutions: 132 | View all user solutions | Challenge discussion

    String CalculateNot Completed

    Solutions: 92 | View all user solutions | Challenge discussion

    Hard Difficulty

    Sudoku Quadrant CheckerNot Completed

    Solutions: 179 | View all user solutions | Challenge discussion

    Optimal AssignmentsNot Completed

    Solutions: 587 | View all user solutions | Challenge discussion

    Transitivity RelationsNot Completed

    Solutions: 441 | View all user solutions | Challenge discussion

    Shortest PathNot Completed

    Solutions: 1391 | View all user solutions | Challenge discussion

    Polynomial ExpansionNot Completed

    Solutions: 321 | View all user solutions | Challenge discussion

    CalculatorNot Completed

    Solutions: 1229 | View all user solutions | Challenge discussion

    Pattern ChaserNot Completed

    Solutions: 819 | View all user solutions | Challenge discussion

    Weighted PathNot Completed

    Solutions: 390 | View all user solutions | Challenge discussion

    RREF MatrixNot Completed

    Solutions: 140 | View all user solutions | Challenge discussion

    Intersecting LinesNot Completed

    Solutions: 610 | View all user solutions | Challenge discussion

    Kaprekars ConstantNot Completed

    Solutions: 9635 | View all user solutions | Challenge discussion

    Hamiltonian PathNot Completed

    Solutions: 173 | View all user solutions | Challenge discussion

    Step WalkingNot Completed

    Solutions: 150 | View all user solutions | Challenge discussion

    Gas StationNot Completed

    Solutions: 679 | View all user solutions | Challenge discussion

    Symmetric MatrixNot Completed

    Solutions: 439 | View all user solutions | Challenge discussion

    Switch SortNot Completed

    Solutions: 343 | View all user solutions | Challenge discussion

    Matrix DeterminantNot Completed

    Solutions: 285 | View all user solutions | Challenge discussion

    Queen CheckNot Completed

    Solutions: 645 | View all user solutions | Challenge discussion

    Noughts DeterminerNot Completed

    Solutions: 398 | View all user solutions | Challenge discussion

    Blackjack HighestNot Completed

    Solutions: 616 | View all user solutions | Challenge discussion

    Alphabet Run EncryptionNot Completed

    Solutions: 283 | View all user solutions | Challenge discussion

    Vertex CoveringNot Completed

    Solutions: 159 | View all user solutions | Challenge discussion

    Knight JumpsNot Completed

    Solutions: 547 | View all user solutions | Challenge discussion

    Farthest NodesNot Completed

    Solutions: 240 | View all user solutions | Challenge discussion

    Line OrderingNot Completed

    Solutions: 104 | View all user solutions | Challenge discussion

    Quick KnightNot Completed

    Solutions: 83 | View all user solutions | Challenge discussion

    Square FiguresNot Completed

    Solutions: 190 | View all user solutions | Challenge discussion

    Connect Four WinnerNot Completed

    Solutions: 133 | View all user solutions | Challenge discussion

    Array JumpingNot Completed

    Solutions: 99 | View all user solutions | Challenge discussion

    Matrix BorderNot Completed

    Solutions: 95 | View all user solutions | Challenge discussion

    Roman Numeral ReductionNot Completed

    Solutions: 120 | View all user solutions | Challenge discussion

    Parallel SumsNot Completed

    Solutions: 202 | View all user solutions | Challenge discussion

    LCSNot Completed

    Solutions: 137 | View all user solutions | Challenge discussion

    Nim WinnerNot Completed

    Solutions: 65 | View all user solutions | Challenge discussion

    Pascals TriangleNot Completed

    Solutions: 148 | View all user solutions | Challenge discussion

    Reverse Polish NotationNot Completed

    Solutions: 252 | View all user solutions | Challenge discussion

    Max Heap CheckerNot Completed

    Solutions: 120 | View all user solutions | Challenge discussion

    Chessboard TravelingNot Completed

    Solutions: 4153 | View all user solutions | Challenge discussion

    Matching CouplesNot Completed

    Solutions: 201 | View all user solutions | Challenge discussion

    Approaching FibonacciNot Completed

    Solutions: 174 | View all user solutions | Challenge discussion

    Simple SATNot Completed

    Solutions: 89 | View all user solutions | Challenge discussion

    Array CouplesNot Completed

    Solutions: 146 | View all user solutions | Challenge discussion

    Bracket CombinationsNot Completed

    Solutions: 164 | View all user solutions | Challenge discussion

    Counting AnagramsNot Completed

    Solutions: 230 | View all user solutions | Challenge discussion

    Array RotationNot Completed

    Solutions: 407 | View all user solutions | Challenge discussion

    Maximal SquareNot Completed

    Solutions: 3866 | View all user solutions | Challenge discussion

    Maximal RectangleNot Completed

    Solutions: 76 | View all user solutions | Challenge discussion

    Bipartite MatchingNot Completed

    Solutions: 98 | View all user solutions | Challenge discussion

    Pentagonal NumberNot Completed

    Solutions: 3942 | View all user solutions | Challenge discussion

    City TrafficNot Completed

    Solutions: 177 | View all user solutions | Challenge discussion

    Convex Hull PointsNot Completed

    Solutions: 45 | View all user solutions | Challenge discussion

    Wildcard CharactersNot Completed

    Solutions: 223 | View all user solutions | Challenge discussion

    Tetris MoveNot Completed

    Solutions: 156 | View all user solutions | Challenge discussion

    WildcardsNot Completed

    Solutions: 105 | View all user solutions | Challenge discussion

    Difficulty

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    • array 71
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    • algebra 10
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    • combinatorics 9
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    • sequences 7
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