排序（计数、希尔、基数）---python

#线性时间排序：时间复杂度为O(n)  计数排序，桶排序，基数排序

#计数排序
def count_sort(l,max_num = 100):
    count = [0 for _ in range(max_num + 1)]
    for val in l:
        count[val] += 1
    l.clear()
    for i, v in enumerate(count): #表示i这个数出现v次
        for _ in range(v):
            l.append(i)
    return l

l = [1,1,1,2,3,9,9,4,4,4,5,5]
print(count_sort(l))

#希尔排序是一种分组插入排序，每趟使整体数据越来越接近有序
def insert_sort_gap(l,d):
    for i in range(d,len(l)):
        tmp = l[i]
        j = i - d
        while j >= 0 and l[j] > tmp:
            l[j+d] = l[j]
            j -= d
        l[j+d] = tmp
def shell_sort(l):
    d = len(l)
    while d > 0:
        insert_sort_gap(l,d)
        d = d // 2
    return l

l = [3,4,5,2,7,34,11,23]
print(shell_sort(l))

#基数排序  （只能处理正整数）
def radix_sort(l):
    max_num = max(l)
    i = 0
    while (10**i <= max_num):
        buckets = [[] for _ in range(10)]
        for val in l:
            digit = val // (10**i) % 10
            buckets[digit].append(val)
        l.clear()
        for bucket in buckets:
            for val in bucket:
                l.append(val)
        i += 1
    return l
print(radix_sort([234,345,333,456,674,4567,23,345,56,67,78,6]))

#写l.reverse()函数   前后交换
#[1,2,3,4,5]  0,1
#[1,2,3,4,5,6] 0,1,2
#[1,2,3,4,5,6,7] 0,1,2
#  n // 2 - 1

def reverse_list(l):
    n = len(l)
    for i in range(n // 2):
        l[i], l[n-i-1] = l[n-i-1], l[i]
    return l

#反转数字

def reverse_int(num):
    res = 0
    while num > 0:
        res = res * 10
        res += num % 10
        num = num // 10
    return res
#数字为负数
def reverse_int1(num):
    is_neg = False
    if num < 0:
        is_neg = True
        num = num * -1
    res = 0
    while num > 0:
        res = res * 10
        res += num % 10
        num = num // 10
    if is_neg:
        res = res * -1
    return res

print(reverse_int1(-67801))