Move-to-front algorithm: Difference between revisions

Given a symbol table of a ''zero-indexed'' array of all possible input symbols

[[wp:Move-to-front transform|this algorithm]] reversibly transforms a sequence

The transform in many cases acts to give frequently repeated input symbols

lower indices which is [[wp:Move-to-front_transform#Use_in_practical_data_compression_algorithms| useful in some compression algorithms]].

 

;Encoding algorithm:

move that symbol to the front of the symbol table

</pre>

 

;Decoding algorithm:

move that symbol to the front of the symbol table

</pre>

 

;Example:

the characters 'a'-to-'z'

 

|-

! Input

| 'orbacdefghijklmnpqstuvwxyz'

|}

 

Decoding the indices back to the original symbol order:

|-

! Input

| 'orbacdefghijklmnpqstuvwxyz'

|}

 

;Task: