• Challenges
  • Algorithms
  • Recently Added

    Maximal SquareNot Completed

    Solutions: 1939 | View user solutions | Added 05/21/16

    Pentagonal NumberNot Completed

    Solutions: 2037 | View user solutions | Added 08/31/16

    Eight QueensNot Completed

    Solutions: 1609 | View user solutions | Added 11/06/16

    Free Challenges

    Longest WordNot Completed

    Solutions: 83583 | Step-by-step solution | Challenge discussion

    First FactorialNot Completed

    Solutions: 108588 | Step-by-step solution | Challenge discussion

    First ReverseNot Completed

    Solutions: 128276 | Step-by-step solution | Challenge discussion

    Letter ChangesNot Completed

    Solutions: 80245 | Step-by-step solution | Challenge discussion

    Simple AddingNot Completed

    Solutions: 65264 | Step-by-step solution | Challenge discussion

    Letter CapitalizeNot Completed

    Solutions: 55507 | Step-by-step solution | Challenge discussion

    Simple SymbolsNot Completed

    Solutions: 47195 | Step-by-step solution | Challenge discussion

    Check NumsNot Completed

    Solutions: 47749 | Step-by-step solution | Challenge discussion

    Time ConvertNot Completed

    Solutions: 36436 | Step-by-step solution | Challenge discussion

    Alphabet SoupNot Completed

    Solutions: 33364 | Step-by-step solution | Challenge discussion

    Kaprekars ConstantNot Completed

    Solutions: 6316 | View all user solutions | Challenge discussion

    Chessboard TravelingNot Completed

    Solutions: 2750 | View all user solutions | Challenge discussion

    Maximal SquareNot Completed

    Solutions: 1939 | View all user solutions | Challenge discussion

    Pentagonal NumberNot Completed

    Solutions: 2037 | View all user solutions | Challenge discussion

    Correct PathNot Completed

    Solutions: 1951 | View all user solutions | Challenge discussion

    Scale BalancingNot Completed

    Solutions: 2698 | View all user solutions | Challenge discussion

    Vowel SquareNot Completed

    Solutions: 1749 | View all user solutions | Challenge discussion

    Eight QueensNot Completed

    Solutions: 1609 | View all user solutions | Challenge discussion

    Closest Enemy IINot Completed

    Solutions: 1580 | View all user solutions | Challenge discussion

    Questions MarksNot Completed

    Solutions: 4500 | View all user solutions | Challenge discussion

    Become a Premium Member

    With our large collection of challenges, tutorials, and solutions, we make it easy for you to become a better coder, prepare for interviews, and learn new skills from more experienced coders.

    “Daniel - Thanks so much for making Coderbyte! We still recommend it to people.” ― Shawn Drost
    • 200+ Coding Challenges
    • Mock Interview Questions
    • 900,000+ Code Solutions
    • Algorithm Tutorials
    • Interview Prep Courses

