Python – N 大小的子字符串，具有 K 个不同的字符

给定一个字符串，任务是编写一个Python程序来提取大小为 N 且具有 K 个不同字符的字符串。

例子：

Input : test_str = ‘geeksforgeeksforgeeks’, N = 3, K = 2 
Output : [‘gee’, ‘eek’, ‘gee’, ‘eek’, ‘gee’, ‘eek’] 
Explanation : 3 lengths have 2 unique characters are extracted.

Input : test_str = ‘geeksforgeeksforgeeks’, N = 4, K = 2 
Output : [] 
Explanation : No strings with 4 length and just have 2 elements. 

方法 #1：使用切片+ set() + 循环

在此我们执行使用切片获取 N 个块的任务，set() 用于检查唯一元素。循环用于迭代所有可能的块。

Python3

# Python3 code to demonstrate working of
# N sized substrings with K distinct characters
# Using slicing + set() + loop
 
# initializing string
test_str = 'geeksforgeeksforgeeks'
 
# printing original string
print("The original string is : " + str(test_str))
 
# initializing N
N = 3
 
# initializing K
K = 2
 
res = []
for idx in range(0, len(test_str) - N + 1):
 
    # getting unique elements off sliced string
    if (len(set(test_str[idx: idx + N])) == K):
        res.append(test_str[idx: idx + N])
 
# printing result
print("Extracted Strings : " + str(res))

输出

The original string is : geeksforgeeksforgeeks
Extracted Strings : ['gee', 'eek', 'gee', 'eek', 'gee', 'eek']

方法 #2：使用列表推导+ len() + set() +切片

与上述方法类似，唯一的区别是使用列表理解而不是循环，只是为了提供解决此任务的速记。

蟒蛇3

# Python3 code to demonstrate working of
# N sized substrings with K distinct characters
# Using list comprehension + len() + set() + slicing
 
# initializing string
test_str = 'geeksforgeeksforgeeks'
 
# printing original string
print("The original string is : " + str(test_str))
 
# initializing N
N = 3
 
# initializing K
K = 2
 
# list comprehension used to slice
res = [test_str[idx: idx + N]
       for idx in range(0, len(test_str) - N + 1)
       if len(set(test_str[idx: idx + N])) == K]
 
# printing result
print("Extracted Strings : " + str(res))

输出

The original string is : geeksforgeeksforgeeks
Extracted Strings : ['gee', 'eek', 'gee', 'eek', 'gee', 'eek']