count the substring of 1's

The given binary string S and integer K, to find count the number of substrings that contain exactly K ones.

Example-1:

Input    : s = "10010" k = 1
Output   : 9 
Explain  : The 9 substrings containing k 1's are, “1”, “1”, “10”, “01”, “10”,
          “100”, “001”, “010” and “0010”.

Example-2:

Input    : s = "1011" k = 2
Output   : 3
Explain  : The 3 substrings containing k 1's are, “11”, “101”, “011”.

Solution

s = "10010"

k = 1

l = []

for i in range(k,len(s)):

    for j in range(0,len(s)):

        a = s[j:j+i]

        if(len(a)==i and a.count("1")==k):

            l.append(a)

print(len(l))

Output