I am using Feedzirra in one of my projects. I was trying to experiment my app with Rails3 and found the following issue when using Feedzirra. This is just a hack to get it to work, I am sure there are better ways to solve it. The issue is Feedzirra uses Loofah library for html scrubbing. Loofah makes some assumptions about the Rails framework as in code on line# 86 here
if defined? Rails.configuration and Rails.configuration.frameworks.include?([:active_record]) # rails 2.1 and later
Rails.configuration.after_initialize do
require 'loofah/active_record'
require 'loofah/xss_foliate'
end
elsif defined? ActiveRecord::Base # rails 2.0
require 'loofah/active_record'
require 'loofah/xss_foliate'
end
As per new changes in Rails3 (framework agnostic), config.frameworks is deprecated causing the following error config.frameworks in no longer supported. See the generated config/boot.rb for steps on how to limit the frameworks that will be loaded (RuntimeError).
To get around this I have made the following change
loofah.rb line# 86
begin
if defined? ActiveRecord::Base
require 'loofah/active_record'
require 'loofah/xss_foliate'
elsif defined? Rails.configuration and Rails.configuration.frameworks.include?([:active_record]) # rails 2.1 and later
Rails.configuration.after_initialize do
require 'loofah/active_record'
require 'loofah/xss_foliate'
end
end
rescue
#handle the error accordingly
end
Add new gem group to Gemfile of rails3 app
group :after_initialize do
gem "feedzirra", :git => "git://github.com/chrismsnz/feedzirra.git"
end
Now tell Bundler to load feedzirra after application initializtion by changing application.rb of rails3 app like this
Bundler.require :after_initialize
BTW I used the forked Feedzirra branch of chrismsnz available here instead of original pauldix tree.
Hope this helps someone.
Problem:
Calculate the sum of all the primes below two million (2000000)
import scala.collection.mutable.ListBuffer
import scala.collection.mutable.Map
object Problem10 {
def main(args: Array[String]) :Unit = {
println(findSumOfPrimesFast(2000000))
}
def findSumOfPrimesFast(max: Int) : BigInt = {
//initialize sum to basic primes
var sum = BigInt(0)
if(max > 2) sum += 2
if(max > 3) sum += 3
if(max > 5) sum += 5
if(max > 7) sum += 7
if(max > 11) sum += 11
//initialize map with numbers < max and not multiples of basic primes
var map = Map[Int, Boolean]()
for {
i <- 2.until(max)
if(i % 2 != 0)
if(i % 3 != 0)
if(i % 5 != 0)
if(i % 7 != 0)
if(i % 11 != 0)
} map += (i -> true)
var i = 13
while(i <= Math.sqrt(max)) {
if(map.contains(i)) {
map -- multiples(i, max)
sum += i
}
i += 2 //skipping evens
}
//all numbers greater than sqrt(max) are primes
val iter = map.keys
while(iter.hasNext) {
sum += iter.next
}
return sum
}
def multiples(number:Int, max:Int) : Iterable[Int] = {
val numbers = new ListBuffer[Int]()
var multiple = number
var loop = 1;
while(multiple < max) {
numbers += multiple
loop += 1
multiple = number * loop
}
return numbers
}
}
Problem:
Find the only Pythagorean triplet, {a, b, c}, for which a + b + c = 1000.
object Problem9 {
def main(args: Array[String]) :Unit = {
val list = findPythagoreanTriplets(1000)
val product = list.first._1 * list.first._2 * list.first._3
println(product)
}
def findPythagoreanTriplets(number:Int) : List[Tuple3[Int, Int, Int]] = {
for{ a <- 1.to(number - 1)
b <- (a+1).to(number)
c = number - a - b
if(a*a + b*b == c*c)
} return List((a,b,c))
return List()
}
}
Problem:
Discover the largest product of five consecutive digits in the 1000-digit number.
object Problem8 {
def main(args: Array[String]) :Unit = {
println(solve(numberStr))
}
val numberStr = "7316717653133062491922511967442657474235534919493496983520312774506326239578318016984801869478851843858615607891129494954595017379583319528532088055111254069874715852386305071569329096329522744304355766896648950445244523161731856403098711121722383113622298934233803081353362766142828064444866452387493035890729629049156044077239071381051585930796086670172427121883998797908792274921901699720888093776657273330010533678812202354218097512545405947522435258490771167055601360483958644670632441572215539753697817977846174064955149290862569321978468622482839722413756570560574902614079729686524145351004748216637048440319989000889524345065854122758866688116427171479924442928230863465674813919123162824586178664583591245665294765456828489128831426076900422421902267105562632111110937054421750694165896040807198403850962455444362981230987879927244284909188845801561660979191338754992005240636899125607176060588611646710940507754100225698315520005593572972571636269561882670428252483600823257530420752963450"
def solve(number:String) : Int = {
val number1 = number
val number2 = number1.substring(1);
val number3 = number2.substring(1);
val number4 = number3.substring(1);
val number5 = number4.substring(1);
var max = 0
var i = 0
while(i < numberStr.length - 5)
{
val n1 = Integer.parseInt(number1(i).toString)
val n2 = Integer.parseInt(number2(i).toString)
val n3 = Integer.parseInt(number3(i).toString)
val n4 = Integer.parseInt(number4(i).toString)
val n5 = Integer.parseInt(number5(i).toString)
val product = n1 * n2 * n3 * n4 * n5
if(product == Math.pow(9, 5)) return product
if(product > max) {
println(n1 + "," + n2 + "," + n3 + "," + n4 + "," + n5)
max = product
}
i += 1
}
return max
}
}
Problem:
Find the 10001st prime.
