算法課的作業，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 = 100arrayInt = Array.newfor index in (0..12) arrayInt[index] = rand(100) #produce 12 random numberendputs "The original array is：" + arrayInt.to_sdef 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) endenddef 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) endendmerge_sort(arrayInt, 0, arrayInt.length-1)puts "The sorted array is: " + arrayInt.to_s