Python: Count number of substrings from a given string of lowercase alphabets with exactly k distinct characters
Python String: Exercise-76 with Solution
Write a Python program to count number of substrings from a given string of lowercase alphabets with exactly k distinct (given) characters.
Sample Solution:-
Python Code:
def count_k_dist(str1, k):
str_len = len(str1)
result = 0
ctr = [0] * 27
for i in range(0, str_len):
dist_ctr = 0
ctr = [0] * 27
for j in range(i, str_len):
if(ctr[ord(str1[j]) - 97] == 0):
dist_ctr += 1
ctr[ord(str1[j]) - 97] += 1
if(dist_ctr == k):
result += 1
if(dist_ctr > k):
break
return result
str1 = input("Input a string (lowercase alphabets):")
k = int(input("Input k: "))
print("Number of substrings with exactly", k, "distinct characters : ", end = "")
print(count_k_dist(str1, k))
Sample Output:
Input a string (lowercase alphabets): wolf Input k: 4 Number of substrings with exactly 4 distinct characters : 1
Flowchart:
Visualize Python code execution:
The following tool visualize what the computer is doing step-by-step as it executes the said program:
Python Code Editor:
Have another way to solve this solution? Contribute your code (and comments) through Disqus.
Previous: Write a Python program to find smallest window that contains all characters of a given string.
Next: Write a Python program to count number of non-empty substrings of a given string.
What is the difficulty level of this exercise?
Test your Programming skills with w3resource's quiz.
Python: Tips of the Day
Find current directory and file's directory:
To get the full path to the directory a Python file is contained in, write this in that file:
import os dir_path = os.path.dirname(os.path.realpath(__file__))
(Note that the incantation above won't work if you've already used os.chdir() to change your current working directory, since the value of the __file__ constant is relative to the current working directory and is not changed by an os.chdir() call.)
To get the current working directory use
import os cwd = os.getcwd()
Documentation references for the modules, constants and functions used above:
- The os and os.path modules.
- The __file__ constant
- os.path.realpath(path) (returns "the canonical path of the specified filename, eliminating any symbolic links encountered in the path")
- os.path.dirname(path) (returns "the directory name of pathname path")
- os.getcwd() (returns "a string representing the current working directory")
- os.chdir(path) ("change the current working directory to path")
Ref: https://bit.ly/3fy0R6m
- New Content published on w3resource:
- HTML-CSS Practical: Exercises, Practice, Solution
- Java Regular Expression: Exercises, Practice, Solution
- Scala Programming Exercises, Practice, Solution
- Python Itertools exercises
- Python Numpy exercises
- Python GeoPy Package exercises
- Python Pandas exercises
- Python nltk exercises
- Python BeautifulSoup exercises
- Form Template
- Composer - PHP Package Manager
- PHPUnit - PHP Testing
- Laravel - PHP Framework
- Angular - JavaScript Framework
- Vue - JavaScript Framework
- Jest - JavaScript Testing Framework