11.py

def HammingDistance(a, b):
    a = a.lower()
    b = b.lower()
    hd = 0
    for i in range(len(a)):
        if a[i] != b[i]:
            hd += 1
    return(hd)


def Suffix(Pattern): 
    return Pattern[1:]

def Neighbors(Pattern, d): 
    if d == 0: 
        return {Pattern}
    if len(Pattern) == 1: 
        return {'A', 'C', 'G', 'T'}
    Neighborhood = set()
    SuffixNeighbors = Neighbors(Suffix(Pattern), d)
    # for each string Text from SuffixNeighbors:
    for Text in SuffixNeighbors:
        if HammingDistance(Suffix(Pattern), Text) < d:
            # for each nucleotide x:
            for x in 'ATCG':
                # add x • Text to Neighborhood
                Neighborhood.add(x+Text)
        else:
            # add FirstSymbol(Pattern) • Text to Neighborhood
            Neighborhood.add(Pattern[0]+Text)

    return Neighborhood


samp = 'CATCACGTGC'
# x = Suffix(samp)
# print(x)

# z = Neighbors('ACG', 1)
z = Neighbors(samp, 2)
print(z)

for i in list(z): 
    print(i)

print(len(list(z)))