Compress repeated sequences by writing each run as a count followed by the symbol. Pick a format, encode or decode live, and see how much space you saved vs. the raw input.
count+symbol for every run — always works but adds a digit even for singletons.
Omit 1 skips the 1 prefix for single-character runs to save space when input has few repeats.
Brace wraps the count in {n} so digit symbols are unambiguous.