Problem 24 (Level 1!!!)

21-30/023.rb

@@ -43,7 +43,8 @@
   end
 end
 
-# Our filter is ready (with all abundant numbers set to 1), just sum them all!
+# Our filter is ready (with all the numbers that are sums of abundant numbers set to 1), 
+# just sum them all!
 sum_abundants=0
 (1..n).each do |pos|
   sum_abundants+=pos if abundant_nums_filter[pos] == 1

21-30/024.rb

@@ -0,0 +1,32 @@
+#!/usr/bin/env ruby -w
+
+require_relative '../Utils/MathUtils'
+include MathUtils
+
+# Based on the course notes of the University of Exeter's Computational Physics class (PHY3134)
+
+values=[0,1,2,3,4,5,6,7,8,9]
+$result=[]
+
+
+def permute(values,start,n)
+  if start == n-1
+    $result << values.join 
+  else  
+    (start...n).each do |pos|
+      tmp = values[pos]
+
+      values[pos] = values[start]
+      values[start] = tmp
+
+      permute(values,start+1,n)
+
+      values[start] = values[pos]
+      values[pos] = tmp
+    end  
+  end
+end  
+
+permute(values,0,values.size)
+# Because the array starts at 0
+$result.sort[999999]