    Easy Difficulty

    First ReverseNot Completed

    Solutions: 128276 | Step-by-step solution | Challenge discussion

    First FactorialNot Completed

    Solutions: 108588 | Step-by-step solution | Challenge discussion

    Longest WordNot Completed

    Solutions: 83583 | Step-by-step solution | Challenge discussion

    Letter ChangesNot Completed

    Solutions: 80245 | Step-by-step solution | Challenge discussion

    Simple AddingNot Completed

    Solutions: 65264 | Step-by-step solution | Challenge discussion

    Letter CapitalizeNot Completed

    Solutions: 55507 | Step-by-step solution | Challenge discussion

    Simple SymbolsNot Completed

    Solutions: 47195 | Step-by-step solution | Challenge discussion

    Check NumsNot Completed

    Solutions: 47749 | Step-by-step solution | Challenge discussion

    Time ConvertNot Completed

    Solutions: 36436 | Step-by-step solution | Challenge discussion

    Alphabet SoupNot Completed

    Solutions: 33364 | Step-by-step solution | Challenge discussion

    AB CheckNot Completed

    Solutions: 17238 | Step-by-step solution | Challenge discussion

    Vowel CountNot Completed

    Solutions: 15828 | Step-by-step solution | Challenge discussion

    Word CountNot Completed

    Solutions: 14934 | Step-by-step solution | Challenge discussion

    Ex OhNot Completed

    Solutions: 14644 | Step-by-step solution | Challenge discussion

    PalindromeNot Completed

    Solutions: 17076 | Step-by-step solution | Challenge discussion

    Arith GeoNot Completed

    Solutions: 13614 | Step-by-step solution | Challenge discussion

    Array Addition INot Completed

    Solutions: 8821 | Step-by-step solution | Challenge discussion

    Letter Count INot Completed

    Solutions: 8043 | Step-by-step solution | Challenge discussion

    Second GreatLowNot Completed

    Solutions: 13341 | Step-by-step solution | Challenge discussion

    Division StringifiedNot Completed

    Solutions: 9949 | Step-by-step solution | Challenge discussion

    Counting Minutes INot Completed

    Solutions: 5932 | Step-by-step solution | Challenge discussion

    Mean ModeNot Completed

    Solutions: 7722 | Step-by-step solution | Challenge discussion

    Dash InsertNot Completed

    Solutions: 8767 | Step-by-step solution | Challenge discussion

    Swap CaseNot Completed

    Solutions: 8262 | Step-by-step solution | Challenge discussion

    Number AdditionNot Completed

    Solutions: 8177 | Step-by-step solution | Challenge discussion

    Third GreatestNot Completed

    Solutions: 7566 | Step-by-step solution | Challenge discussion

    Powers of TwoNot Completed

    Solutions: 8454 | Step-by-step solution | Challenge discussion

    Additive PersistenceNot Completed

    Solutions: 6040 | Step-by-step solution | Challenge discussion

    Multiplicative PersistenceNot Completed

    Solutions: 4642 | Step-by-step solution | Challenge discussion

    Off Line MinimumNot Completed

    Solutions: 6266 | Step-by-step solution | Challenge discussion

    Changing SequenceNot Completed

    Solutions: 2650 | Step-by-step solution | Challenge discussion

    Overlapping RangesNot Completed

    Solutions: 2661 | Step-by-step solution | Challenge discussion

    SuperincreasingNot Completed

    Solutions: 2714 | Step-by-step solution | Challenge discussion

    Hamming DistanceNot Completed

    Solutions: 1861 | Step-by-step solution | Challenge discussion

    Rectangle AreaNot Completed

    Solutions: 2256 | Step-by-step solution | Challenge discussion

    Bitwise OneNot Completed

    Solutions: 1832 | Step-by-step solution | Challenge discussion

    Other ProductsNot Completed

    Solutions: 1908 | Step-by-step solution | Challenge discussion

    Wave SortingNot Completed

    Solutions: 1311 | Step-by-step solution | Challenge discussion

    Array MatchingNot Completed

    Solutions: 1639 | Step-by-step solution | Challenge discussion

    Binary ReversalNot Completed

    Solutions: 1349 | Step-by-step solution | Challenge discussion

    Longest Increasing SequenceNot Completed

    Solutions: 1315 | Step-by-step solution | Challenge discussion

    Even PairsNot Completed

    Solutions: 1242 | Step-by-step solution | Challenge discussion

    Next PalindromeNot Completed

    Solutions: 1086 | Step-by-step solution | Challenge discussion

    Largest PairNot Completed

    Solutions: 1435 | Step-by-step solution | Challenge discussion

    Nonrepeating CharacterNot Completed

    Solutions: 1110 | Step-by-step solution | Challenge discussion

