1. Run Length Encoding for
AAAABBBBBBBBBCADDDDEEFFFFFFFF
Format = Character then Count (A4)

Solution:
Run Length Encoding for AAAABBBBBBBBBCADDDDEEFFFFFFFF

Find consecutive letters

AAAA : A is repeated 4 times : A4

BBBBBBBBB : B is repeated 9 times : B9

C : C is repeated 1 times : C1

A : A is repeated 1 times : A1

DDDD : D is repeated 4 times : D4

EE : E is repeated 2 times : E2

FFFFFFFF : F is repeated 8 times : F8

So, AAAABBBBBBBBBCADDDDEEFFFFFFFF = A4B9C1A1D4E2F8