# Lab 08

# Q1: Insert

    if index == 0:
        link.rest = Link(link.first,link.rest)
        link.first = value
    elif link.rest is Link.empty:
        raise IndexError
    else:
        insert(link.rest, value, index - 1)
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# Q2: Determining Efficiency

答案:wwpd-efficiency.py

# Q3: Subsequences

def insert_into_all(item, nested_list):
    return [[item] + rest for rest in nested_list]

def subseqs(s):
    if not s:
        return [[]]
    else:
        with_in = insert_into_all(s[0],subseqs(s[1:]))
        with_out = subseqs(s[1:])
        return with_in + with_out
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