my_list = ['peek', "leak", 'creek', "weak", "good", 'week', "wood", "sneek"]

print("列表是：")
print(my_list)

K = 3

print("K的值是 ")
print(K)

my_result = {}

for element in my_list:
    suff = element[-K:]
    try:
        my_result[suff].append(element)
    except:
        my_result[suff] = [element]

print("结果列表是：")
print(my_result)

列表是:
['peek', 'leak', 'creek', 'weak', 'good', 'week', 'wood', 'sneek']
K的值是
3
结果列表是:
{'ood': ['good', 'wood'], 'eak': ['leak', 'weak'], 'eek': ['peek', 'creek', 'week', 'sneek']}