    Two SumNot Completed

    Solutions: 2004 | Step-by-step solution | Challenge discussion

    Bitwise TwoNot Completed

    Solutions: 780 | Step-by-step solution | Challenge discussion

    Power Set CountNot Completed

    Solutions: 1121 | Step-by-step solution | Challenge discussion

    Product DigitsNot Completed

    Solutions: 1394 | Step-by-step solution | Challenge discussion

    Palindrome CreatorNot Completed

    Solutions: 1199 | Step-by-step solution | Challenge discussion

    Basic Roman NumeralsNot Completed

    Solutions: 780 | Step-by-step solution | Challenge discussion

    Food DistributionNot Completed

    Solutions: 702 | Step-by-step solution | Challenge discussion

    Three SumNot Completed

    Solutions: 805 | Step-by-step solution | Challenge discussion

    Correct PathNot Completed

    Solutions: 1951 | Step-by-step solution | Challenge discussion

    Scale BalancingNot Completed

    Solutions: 2698 | Step-by-step solution | Challenge discussion

    Three NumbersNot Completed

    Solutions: 794 | Step-by-step solution | Challenge discussion

    Alphabet SearchingNot Completed

    Solutions: 664 | Step-by-step solution | Challenge discussion

    Time DifferenceNot Completed

    Solutions: 431 | Step-by-step solution | Challenge discussion

    Triangle RowNot Completed

    Solutions: 405 | Step-by-step solution | Challenge discussion

    Vowel SquareNot Completed

    Solutions: 1749 | Step-by-step solution | Challenge discussion

    Closest EnemyNot Completed

    Solutions: 632 | Step-by-step solution | Challenge discussion

    Closest Enemy IINot Completed

    Solutions: 1580 | Step-by-step solution | Challenge discussion

    Number StreamNot Completed

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

    Largest FourNot Completed

    Solutions: 614 | Step-by-step solution | Challenge discussion

    Distinct CharactersNot Completed

    Solutions: 450 | Step-by-step solution | Challenge discussion

    Questions MarksNot Completed

    Solutions: 4500 | Step-by-step solution | Challenge discussion

    Camel CaseNot Completed

    Solutions: 529 | Step-by-step solution | Challenge discussion

    ASCII ConversionNot Completed

    Solutions: 372 | Step-by-step solution | Challenge discussion

    Simple EvensNot Completed

    Solutions: 506 | Step-by-step solution | Challenge discussion

    Snake CaseNot Completed

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

    Sum MultiplierNot Completed

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

    String MergeNot Completed

    Solutions: 516 | Step-by-step solution | Challenge discussion

    One DecrementedNot Completed

    Solutions: 479 | Step-by-step solution | Challenge discussion

    Element MergerNot Completed

    Solutions: 511 | Step-by-step solution | Challenge discussion

    GCFNot Completed

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

    Serial NumberNot Completed

    Solutions: 643 | Step-by-step solution | Challenge discussion

    String PeriodsNot Completed

    Solutions: 542 | Step-by-step solution | Challenge discussion

    Palindrome SwapperNot Completed

    Solutions: 352 | Step-by-step solution | Challenge discussion

    Remove BracketsNot Completed

    Solutions: 506 | Step-by-step solution | Challenge discussion

    Command LineNot Completed

    Solutions: 238 | Step-by-step solution | Challenge discussion

    Star RatingNot Completed

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

    Moving MedianNot Completed

    Solutions: 209 | Step-by-step solution | Challenge discussion

    Group TotalsNot Completed

    Solutions: 229 | Step-by-step solution | Challenge discussion

    String ChangesNot Completed

    Solutions: 95 | Step-by-step solution | Challenge discussion

    FizzBuzzNot Completed

    Solutions: 146 | Step-by-step solution | Challenge discussion

    H DistanceNot Completed

    Solutions: 84 | Step-by-step solution | Challenge discussion

    Different CasesNot Completed

    Solutions: 93 | Step-by-step solution | Challenge discussion

    Medium Difficulty

    Prime TimeNot Completed

    Solutions: 12175 | Step-by-step solution | Challenge discussion

    Run Length Not Completed

    Solutions: 8697 | Step-by-step solution | Challenge discussion

    Prime MoverNot Completed

    Solutions: 7519 | Step-by-step solution | Challenge discussion

    Palindrome TwoNot Completed

    Solutions: 7226 | Step-by-step solution | Challenge discussion

    DivisionNot Completed

