sublist_rank.py

def suffixes(string):
    return [ string[i:] for i in range(len(string)) ]

def common_prefix(string1, string2):
    for i, (c1, c2) in enumerate(zip(string1, string2)):
        if c1 != c2:
            return i
    return min(len(string1), len(string2))

def sublist_rank(target):
    running_total = 0
    for suffix in sorted(suffixes(target)):
        if suffix <= target:
            running_total += len(suffix)
        else:
          prefix_len = common_prefix(suffix, target)
          if prefix_len == 0:
              break
          running_total += prefix_len

    return running_total