Implement run-length encoding and decoding

You are given a string consisting of lowercase English letters. You need to implement run-length encoding (RLE) and its corresponding decoding.

1. Encoding
   • Input: a string s , e.g., "aaabccccd" .
   • Output: an encoded string where each maximal group of consecutive identical characters is replaced by the character followed by the count of repetitions, e.g., "a3b1c4d1" .
2. Decoding
   • Input: an RLE-encoded string as described above, which is always valid (i.e., alternates between characters and positive integer counts), e.g., "a3b1c4d1" .
   • Output: the original string, e.g., "aaabccccd" .

Constraints:

• 0 <= len(s) <= 10^5 for both encoding and decoding inputs.
• Counts in the encoded string fit in a 32-bit signed integer.

Tasks:

• Describe how to implement encode(String s) and decode(String encoded) .
• Explain the time and space complexity of each function.
• Consider edge cases such as empty strings and runs of length 1.