7、使用LZ77算法对一个序列进行编码。给定C(a)=1，C(p)=2，C(r)=3，C(t)=4。对已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>
假定窗口的大小为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：(1)由于C(a)=1,C(b)=2,C(r)=3,C(t)=4,所以解码的结果如下：
|
序列 |
输出 |
|
<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 |
（2）编码：由于窗口的大小为20，先进性缓冲区的大小为10，则编码缓冲区的大小为10
开始解码序列为：ratatatatatbabratbatbabrat
输入序列为： l ratatatatatbabratbatbabrat 没有与r匹配的项 则输出三元组为：<0,0,3>
输入序列为：r l atatatatatbabratbatbabrat 没有与a匹配的项 则输出三元组为：<0,0,1>
输入序列为：ra l tatatatatbabratbatbabrat 没有与t匹配的项 则输出三元组为：<0,0,4>
解：
由于接收序列为：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
输入：4, 5, 3, 1, 2, 8, 2, 7, 9, 7, 4
字典： 解码出的序列：T
|
1 |
S |
|
2 |
|
|
3 |
I |
|
4 |
T |
|
5 |
H |
输入：4, 5, 3, 1, 2, 8, 2, 7, 9, 7, 4
字典： 解码出的序列：TH
|
1 |
S |
|
2 |
|
|
3 |
I |
|
4 |
T |
|
5 |
H |
|
6 |
TH |
输入：4, 5, 3, 1, 2, 8, 2, 7, 9, 7, 4
字典： 解码出的序列：THI
|
1 |
S |
|
2 |
|
|
3 |
I |
|
4 |
T |
|
5 |
H |
|
6 |
TH |
|
7 |
HI |
输入：4, 5, 3, 1, 2, 8, 2, 7, 9, 7, 4
字典： 解码出的序列：THIS
|
1 |
S |
|
2 |
|
|
3 |
I |
|
4 |
T |
|
5 |
H |
|
6 |
TH |
|
7 |
HI |
|
8 |
IS |
输入：4, 5, 3, 1, 2, 8, 2, 7, 9, 7, 4
字典： 解码出的序列：THIS
|
1 |
S |
|
2 |
|
|
3 |
I |
|
4 |
T |
|
5 |
H |
|
6 |
TH |
|
7 |
HI |
|
8 |
IS |
|
9 |
S |
输入：4, 5, 3, 1, 2, 8, 2, 7, 9, 7, 4
字典： 解码出的序列：THIS IS
|
1 |
S |
|
2 |
|
|
3 |
I |
|
4 |
T |
|
5 |
H |
|
6 |
TH |
|
7 |
HI |
|
8 |
IS |
|
9 |
S |
|
10 |
I |
输入：4, 5, 3, 1, 2, 8, 2, 7, 9, 7, 4
字典： 解码出的序列：THIS IS
|
1 |
S |
|
2 |
|
|
3 |
I |
|
4 |
T |
|
5 |
H |
|
6 |
TH |
|
7 |
HI |
|
8 |
IS |
|
9 |
S |
|
10 |
I |
|
11 |
IS |
输入：4, 5, 3, 1, 2, 8, 2, 7, 9, 7, 4
字典： 解码出的序列：THIS IS HI
|
1 |
S |
|
2 |
|
|
3 |
I |
|
4 |
T |
|
5 |
H |
|
6 |
TH |
|
7 |
HI |
|
8 |
IS |
|
9 |
S |
|
10 |
I |
|
11 |
IS |
|
12 |
H |
输入：4, 5, 3, 1, 2, 8, 2, 7, 9, 7, 4
字典： 解码出的序列：THIS IS HIS
|
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 |
输入：4, 5, 3, 1, 2, 8, 2, 7, 9, 7, 4
字典： 解码出的序列：THIS IS HIS HI
|
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 |
S H |
输入：4, 5, 3, 1, 2, 8, 2, 7, 9, 7, 4
字典： 解码出的序列：THIS IS HIS HIT
|
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 |
S H |
|
15 |
HIT |