word_abbr_v2.py

# Educative's official solution (23 vs. 29 lines of code):
def valid_word_abbreviation(word, abbr):
    word_index, abbr_index = 0, 0

    while abbr_index < len(abbr):
        # Check if the current character is a digit.
        if abbr[abbr_index].isdigit():
            # Check if there's a leading zero. If there is, return False.
            if abbr[abbr_index] == '0':
                return False
            num = 0

            while abbr_index < len(abbr) and abbr[abbr_index].isdigit():
                num = num * 10 + int(abbr[abbr_index])
                abbr_index += 1
            # Skip the number of characters in word as found in abbreviation.
            word_index += num
        else:
            # Check if characters the match, then increment the pointers. Otherwise return False.
            if word_index >= len(word) or word[word_index] != abbr[abbr_index]:
                return False
            word_index += 1
            abbr_index += 1

    # Check if both indices have reached the end of their respective strings.
    return word_index == len(word) and abbr_index == len(abbr)


def main():
    words = ["a", "a", "abcdefghijklmnopqrst", "abcdefghijklmnopqrst", "word", "internationalization", "localization"]
    abbreviations = ["a", "b", "a18t", "a19t", "w0rd", "i18n", "l12n"]

    for i in range(len(words)):
        print(i + 1, ".\t word: '", words[i], "'", sep="")
        print("\t abbr: ", abbreviations[i], "'", sep="")
        print(f"\n\t Is '{abbreviations[i]}' a valid abbreviation for the word '{words[i]}'? ", valid_word_abbreviation(words[i], abbreviations[i]), sep="")
        print("-" * 100)

if __name__ == '__main__':
    main()