checkSubsequence.py

# check if s is a subsquence of S
def checkSubsequence(s, S):
    idx = 0
    for char in s:
        if idx >= len(S):
            return False
        while char != S[idx]:
            idx += 1
            if idx >= len(S):
                return False
        idx += 1
    return True

assert checkSubsequence("12345", "1234") is False
assert checkSubsequence("01234", "1234") is False
assert checkSubsequence("0123", "1234") is False
assert checkSubsequence("1723", "1234") is False
assert checkSubsequence("6", "1234") is False
assert checkSubsequence("0", "1234") is False

assert checkSubsequence("1234", "1234") is True
assert checkSubsequence("123", "1234") is True
assert checkSubsequence("23", "1234") is True
assert checkSubsequence("24", "1234") is True
assert checkSubsequence("134", "1234") is True
assert checkSubsequence("1", "1234") is True
assert checkSubsequence("2", "1234") is True
assert checkSubsequence("3", "1234") is True
assert checkSubsequence("4", "1234") is True