kimyoutora

>> Version
=> "0.8.2"
>> MongoMapper::Version
=> "0.8.2"

kimyoutora

require 'chronic_duration'

ps0=Post.all(:conditions => ["? <= created_at and created_at <= ? ", Time.parse("06/29/2010"), Time.parse("07/05/2010")], :include => :replies)

ps1=Post.all(:conditions => ["? <= created_at and created_at <= ? ", Time.parse("07/06/2010"), Time.parse("07/12/2010")], :include => :replies)

ps2=Post.all(:conditions => ["? <= created_at and created_at <= ? ", Time.parse("07/13/2010"), Time.parse("07/19/2010")], :include => :replies)

ps3=Post.all(:conditions => ["? <= created_at and created_at <= ? ", Time.parse("07/20/2010"), Time.parse("07/26/2010")], :include => :replies)

kimyoutora

# randomly shuffle cards in-place
# Fisher-Yates Shuffle
# Use the back of the array for storing the
# randomly picked card and move your way to the front
class Array
  def shuffle
    length = self.size
    array = self.dup

    (length - 1).step(0, -1).each do |i|

kimyoutora

# Partition-based selection algorithm to find the
# median of an array in O(N) time
# Note that this is very similar to quicksort but since
# we know which partition our element lies in, we are reducing
# the problem space by 1/2 at every step on average and thus,
# N + 1/2 x N + 1/4 x N + 1/8 x N + ...
# This sequence leads to N x (sum of series from 1...1/inf) = 
# N x (1 + 1) = 2N = O(N) running time
class Array
  def median

kimyoutora

def sqrt(num, precision, beg=0, final=num)
  final = 1 if num < 1 # handle cases where the squareroot is > num i.e. sqrt(0.1) ~ 0.3

  begin
    guess = (beg + final) / 2.0
    diff = num - (guess ** 2)

    if diff.abs <= precision
      return guess
    elsif diff > 0

kimyoutora

def occurrences(sorted_array)
  puts "occurrences: #{sorted_array.inspect}"
  count = 0

  sorted_array.each_with_index do |num, index|
    if index + 1 >= sorted_array.size || num != sorted_array[index+1]
      puts "#{num}: #{count+1}"
      count = 0
    else
      count += 1

kimyoutora

def fib(n)
  cache = {}

  n.times do |i|
    if i == 0
      cache[0] = 0
    elsif i == 1
      cache[1] = 1
    else
      cache[i] = cache[i-1] + cache[i-2]

kimyoutora

THOUSANDS = ['', 'thousand', 'million', 'billion']
NUMS = {
  "0"   => '',
  "1"   => 'one',
  "2"   => 'two',
  "3"   => 'three',
  "4"   => 'four',
  "5"   => 'five',
  "6"   => 'six',
  "7"   => 'seven',

kimyoutora

# my attempt
def powerset(set)
  all_sets = [[]]
  set.each do |elem|
    subsets = []
    all_sets.each do |subset|
      subsets << subset + [elem]
    end
    all_sets += subsets
  end

kimyoutora

class BitMaskNode
  attr_accessor :children, :name
  attr_reader :mask

  def initialize(name, bitmask)
    @name = name
    @mask = bitmask
    @children = []
  end