Write count_overlapping(s, sub) that counts how many times sub occurs in s, including overlapping occurrences. Matching is case-sensitive.
Examples
Input: s = "aaaa", sub = "aa"
Output: 3
Explanation: positions 0, 1 and 2.
Input: s = "abababa", sub = "aba"
Output: 3
Input: s = "hello", sub = "z"
Output: 0
Constraints
0 <= len(s) <= 10**5,1 <= len(sub) <= 100, printable ASCII- Note that
s.count(sub)does not count overlaps
Goals
- Search for a substring starting from a given index
- Advance by one to allow overlaps
- Handle patterns longer than the text