    Solutions: 6708 | Step-by-step solution | Challenge discussion

    String ScrambleNot Completed

    Solutions: 7382 | Step-by-step solution | Challenge discussion

    Arith Geo IINot Completed

    Solutions: 5054 | Step-by-step solution | Challenge discussion

    Array AdditionNot Completed

    Solutions: 4526 | Step-by-step solution | Challenge discussion

    Binary ConverterNot Completed

    Solutions: 4586 | Step-by-step solution | Challenge discussion

    Letter CountNot Completed

    Solutions: 4541 | Step-by-step solution | Challenge discussion

    Caesar CipherNot Completed

    Solutions: 5213 | Step-by-step solution | Challenge discussion

    Simple ModeNot Completed

    Solutions: 5057 | Step-by-step solution | Challenge discussion

    ConsecutiveNot Completed

    Solutions: 4151 | Step-by-step solution | Challenge discussion

    Formatted DivisionNot Completed

    Solutions: 3856 | Step-by-step solution | Challenge discussion

    Counting MinutesNot Completed

    Solutions: 2828 | View all user solutions | Challenge discussion

    Permutation StepNot Completed

    Solutions: 3378 | View all user solutions | Challenge discussion

    Prime CheckerNot Completed

    Solutions: 2596 | View all user solutions | Challenge discussion

    Dash Insert IINot Completed

    Solutions: 4976 | View all user solutions | Challenge discussion

    Swap IINot Completed

    Solutions: 2778 | View all user solutions | Challenge discussion

    Number SearchNot Completed

    Solutions: 3406 | View all user solutions | Challenge discussion

    Triple DoubleNot Completed

    Solutions: 3155 | View all user solutions | Challenge discussion

    Bracket MatcherNot Completed

    Solutions: 2880 | View all user solutions | Challenge discussion

    String ReductionNot Completed

    Solutions: 2373 | View all user solutions | Challenge discussion

    ThreeFive MultiplesNot Completed

    Solutions: 2872 | View all user solutions | Challenge discussion

    Binary Search Tree LCANot Completed

    Solutions: 306 | View all user solutions | Challenge discussion

    Coin DeterminerNot Completed

    Solutions: 2339 | View all user solutions | Challenge discussion

    Fibonacci CheckerNot Completed

    Solutions: 2678 | View all user solutions | Challenge discussion

    Multiple BracketsNot Completed

    Solutions: 2393 | View all user solutions | Challenge discussion

    Most Free TimeNot Completed

    Solutions: 1452 | View all user solutions | Challenge discussion

    Overlapping RectanglesNot Completed

    Solutions: 1639 | View all user solutions | Challenge discussion

    Look Say SequenceNot Completed

    Solutions: 1505 | View all user solutions | Challenge discussion

    Distinct ListNot Completed

    Solutions: 2428 | View all user solutions | Challenge discussion

    Number EncodingNot Completed

    Solutions: 1512 | View all user solutions | Challenge discussion

    Stock PickerNot Completed

    Solutions: 764 | View all user solutions | Challenge discussion

    Max SubarrayNot Completed

    Solutions: 699 | View all user solutions | Challenge discussion

    Missing DigitNot Completed

    Solutions: 470 | View all user solutions | Challenge discussion

    K Unique CharactersNot Completed

    Solutions: 486 | View all user solutions | Challenge discussion

    Bitmap HolesNot Completed

    Solutions: 344 | View all user solutions | Challenge discussion

    Symmetric TreeNot Completed

    Solutions: 302 | View all user solutions | Challenge discussion

    Binary Tree LCANot Completed

    Solutions: 169 | View all user solutions | Challenge discussion

    LRU CacheNot Completed

    Solutions: 209 | View all user solutions | Challenge discussion

    Tree ConstructorNot Completed

    Solutions: 312 | View all user solutions | Challenge discussion

    Array Min JumpsNot Completed

    Solutions: 255 | View all user solutions | Challenge discussion

    Nearest Smaller ValuesNot Completed

    Solutions: 454 | View all user solutions | Challenge discussion

    Matrix SpiralNot Completed

    Solutions: 218 | View all user solutions | Challenge discussion

    Word SplitNot Completed

    Solutions: 393 | View all user solutions | Challenge discussion

    Pair SearchingNot Completed

    Solutions: 128 | View all user solutions | Challenge discussion

    Boggle SolverNot Completed

    Solutions: 109 | View all user solutions | Challenge discussion

    HTML ElementsNot Completed

    Solutions: 172 | View all user solutions | Challenge discussion

