算法导论笔记1 - 插入排序 vs 归并排序

import random
import time

__author__ = ‘Administrator‘

LENGTH = 3000
base = []

for i in range(0, LENGTH):
    base.append(random.randint(0, LENGTH))


def ins_sort(array):
    for border in range(1, len(array)):
        j = border - 1
        key = array[border]
        while j >= 0 and array[j] > key:
            array[j + 1] = array[j]
            j -= 1
        array[j + 1] = key


def merge_sort(array):

    def split(arr):
        return arr[0: int(len(arr) / 2)], arr[int(len(arr) / 2):]

    res = []
    k_a = k_b = 0
    part_a, part_b = split(array)
    if len(part_a) is not 1:
        part_a = merge_sort(part_a)
    if len(part_b) is not 1:
        part_b = merge_sort(part_b)
    while k_a < len(part_a) and k_b < len(part_b):
        if part_a[k_a] < part_b[k_b]:
            res.append(part_a[k_a])
            k_a += 1
        else:
            res.append(part_b[k_b])
            k_b += 1
    if k_a < len(part_a):
        res.extend(part_a[k_a:])
    else:
        res.extend(part_b[k_b:])
    return res

print("=======")
print(base)
pre = time.time()
result = base.copy()
ins_sort(result)
print("insertion:" + str(time.time() - pre))
print(result)

print("=======")
print(base)
pre = time.time()
result = merge_sort(base)
print("merge:" + str(time.time() - pre))
print(result)