davepkennedy

-module(euler1).
-export([sum/1]).

sum(0) -> 0;
sum(X) when X rem 3 == 0 -> X + sum(X-1);
sum(X) when X rem 5 == 0 -> X + sum(X-1);
sum(X) -> sum(X-1).

davepkennedy

  <build>
    <plugins>
      <plugin>
        <groupId>org.mortbay.jetty</groupId>
        <artifactId>maven-jetty-plugin</artifactId>

        <version>6.1.26</version>
        <configuration>
          <scanIntervalSeconds>10</scanIntervalSeconds>
          <stopKey>foo</stopKey>

davepkennedy

object heapsort {
  def left(i: Int) = (2*i) + 1                    //> left: (i: Int)Int
  def right(i: Int) = left(i) + 1                 //> right: (i: Int)Int
  def parent(i: Int) = (i - 1) / 2                //> parent: (i: Int)Int

	def swap(a: Array[Int], i: Int, j: Int): Unit = {
		val t = a(i)
		a(i) = a(j)
		a(j) = t
	}                                         //> swap: (a: Array[Int], i: Int, j: Int)Unit

davepkennedy

object numbertext {
	val singleDigits = Array("zero", "one","two","three","four","five","six","seven","eight","nine")
                                                  //> singleDigits  : Array[String] = Array(zero, one, two, three, four, five, six
                                                  //| , seven, eight, nine)
	val teens = Array("ten","eleven","twelve","thirteen","fourteen","fifteen","sixteen","seventeen","eighteen","nineteen")
                                                  //> teens  : Array[String] = Array(ten, eleven, twelve, thirteen, fourteen, fift
                                                  //| een, sixteen, seventeen, eighteen, nineteen)
	val tens = Array ("","","twenty","thirty","fourty","fifty","sixty","seventy","eighty","ninety")
                                                  //> tens  : Array[String] = Array("", "", twenty, thirty, fourty, fifty, sixty, 
                                                  //| seventy, eighty, ninety)

davepkennedy

object permutations {
	def insertAt[T](e: T, p: Int, l: List[T]): List[T] = p match {
		case 0 => e :: l
		case _ => l.head :: insertAt(e, p-1, l.tail)
	}                                         //> insertAt: [T](e: T, p: Int, l: List[T])List[T]

	def permute[T] (l: List[T]): List[List[T]] = l match {
		case Nil => Nil
		case h :: t =>
			println(h, t)

davepkennedy

Latency Comparison Numbers
--------------------------
L1 cache reference                            0.5 ns
Branch mispredict                             5   ns
L2 cache reference                            7   ns             14x L1 cache
Mutex lock/unlock                            25   ns
Main memory reference                       100   ns             20x L2 cache, 200x L1 cache
Compress 1K bytes with Zippy              3,000   ns
Send 1K bytes over 1 Gbps network        10,000   ns    0.01 ms
Read 4K randomly from SSD*              150,000   ns    0.15 ms

davepkennedy

def fib (count: Int): Int = {
  @tailrec def _fib (count: Int, value: Int, accum: Int = 0): Int = count match {
    case 0 => accum
    case _ => _fib(count - 1, accum, value + accum)
  }
  _fib(count, 1)
}

davepkennedy

def add (a: Int, b: Int): Int = {
  @tailrec
  def helper (c: Int, d: Int): Int = d match {
    case 0 => c
    case _ => helper (c ^ d, (c & d) << 1)
  }
  helper(a, b)
}

davepkennedy

public class App 
{
    private static final String JDBC_DRIVER = "org.sqlite.JDBC";
    private static final String CONNECTION_STRING = "jdbc:sqlite:/tmp/testdb.db";
    public static void main( String[] args ) throws SQLException, ClassNotFoundException {

        SQLiteDataSource ds = new SQLiteDataSource();
        ds.setUrl("jdbc:sqlite:/tmp/data.db");
        DBI dbi = new DBI(ds);
        Handle h = dbi.open();

davepkennedy

def search [T <% Ordered[T]] (s: Seq[T], elem: T): Boolean = {
  var low = 0
  var high = s.length - 1
  while (low <= high) {
    val mid = (low + high) / 2
    if (s(mid) == elem) {return true}
    if (elem < s(mid)) {high = mid-1}
    if (elem > s(mid)) {low = mid+1}
  }
  false