Python: Count number of substrings from a given string of lowercase alphabets with exactly k distinct characters
Substrings with k distinct characters.
Write a Python program to count the number of substrings from a given string of lowercase alphabets with exactly k distinct (given) characters.
Sample Solution:
Python Code:
# Function to count substrings with k distinct chars
def count_k_dist(str1, k):
# Get string length
str_len = len(str1)
result = 0
# Character counter array
ctr = [0] * 27
for i in range(0, str_len):
dist_ctr = 0
ctr = [0] * 27
for j in range(i, str_len):
# Increment distinct char count
if(ctr[ord(str1[j]) - 97] == 0):
dist_ctr += 1
# Increment char counter
ctr[ord(str1[j]) - 97] += 1
# Increment result if exactly k distinct
if(dist_ctr == k):
result += 1
# Break loop if > k distinct
if(dist_ctr > k):
break
return result
# Get input
str1 = input("Input a string (lowercase alphabets):")
k = int(input("Input k: "))
# Print result
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:
Python Code Editor:
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