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Copy pathMergeSort.py
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70 lines (61 loc) · 1.71 KB
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import numpy as np
def __merge(arr,start,mid,end):
aux = arr[start:end+1]
i = start
j = mid + 1
k = start
while k <= end:
if i > mid:
arr[k] = aux[j-start]
j += 1
elif j > end:
arr[k] = aux[i-start]
i += 1
elif aux[i - start] < aux[j - start]:
arr[k] = aux[i-start]
i += 1
else :
arr[k] = aux[j-start]
j += 1
k += 1
#注意千万注意优先判断数组越界，否则报错像下面一样。
# for k in range(end - start + 1 ):
# if (j > end or aux[i - start] < aux[j - start]):
# arr[k+start] = aux[i-start]
# i += 1
# elif (i > mid or aux[i - start] > aux[j - start] ):
# arr[k+start] = aux[j-start]
# j += 1
# else:
# return
def __mergeSort(arr,start,end):
if start >= end:
return
#这里mid注意下
mid = int((end + start)/2)
__mergeSort(arr, start, mid)
__mergeSort(arr, mid+1, end)
__merge(arr, start, mid, end)
def mergeSort(arr):
__mergeSort(arr, 0, len(arr)-1)
# def MergeSort(arr):
# length = len(arr)
# if length>1:
# half = int(length/2)
# left_arr = arr[0:half-1]
# right_arr = arr[half:length-1]
# MergeSort(left_arr)
# MergeSort(right_arr)
# j = half
# i = 0
# for k in range(length):
# if i < half and j < length:
# if left_arr[i] > right_arr[j]:
# arr[k] = right_arr[j]
# j += 1
# else:
# arr[k] = left_arr[i]
# i += 1
#
#
# return arr