    Missing Digit IINot Completed

    Solutions: 162 | View all user solutions | Challenge discussion

    Palindromic SubstringNot Completed

    Solutions: 273 | View all user solutions | Challenge discussion

    Trapping WaterNot Completed

    Solutions: 167 | View all user solutions | Challenge discussion

    Matrix PathNot Completed

    Solutions: 87 | View all user solutions | Challenge discussion

    Seating StudentsNot Completed

    Solutions: 163 | View all user solutions | Challenge discussion

    Longest Matrix PathNot Completed

    Solutions: 78 | View all user solutions | Challenge discussion

    Min Window SubstringNot Completed

    Solutions: 170 | View all user solutions | Challenge discussion

    Matrix ChainsNot Completed

    Solutions: 70 | View all user solutions | Challenge discussion

    Histogram AreaNot Completed

    Solutions: 122 | View all user solutions | Challenge discussion

    Matching CharactersNot Completed

    Solutions: 196 | View all user solutions | Challenge discussion

    Ternary ConverterNot Completed

    Solutions: 98 | View all user solutions | Challenge discussion

    Linear CongruenceNot Completed

    Solutions: 59 | View all user solutions | Challenge discussion

    Formatted NumberNot Completed

    Solutions: 210 | View all user solutions | Challenge discussion

    Largest Row ColumnNot Completed

    Solutions: 57 | View all user solutions | Challenge discussion

    Eight QueensNot Completed

    Solutions: 1609 | View all user solutions | Challenge discussion

    Three PointsNot Completed

    Solutions: 144 | View all user solutions | Challenge discussion

    Character RemovalNot Completed

    Solutions: 156 | View all user solutions | Challenge discussion

    Simple PasswordNot Completed

    Solutions: 204 | View all user solutions | Challenge discussion

    Preorder TraversalNot Completed

    Solutions: 95 | View all user solutions | Challenge discussion

    String ZigzagNot Completed

    Solutions: 103 | View all user solutions | Challenge discussion

    Off BinaryNot Completed

    Solutions: 88 | View all user solutions | Challenge discussion

    Longest ConsecutiveNot Completed

    Solutions: 313 | View all user solutions | Challenge discussion

    String ExpressionNot Completed

    Solutions: 143 | View all user solutions | Challenge discussion

    Charlie the DogNot Completed

    Solutions: 91 | View all user solutions | Challenge discussion

    Plus MinusNot Completed

    Solutions: 134 | View all user solutions | Challenge discussion

    PrimesNot Completed

    Solutions: 73 | View all user solutions | Challenge discussion

    String CalculateNot Completed

    Solutions: 37 | View all user solutions | Challenge discussion

    Hard Difficulty

    Sudoku Quadrant CheckerNot Completed

    Solutions: 142 | View all user solutions | Challenge discussion

    Optimal AssignmentsNot Completed

    Solutions: 542 | View all user solutions | Challenge discussion

    Transitivity RelationsNot Completed

    Solutions: 419 | View all user solutions | Challenge discussion

    Shortest PathNot Completed

    Solutions: 1204 | View all user solutions | Challenge discussion

    Polynomial ExpansionNot Completed

    Solutions: 304 | View all user solutions | Challenge discussion

    CalculatorNot Completed

    Solutions: 1188 | View all user solutions | Challenge discussion

    Pattern ChaserNot Completed

    Solutions: 782 | View all user solutions | Challenge discussion

    Weighted PathNot Completed

    Solutions: 368 | View all user solutions | Challenge discussion

    RREF MatrixNot Completed

    Solutions: 134 | View all user solutions | Challenge discussion

    Intersecting LinesNot Completed

    Solutions: 582 | View all user solutions | Challenge discussion

    Kaprekars ConstantNot Completed

    Solutions: 6316 | View all user solutions | Challenge discussion

    Hamiltonian PathNot Completed

    Solutions: 152 | View all user solutions | Challenge discussion

    Step WalkingNot Completed

    Solutions: 118 | View all user solutions | Challenge discussion

    Gas StationNot Completed

    Solutions: 602 | View all user solutions | Challenge discussion

    Symmetric MatrixNot Completed

    Solutions: 416 | View all user solutions | Challenge discussion

    Switch SortNot Completed

    Solutions: 293 | View all user solutions | Challenge discussion

    Matrix DeterminantNot Completed

    Solutions: 272 | View all user solutions | Challenge discussion

