examples/rosettacode/hailstone.nit

   1 # This file is part of NIT ( http://www.nitlanguage.org ).
   2 # This program is public domain
   3 # Copyright 2014 amineorion <amineorion@gmail.com>
   4 #
   5 # Licensed under the Apache License, Version 2.0 (the "License");
   6 # you may not use this file except in compliance with the License.
   7 # You may obtain a copy of the License at
   8 #
   9 #     http://www.apache.org/licenses/LICENSE-2.0
  10 #
  11 # Unless required by applicable law or agreed to in writing, software
  12 # distributed under the License is distributed on an "AS IS" BASIS,
  13 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14 # See the License for the specific language governing permissions and
  15 # limitations under the License.
  16 #
  17 # Task: Hailstone sequence
  18 # SEE: <http://rosettacode.org/wiki/Hailstone_sequence>
  19 #
  20 # Not optimize version.
  21
  22 module hailstone
  23
  24 fun hailstone (n: Int): Array[Int]
  25 do
  26         var sequence = [n]
  27         while n != 1 do
  28                 if n.bin_and(0x01) == 0 then
  29                         n = n / 2
  30                 else
  31                         n = 3 * n + 1
  32                 end
  33                 sequence.add(n)
  34         end
  35         return sequence
  36 end
  37 var sequence27 = hailstone(27)
  38 var size27 = sequence27.length
  39 print "Sequence for 27 has {size27} begin with: {sequence27[0]}, " +
  40                  "{sequence27[1]}, {sequence27[2]}, {sequence27[3]} " +
  41                  "and end with: {sequence27[size27 - 4]}, {sequence27[size27 - 3]}, " +
  42                  "{sequence27[size27 - 2]}, {sequence27[size27 - 1]}"
  43
  44 var max = hailstone(1).length
  45 var max_sequence = hailstone(1)
  46 var max_element = 1
  47
  48 for i in [2..100000] do
  49         var sequence = hailstone(i)
  50         if max < sequence.length then
  51                 max = sequence.length
  52                 max_element = i
  53                 max_sequence = sequence
  54         end
  55 end
  56 print "The number with longest sequence is {max_element} " +
  57                 "with length of {max_sequence.length}"