python算法学习之桶排序算法实例(分块排序)
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2020-12-25
08:03:38
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python算法学习之桶排序算法实例算法学习之桶排序算法实例(分块排序分块排序)
复制代码 代码如下:
# -*- coding: utf-8 -*-
def insertion_sort(A):
“””插入排序，作为桶排序的子排序”””
n = len(A)
if n <= 1:
return A
B = [] # 结果列表
for a in A:
i = len(B)
while i > 0 and B[i-1] > a:
i = i – 1
B.insert(i, a);
return B
def bucket_sort(A):
“””桶排序，伪码如下：
BUCKET-SORT(A)
1 n ← length[A] // 桶数
2 for i ← 1 to n
3 do insert A[i] into list B[floor(nA[i])] // 将n个数分布到各个桶中
4 for i ← 0 to n-1
5 do sort list B[i] with insertion sort // 对各个桶中的数进行排序
6 concatenate the lists B[0],B[1],…,B[n-1] together in order // 依次串联各桶中的元素
桶排序假设输入由一个随机过程产生，该过程将元素均匀地分布在区间[0,1)上。
“””
n = len(A)
buckets = [[] for _ in xrange(n)] # n个空桶
for a in A:
buckets[int(n * a)].append(a)
B = []
for b in buckets:
B.extend(insertion_sort(b))
return B
if __name__ == ‘__main__’:
from random import random
from timeit import Timer
items = [random() for _ in xrange(10000)]
def test_sorted():
print(items)
sorted_items = sorted(items)
print(sorted_items)
def test_bucket_sort():
print(items)
sorted_items = bucket_sort(items)
print(sorted_items)
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