    Queen CheckNot Completed

    Solutions: 482 | View all user solutions | Challenge discussion

    Noughts DeterminerNot Completed

    Solutions: 384 | View all user solutions | Challenge discussion

    Blackjack HighestNot Completed

    Solutions: 554 | View all user solutions | Challenge discussion

    Alphabet Run EncryptionNot Completed

    Solutions: 251 | View all user solutions | Challenge discussion

    Vertex CoveringNot Completed

    Solutions: 148 | View all user solutions | Challenge discussion

    Knight JumpsNot Completed

    Solutions: 528 | View all user solutions | Challenge discussion

    Farthest NodesNot Completed

    Solutions: 158 | View all user solutions | Challenge discussion

    Line OrderingNot Completed

    Solutions: 74 | View all user solutions | Challenge discussion

    Quick KnightNot Completed

    Solutions: 69 | View all user solutions | Challenge discussion

    Square FiguresNot Completed

    Solutions: 161 | View all user solutions | Challenge discussion

    Connect Four WinnerNot Completed

    Solutions: 110 | View all user solutions | Challenge discussion

    Array JumpingNot Completed

    Solutions: 87 | View all user solutions | Challenge discussion

    Matrix BorderNot Completed

    Solutions: 83 | View all user solutions | Challenge discussion

    Roman Numeral ReductionNot Completed

    Solutions: 107 | View all user solutions | Challenge discussion

    Parallel SumsNot Completed

    Solutions: 169 | View all user solutions | Challenge discussion

    LCSNot Completed

    Solutions: 99 | View all user solutions | Challenge discussion

    Nim WinnerNot Completed

    Solutions: 60 | View all user solutions | Challenge discussion

    Pascals TriangleNot Completed

    Solutions: 119 | View all user solutions | Challenge discussion

    Reverse Polish NotationNot Completed

    Solutions: 225 | View all user solutions | Challenge discussion

    Max Heap CheckerNot Completed

    Solutions: 108 | View all user solutions | Challenge discussion

    Chessboard TravelingNot Completed

    Solutions: 2750 | View all user solutions | Challenge discussion

    Matching CouplesNot Completed

    Solutions: 127 | View all user solutions | Challenge discussion

    Approaching FibonacciNot Completed

    Solutions: 154 | View all user solutions | Challenge discussion

    Simple SATNot Completed

    Solutions: 82 | View all user solutions | Challenge discussion

    Array CouplesNot Completed

    Solutions: 124 | View all user solutions | Challenge discussion

    Bracket CombinationsNot Completed

    Solutions: 142 | View all user solutions | Challenge discussion

    Counting AnagramsNot Completed

    Solutions: 185 | View all user solutions | Challenge discussion

    Array RotationNot Completed

    Solutions: 201 | View all user solutions | Challenge discussion

    Maximal SquareNot Completed

    Solutions: 1939 | View all user solutions | Challenge discussion

    Maximal RectangleNot Completed

    Solutions: 50 | View all user solutions | Challenge discussion

    Bipartite MatchingNot Completed

    Solutions: 49 | View all user solutions | Challenge discussion

    Pentagonal NumberNot Completed

    Solutions: 2037 | View all user solutions | Challenge discussion

    City TrafficNot Completed

    Solutions: 51 | View all user solutions | Challenge discussion

    Convex Hull PointsNot Completed

    Solutions: 34 | View all user solutions | Challenge discussion

    Wildcard CharactersNot Completed

    Solutions: 85 | View all user solutions | Challenge discussion

    Tetris MoveNot Completed

    Solutions: 41 | View all user solutions | Challenge discussion

    WildcardsNot Completed

    Solutions: 43 | View all user solutions | Challenge discussion

    Difficulty

    Companies

    • Google 44
    • Facebook 23
    • Microsoft 21
    • Amazon 12

    Bootcamps

    • Hack Reactor 87
    • Fullstack Academy 87
    • Grace Hopper 87
    • App Academy 87
    • Codesmith 87

    All Tags

    • searching 102
    • array 71
    • string manipulation 64
    • math fundamentals 58
    • hash table 23
    • optimization 22
    • matrix 21
    • dynamic programming 20
    • recursion 13
    • regular expression 13
    • game 10
    • algebra 10
    • graph 9
    • combinatorics 9
    • sorting 8
    • sequences 7
    • stack 7
    • encoding 6
    • chess 5
    • binary tree 5
    • geometry 4
    • linear algebra 4
    • prime numbers 4
    • set theory 3
    • heap 3
    • bitwise operation 2
    • cache 1