Is Substring Solution

is_substring_solution.py

# Solution for Is A Substring Problem

def is_substring(short:str, long:str) -> bool:
   for i, c in enumerate(long):
       if c == short[0]:
           if long[i:i+len(short)] == short:
               return True
   else:
       return False

assert is_substring(short="lo", long="Hello, world!")      # Short in long
assert not is_substring(short= "🦄", long="Hello, world!") # Not (short in long)      
      
"""
Notes to interviewer
-------

Common Questions
-----

- Q: Can I use built-in string methods?
   - A: No
- Q: Can I use `in`?
   - A: No
- Q: Should I care about case?
   - A: Yes - It needs to be an exact character match
- Q: Can the strings be empty?
   - A: Assume both strings are not empty

Big 0
-----
Time: O(n) / linear - where n is the length of the longer string
Space: 0(1) / constant - takes no more space


"""