任意长度子串的运行长度编码

Question

What's efficient (in terms of both time complexity) run length encoding algorithm for an arbitrary but finite length of input stream. An algorithm for substrings of length 1 can be implemented in C as:

void encoding(char *bytes)
{
    int c = 0; 
    char *s = bytes, ch;

    while(*s) {
       c=1;
       ch=*s;

       while(*s && *s== *(s+1)) {
          c++;
          s++;
       }
       printf("%d%c", c, ch);
       s++;
    }
}

However, I am looking for a better algorithm that can encode substrings of any length. For example, for the input "abbabb" the above code will print: "1a2b1a2b" . But a better algorithm could encode it as "2abb" .

The implementation language (C/Python is my choice) is not an issue as an algorithm is all I am looking for.

Answer 1

Any algorithm that can find a certain length repeated substring can be used to implement Lempel-Ziv compression with a sliding window of that length.

So I would look into Lempel-Ziv encoders and use that. Or even better: drop the run length encoding and implement Lempel-Ziv - it can only provide better compression.