Compression
To reduce the size of messages transmitted over the internet, a compression algorithm encodes consecutive repeating characters in a string.
Your task is to compress the given string using this rule:
- Scan the string from left to right and group consecutive identical characters.
- If a character appears once, add just the character to the output.
- If a character appears more than once in a row, add the character followed by the number of consecutive occurrences.
Example
Suppose message = "aabbccca".
Output: a2b2c3a
Complete the compressedString function below.
The function is expected to return a STRING.
The function accepts STRING message as parameter.
Constraints
- All characters in
messageare in the rangeascii[a-z]. length of message <= 10^5
This problem asks you to run-length encode a lowercase string by compressing each maximal block of identical characters. A single character stays as-is, while repeated characters are written as the character plus its count. The key is a one-pass linear scan with a counter or two pointers, which produces an O(n) solution and works efficiently for strings up to 10^5 characters.
