Feng Juan's fourth time assignment

Reference exercises:

7. Encode a sequence using the LZ77 algorithm. Given C (a) =1,c (b) =2,c (R) =3,c (t) = 5, the ternary sequence is decoded:

<0,0,3><0,0,1><0,0,4><2,8,2><3,1,2><0,0,3><6,4,4><9,5,4>

Assume that the size of the window is 20, the size of the antecedent buffer is 10. Encode the sequence obtained by decoding to ensure that the same ternary sequence is obtained.

Solution:

Sequence	Output
<0,0,3>	R
<0,0,1>	Ra
<0,0,4>	Rat
<2,8,2>	Ratatatatatb
<3,1,2>	Ratatatatatbab
<0,0,3>	Ratatatatatbabr
<6,4,4,>	Ratatatatatbabratbat
<9,5,4>	Ratatatatatbabratbatbabrat

Encoding process:

Input sequence: Rat Atatatatbabratbatbabrat

Input	Output
R _atatatatatbabratbatbabrat	<0,0,3>
Ra_ Tatatatatbabratbatbabrat	<0,0,1>
Rat _ Atatatatbabratbatbabrat	<0,0,4>
R _atatatatatb_ Abratbatbabrat	<2,8,2>
Rat_ Atatatatba _ Bratbatbabrat	<3,1,2>
Rata _ tatatatbab _ Ratbatbabrat	<0,0,3>
Ratatatatatbabratbatbabrat	<6,4,4,>
Ratatatatatbabratbatbabrat	<9,5,4>

8. Given the following initial dictionaries and acceptance sequences, construct an LZW dictionary and decode the multiple sent sequences. Acceptance sequence: 4,5,3,1,2,8,2,7,9,7,4

Initial dictionary:

Index	Item
1	S
2	P
3	I
4	T
5	H

Solution:

1) Input 4,5,3,1,2,8,2,7,9,7,4

Index	Entry
1	S
2	_
3	I
4	T
5	H

The decoded sequence is: T

2) Input 4,5,3,1,2,8,2,7,9,7,4

Index	Entry
1	S
2	-
3	I
4	T
5	H

The decoded sequence is: TH

3) Input 4,5,3,1,2,8,2,7,9,7,4

Index	Entry
1	S
2	_
3	I
4	T
5	H
6	TH

The decoded sequence is: THI

10) Input 4,5,3,1,2,8,2,7,9,7,4

Index	Entry
1	S
2	_
3	I
4	T
5	H
6	TH
7	Hi
8	Is
9	S_
10	_i
11	Is_
12	_h
13	His

The decoded sequence is: The is the his HI

11) Input 4,5,3,1,2,8,2,7,9,7,4

Index	Entry
1	S
2	_
3	I
4	T
5	H
6	TH
7	Hi
8	Is
9	S_
10	_i
11	Is_
12	_h
13	His
14	R_i

The decoded sequence is:

The last decoding sequence is:

Feng Juan's fourth time assignment