python中归并排序

 # coding=UTF-8
 #!/usr/bin/python

 import sys

 def merge(nums, first, middle, last):
     "merge"
     #切片边界，左闭右开，从0开始
     lnums = nums[ first:middle+1 ]
     rnums = nums[ middle+1:last+1 ]
     lnums.append(sys.maxint)
     rnums.append(sys.maxint)
     l = 0
     r = 0
     for i in range( first, last+1 ):
         if lnums[l] < rnums[r]:
             nums[i] = lnums[l]
             l+=1
         else:
             nums[i] = rnums[r]
             r+=1

 def merge_sort(nums, first, last):
     """mergesort
         mergesort函数中传递的是下标，不是元素的个数
     """     if first < last:
         middle = (first + last)/2
         #print "middle in loop", count, "is:", middle
         merge_sort(nums, first, middle)
         merge_sort(nums, middle+1, last)
         merge(nums,first, middle, last)
         #print "loops:",count,">>", nums

 if __name__ == '__main__':
     nums = [10, 8, 4, -1, 2, 6, 7, 3]
     print "nums is ", nums
     merge_sort(nums, 0, 7)
     print "merge_sort", nums

/usr/bin/python2.7 /root/PycharmProjects/Sort/merge-sort.py
nums is  [10, 8, 4, -1, 2, 6, 7, 3]
merge_sort [-1, 2, 3, 4, 6, 7, 8, 10]

Process finished with exit code 0