Java Puzzle Utils

Various utilities, data structures, and algorithms written in Java for solving coding puzzles like Advent of Code.

Compatibility: Java 21+

However, Java is not the best language for coding puzzles. Consider using Kotlin instead. :)

Cheat sheet

This section lists a few notable utilities of the JDK and the Guava library, which can be practical for solving coding puzzles (besides the tools provided in this library).

JDK

• Language features
  • lambdas
  • var (Java 11+)
  • records (Java 14+)
  • switch expressions (Java 14+)
• Collections
  • sequenced collections: first/last element and reversed view (Java 21+)
  • List.of(), Set.of(), Map.of()
  • LinkedHashSet, LinkedHashMap
  • NavigableSet (e.g. TreeSet)
  • Collections.rotate(List, int)
• Streams
  • stream API
  • Stream::toList (Java 16+)
• Other
  • Math.clamp, Math.floorDiv, Math.floorMod
  • Arrays.mismatch()

Guava

• Ints, Longs, etc. - utils for (arrays of) primitives
• Lists
  • partition(List, int)
  • cartesianProduct(List...)
• Sets
  • intersection(Set, Set), union(Set, Set)
  • difference(Set, Set), symmetricDifference(Set, Set)
  • combinations(Set, int), powerSet(Set)
  • cartesianProduct(Set...)
• Multisets, multimaps
  • Multiset, HashMultiset, LinkedHashMultiset, TreeMultiset
  • Multimap, MultimapBuilder, e.g.:
    • MultimapBuilder.hashKeys().arrayListValues().build()
    • MultimapBuilder.linkedHashKeys().hashSetValues().build()
  • Multimaps, Multisets - related utils (collectors, filtering, etc.)
• Other
  • BiMap, HashBiMap
  • Range
  • RangeSet
  • Table, HashedBasedTable, TreeBasedTable
• LongMath (or IntMath)
  • gcd(long, long) - greatest common divisor
  • binomial(int, int)
  • factorial(int)
  • isPrime(long)
  • isPowerOfTwo(long)