update ruby version code

Author: Ronghai Wei

ebook/code/ruby/chapter04.rb

@@ -21,6 +21,7 @@ def o_index(sub)
   #Ruby 1.9 maintains hash order 
   #For Ruby 1.8 find orderedhash http://rubygems.org/gems/orderedhash
   #find first letter who's count is count
+  #This supports UTF-8
   def o_first_count_letter(count = 1)
     hash = Hash.new(0)
     each_char{|c|

ebook/code/ruby/chapter05.rb ebook/code/ruby/chapter05.findSum.rb

@@ -49,9 +49,9 @@ def find_sum_with_two(array, sum)
   print "find_03  ", array.find_03(sum), "\n"
 
   Benchmark.bm(10) do |x|
-    x.report("find_01:")   { 10000.times{ array.find_01(sum) } }
-    x.report("find_02:")   { 10000.times{ array.find_02(sum) } }
-    x.report("find_03:")   { 10000.times{ array.find_03(sum) } }
+    x.report("find_01:") { 10000.times{ array.find_01(sum) } }
+    x.report("find_02:") { 10000.times{ array.find_02(sum) } }
+    x.report("find_03:") { 10000.times{ array.find_03(sum) } }
   end
 end
 

ebook/code/ruby/chapter06.amicableNumber.rb

@@ -1,23 +1,25 @@
 #!/usr/bin/env ruby
 # -*- coding: UTF-8 -*-
 
-
- 
-
-if __FILE__ == $0
-  max = 5000000
-  half = (max**0.5).to_int
+def amicable_number max
+  half = max / 2 
   sum = Array.new(max){1}
   (2...half).each do|i|
     (i + i).step(max + 1, i)do|j|
-     sum[j] += i unless sum[j].nil?
+      sum[j] += i unless sum[j].nil?
     end
   end
-  
-  
-  
+  ans = []
   sum.each_with_index do | s, i|
-    p "%d %d" % [i, s] if s > i && s <= max && sum[s] == i
-  end
+   ans.push([i, s]) if s > i && s <= max && sum[s] == i
+  end 
+  ans
 end
 
+
+
+if __FILE__ == $0
+  amicable_number( 500000 ).each{|e|
+    p "%d %d" % e
+  }
+end

ebook/code/ruby/chapter07.findMaxSum.rb

@@ -14,24 +14,20 @@ def max_sum(arr)
   [max, max_sub]
 end
 
-def max(*ar)
-  return ar.max
-end
-
-def max_sum_2(arr)
+def max_sum_dp(arr)
   sum = Array.new(arr.length){0}
   sum[0] = arr[0]
   1.upto(arr.length - 1){|i|
-    sum[i] = max( arr[i], sum[i-1] + arr[i]) 
+    sum[i] = [ arr[i], sum[i-1] + arr[i]].max
   }
   sum.max
 end
 
 
 if __FILE__ == $0
-  p max_sum([-1,-2,-3,-4])
-  p max_sum([1, -2, 3, 10, -4, 7, 2, -5]) 
 
-  p max_sum_2([-1,-2,-3,-4])
-  p max_sum_2([1, -2, 3, 10, -4, 7, 2, -5]) 
+  [ [-1,-2,-3,-4] , [1, -2, 3, 10, -4, 7, 2, -5] ] .each{ |ar|
+    p ar, max_sum(ar), max_sum_dp(ar)  
+  }
+ 
 end

ebook/code/ruby/chapter16.permutation.rb

@@ -0,0 +1,27 @@
+#!/usr/bin/env ruby
+# -*- coding: UTF-8 -*-
+def permutation_recursive(ar)
+  return [ar] if ar.length == 1
+  permutations = []
+  ar.each_with_index{|a, i|
+    arc = ar.clone; arc.delete_at(i)
+    subpermutations = permutation_recursive(arc)
+    subpermutations.each{|x|
+      permutations.push( [a] + x)
+    }
+  }
+  
+  return permutations
+end
+
+
+if __FILE__ == $0
+  test_cases = [["A", "B", "C"]]
+  test_cases.each{|tc|
+    permutations = permutation_recursive(tc)
+    p "permutation", permutations, permutations.sort == tc.permutation(tc.length).sort
+  }
+  
+
+
+end

ebook/code/ruby/chapter17.rb

@@ -0,0 +1,15 @@
+#!/usr/bin/env ruby
+# -*- coding: UTF-8 -*-
+
+def fibonacci_solution n
+  return [0, 1, 2][n] if( n <= 2 )
+  fibonacci_solution(n - 1) +  fibonacci_solution( n - 2)
+end
+ 
+if __FILE__ == $0
+  steps = [1, 2, 3, 4, 5, 6]
+  p steps.map{|x|
+    [x, fibonacci_solution(x)]
+  }
+
+end

ebook/code/ruby/chapter18.rb

@@ -0,0 +1,28 @@
+#!/usr/bin/env ruby
+# -*- coding: UTF-8 -*-
+
+def odd_even(arr)
+  return arr.select{|x| x % 2 != 0 } +  arr.select{|x| x % 2 == 0 } 
+end
+
+def reorder_odd_even(arr)
+  si, ei = 0, arr.length - 1
+  while si < ei
+    if(arr[si].odd?)
+      si += 1; next
+    end
+    if(arr[ei].even?)
+      ei -= 1; next
+    end 
+    arr[si], arr[ei] = arr[ei], arr[si]
+  end
+  arr
+end
+
+if __FILE__ == $0
+  test_cases = [ [2, 1, 3, 4, 6, 5, 7] ]
+  test_cases.each{|tc|
+    p odd_even(tc), reorder_odd_even(tc)
+  }
+  
+end

ebook/code/ruby/chapter19.rb

@@ -0,0 +1,4 @@
+#!/usr/bin/env ruby
+# -*- coding: UTF-8 -*-
+# see 'chapter04.rb'
+# String.o_first_count_letter