3.16. Substring Count

Write a function called substring_count that takes two strings and returns how many times the second string occurs in the first one as an integer. Note that the overlapping occurrences should be counted as well (see 3rd example in Sample I/O).

Sample I/O:

Input:
>>> substring_count("stanrandystancartmanstankenny","stan")
3

>>> substring_count("taktakatutakatakataktuk","ta")
5

>>> substring_count("ababa","aba")
2

Show the Answer

def substring_count(first, second):
    count = 0
    length_of_first = len(first)
    length_of_second = len(second)
    for i in range(0, length_of_first-length_of_second+1):    # Notice the narrowing of the indices to possible occurrence range.
        if s[i:i+length_of_second] == k:
            count+=1
    return count