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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