Python3练习:实现冒泡、选择、插入、快速排序

1. 冒泡排序

# 冒泡排序
# 需比较len(seq)-1轮。每轮在下标0到len(seq)-i-1的数中,每一个数与它后面一个数比较,大数后移(冒泡),每轮中最大的数冒泡排到本轮最后
def bubble_sort(seq):
    seq = copy.deepcopy(seq1
    for i in range(len(seq)-1):
        for j in range(len(seq)-i-1):
            if seq[j] > seq[j+1]:  # 相邻两数比较,大数后移
                seq[j], seq[j+1] = seq[j+1], seq[j]
    return seq

2. 选择排序

# 选择排序
# 需比较len(seq)-1轮。下标0到i的数已排好序,下标i的数与后面的数分别比较,选择出最小的数给seq[i]
def selection_sort(seq):for i in range(len(seq)-1):
        for j in range(i+1, len(seq)):
            if seq[i] > seq[j]:
                seq[i], seq[j] = seq[j], seq[i]
    return seq

3. 插入排序

# 插入排序
# 需比较len(seq)-1轮。下标0到i的数已排好序,下标i的数(val)与前面的每个数(从后往前)比较,并插入到比它大的数前面
def insert_sort(seq):for i in range(1, len(seq)):
        val = seq[i]
        idx = i
        while val < seq[idx-1] and idx > 0:
            seq[idx], seq[idx-1] = seq[idx-1], val
            idx -= 1
    return seq

4. 快速排序

# 快速排序1(用递归函数实现)
def quick_sort(seq):if len(seq) <= 1:
        return seq
    return quick_sort([s for s in seq[1:] if s < seq[0]]) + seq[0:1] + quick_sort([m for m in seq[1:] if m >= seq[0]])

# 快速排序2(用匿名函数实现)
qsort = lambda seq: \
        seq if len(seq) <= 1 else qsort(
                                      [item for item in seq[1:] if item <= seq[0]]) \
                                      + [seq[0]] \
                                      + qsort([item for item in seq[1:] if item > seq[0]]
                                  )

posted on 2019-01-22 15:18  iouwenbo  阅读(374)  评论(0编辑  收藏  举报

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