object Problem7 {
def main(args: Array[String]) :Unit = {
println(findNthPrime(10001))
}
def findNthPrime(n:Int) : Long = {
var primeSet = List[Long](2L)
var number = 3L
while(primeSet.size < n)
{
if(isPrime(primeSet, number)) primeSet = number :: primeSet
number += 1
}
return primeSet.first
}
def isPrime(primeSet:Seq[Long], n:Long) : Boolean = {
for( i <- primeSet ) {
if(n % i == 0) return false
}
return true
}
}
Problem:
What is the difference between the sum of the squares and the square of the sums?
object Problem6 {
def main(args: Array[String]) :Unit = {
println(solve(100))
}
def solve(number:Int) : Int = {
var sum = 0
for {
i <- 1.to(number-1)
j <- (i+1).to(number)
} sum += 2 * i * j
return sum
}
}
Problem:
What is the smallest number divisible by each of the numbers 1 to 20?
object Problem5 {
def main(args : Array[String]) : Unit = {
println(solve(20))
}
def solve(number:Int) : Long = {
var lcm = 1L
for( i <- 2.to(number); if(isPrime(i))) {
val multiplesOfI = countPowersOfN(i, number)
lcm *= power(i, multiplesOfI)
}
return lcm
}
def power(n:Int, m:Int) : Long = {
var pow = 1
for( i <- 1.to(m)) pow = pow * n
return pow
}
def isPrime(number:Int) : Boolean = {
for {
n <- 2.to(Math.sqrt(number))
} if (number % n == 0) return false
return true
}
def countPowersOfN(n:Int, number:Int) : Int = {
if(n < 2) throw new IllegalArgumentException("n should be >= 2")
if(number < n) return 0
return 1 + countPowersOfN(n, number/n)
}
}
Problem
Find the largest palindrome made from the product of two 3-digit numbers.
object Problem4 {
def main(args : Array[String]) : Unit = {
println(solve(3))
}
def solve(nDigits:Int) : Int = {
val start = Math.pow(10, nDigits).intValue - 1
val end = Math.pow(10, nDigits-1).intValue - 1
val nDigitNumbers = new Range(start, end, -1)
val productPalindromes = for{
n1 <- nDigitNumbers
n2 <- nDigitNumbers
prod = (n1 * n2)
if(isPalindrome(prod))
} yield prod
productPalindromes.reduceLeft(max(_,_))
}
def max(x:Int, y:Int) : Int = if(x > y) x else y
def isPalindrome(x:Int) : Boolean = {
val str = x.toString()
str == str.reverse.toString()
}
}
Problem:
Find the largest prime factor of a composite number.
def main(args : Array[String]) : Unit = {
println(maxPrimeFactor(BigInt("600851475143")))
}
def maxPrimeFactor(number:BigInt) : BigInt = {
var max = BigInt(1)
var lowDivisor = BigInt(1)
var highDivisor = number
while(highDivisor >= lowDivisor) {
if(number % highDivisor == 0)
if(highDivisor.isProbablePrime(10)) return maxBigInt(max, highDivisor)
else if(lowDivisor.isProbablePrime(10)) max = maxBigInt(max, lowDivisor)
lowDivisor += 1
highDivisor = number/lowDivisor
}
if(max > 1) max else number
}
def maxBigInt(x:BigInt, y:BigInt) = if(x > y) x else y
Problem 2:
Find the sum of all the even-valued terms in the Fibonacci sequence which do not exceed four million.
object Problem2 {
def main(args : Array[String]) : Unit = {
val max = 4000000
val sum = sumOfFibNumbers(max, isEven, 0, 1, 0)
println(sum)
}
def isEven(x:Int) : Boolean = x % 2 == 0
def sumOfFibNumbers(max:Int, p:(Int => Boolean), n1:Int, n2:Int, sum:Int): Int = {
if(n1 < max) {
if(p(n1)) sumOfFibNumbers(max, p, n2, n1+n2, sum + n1)
else sumOfFibNumbers(max, p, n2, n1+n2, sum)
}
else sum
}
}