1、 参考书《数据压缩导论（第4版）》 Page 121 7，8
7.使用LZ77算法对一个序列进行编码。给定C(a)=1,C(b)=2,C(r)=3,C(t)=4.对以下三元组序列进行解码：
<0,0,3> <0,0,1> <0,0,4> <2,8,2> <3,1,2> <0,0,3> <6,4,4> <9,5,4>
给定窗口的大小为20，先行缓冲区的大小为10。对解码所得到的序列进行编码，确保得到相同的三元组序列。
解：窗口大小20，前向冲区大小10，搜素窗口大小10，C(a)=1, C(b)=2, C(r)=3, C(t)=4,
解码过程如下：
| 输入 | 输出 |
| <0,0,3> | r |
| <0,0,1> | ra |
| <0,0,4> | rat |
| <2,8,2> | ratatatatat |
| <3,1,2> | ratatatatat a |
| <0,0,3> | ratatatatat a r |
| <6,4,4> | ratatatatat a r a t a t |
| <9,5,4> | ratatatatat a rat at a rat |
入序列：ratatatatat a rat at a rat
编码：
| 输入 | 输出 |
| ||ratatatatat a rat at a rat | <0,0,3> |
| |r|atatatatat a rat at a rat | <0,0,1> |
| |ra|tatatatat a rat at a rat | <0,0,4> |
| |rat|atatatat a rat at a rat | <2,8,2> |
| ra|tatatatat |a rat at a rat | <3,1,2> |
| rata|tatatat a| rat at a rat | <0,0,3> |
| ratat|atatat ar|at at a rat | <6,4,4> |
| ratatatata|t arat at| a rat | <9,5,4> |
8.给定一下初始词典和接受序列，构建一个LZW词典，并对所发送的序列进行解码。
接收序列：4,5,3,1,2,8,2,7,9,7,4
初始词典：
| 索引 | 项目 |
| 1 | S |
| 2 | B |
| 3 | I |
| 4 | T |
| 5 | H |
解：由题意可知，因为接收序列为：4,5,3,1,2,8,2,7,9,7,4，
所以输入序列为：4,5,3,1,2,8,2,7,9,7,4
（1）输入4,5,3,1,2,8,2,7,9,7,4
|
索引 |
条目 |
|
1 |
S |
|
2 |
_(空格) |
|
3 |
I |
|
4 |
T |
|
5 |
H |
解码的序列为：T
（2）输入4,5,3,1,2,8,2,7,9,7,4
|
索引 |
条目 |
|
1 |
S |
|
2 |
_ (空格) |
|
3 |
I |
|
4 |
T |
|
5 |
H |
解码的序列为：TH
（3）输入4,5,3,1,2,8,2,7,9,7,4
|
索引 |
条目 |
|
1 |
S |
|
2 |
_(空格) |
|
3 |
I |
|
4 |
T |
|
5 |
H |
|
6 |
TH |
解码的序列为：THI
（4）输入4,5,3,1,2,8,2,7,9,7,4
|
索引 |
条目 |
|
1 |
S |
|
2 |
_ (空格) |
|
3 |
I |
|
4 |
T |
|
5 |
H |
|
6 |
TH |
|
7 |
HI |
解码的序列为：THIS
（5）输入4,5,3,1,2,8,2,7,9,7,4
|
索引 |
条目 |
|
1 |
S |
|
2 |
_(空格) |
|
3 |
I |
|
4 |
T |
|
5 |
H |
|
6 |
TH |
|
7 |
HI |
|
8 |
IS |
解码的序列为：THIS_
（6）输入4,5,3,1,2,8,2,7,9,7,4
|
索引 |
条目 |
|
1 |
S |
|
2 |
_(空格) |
|
3 |
I |
|
4 |
T |
|
5 |
H |
|
6 |
TH |
|
7 |
HI |
|
8 |
IS |
|
9 |
S_ |
解码的序列为：THIS IS
（7）输入4,5,3,1,2,8,2,7,9,7,4
|
索引 |
条目 |
|
1 |
S |
|
2 |
_ (空格) |
|
3 |
I |
|
4 |
T |
|
5 |
H |
|
6 |
TH |
|
7 |
HI |
|
8 |
IS |
|
9 |
S_ |
|
10 |
_I |
解码的序列为：THIS IS_
（8）输入4,5,3,1,2,8,2,7,9,7,4
|
索引 |
条目 |
|
1 |
S |
|
2 |
_ (空格) |
|
3 |
I |
|
4 |
T |
|
5 |
H |
|
6 |
TH |
|
7 |
HI |
|
8 |
IS |
|
9 |
S_ |
|
10 |
_I |
|
11 |
IS_ |
解码的序列为：THIS IS HI
（9）输入4,5,3,1,2,8,2,7,9,7,4
|
索引 |
条目 |
|
1 |
S |
|
2 |
_ (空格) |
|
3 |
I |
|
4 |
T |
|
5 |
H |
|
6 |
TH |
|
7 |
HI |
|
8 |
IS |
|
9 |
S_ |
|
10 |
_I |
|
11 |
IS_ |
|
12 |
_H |
解码的序列为：THIS IS HIS_
（10）输入4,5,3,1,2,8,2,7,9,7,4
|
索引 |
条目 |
|
1 |
S |
|
2 |
_ (空格) |
|
3 |
I |
|
4 |
T |
|
5 |
H |
|
6 |
TH |
|
7 |
HI |
|
8 |
IS |
|
9 |
S_ |
|
10 |
_I |
|
11 |
IS_ |
|
12 |
_H |
|
13 |
HIS |
解码的序列为：THIS IS HIS HI
（11）输入4,5,3,1,2,8,2,7,9,7,4
|
索引 |
条目 |
|
1 |
S |
|
2 |
_ (空格) |
|
3 |
I |
|
4 |
T |
|
5 |
H |
|
6 |
TH |
|
7 |
HI |
|
8 |
IS |
|
9 |
S_ |
|
10 |
_I |
|
11 |
IS_ |
|
12 |
_H |
|
13 |
HIS |
|
14 |
S_H |
解码的序列为：THIS IS HIS HIT
综上所述该解码的序列为THIS IS HIS HIT