Ruby实现的合并排序算法

算法课的作业，利用分治法，合并排序。

#encoding: utf-8
#author: xu jin, 4100213
#date: Oct 27, 2012
#MergeSort
#to sort an array by using MergeSort algorithm
#example output:
#The original array is：[4, 32, 84, 58, 49, 40, 75, 29, 82, 21, 70, 37, 70]
#The sorted array is: [4, 21, 29, 32, 37, 40, 49, 58, 70, 70, 75, 82, 84]
MAX = 100
arrayInt = Array.new
for index in (0..12)
arrayInt[index] = rand(100) #produce 12 random number
end
puts "The original array is：" + arrayInt.to_s
def merge(arr, left, middle, right)
arrL ,arrR = Array.new, Array.new
arrL[0..(middle - left)], arrR[0..(right - middle - 1)] = arr[left..middle], arr[middle + 1.. right]
arrL[arrL.size] ,arrR[arrR.size]= MAX, MAX
for k in (left..right)
arrL.first <= arrR.first ? (arr[k] = arrL.shift) : (arr[k] = arrR.shift)
end
end
def merge_sort(arr, left, right)
if left < right then
middle = (left + right)/2
merge_sort(arr, left, middle)
merge_sort(arr, middle + 1, right)
merge(arr, left, middle, right)
end
end
merge_sort(arrayInt, 0, arrayInt.length-1)
puts "The sorted array is: " + arrayInt.to_s

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