String Compression Python Solution with Tests

lcpy gen -n 443   # by problem number
lcpy gen -s string_compression   # by problem name

Input: chars = ["a","a","b","b","c","c","c"]
Output: 6
Explanation: The groups are "aa", "bb", and "ccc". This compresses to "a2b2c3".
After modifying the input array in-place, the first 6 characters of chars should be ["a","2","b","2","c","3"].

Input: chars = ["a"]
Output: 1
Explanation: The only group is "a", which remains uncompressed since it is a single character.
After modifying the input array in-place, the first character of chars should be ["a"].

Input: chars = ["a","b","b","b","b","b","b","b","b","b","b","b","b"]
Output: 4
Explanation: The groups are "a" and "bbbbbbbbbbbb". This compresses to "ab12".
After modifying the input array in-place, the first 4 characters of chars should be ["a","b","1","2"].

class Solution:
    # Time: O(n)
    # Space: O(1)
    def compress(self, chars: list[str]) -> int:
        write = 0
        read = 0
        n = len(chars)
        while read < n:
            ch = chars[read]
            run_start = read
            while read < n and chars[read] == ch:
                read += 1
            run_length = read - run_start
            chars[write] = ch
            write += 1
            if run_length > 1:
                for digit in str(run_length):
                    chars[write] = digit
                    write += 1
        return write