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：窗口大小为20，前向缓冲区大小为10，搜索窗口大小10。
C(a) = 1, C( ) = 2, C(r) = 3, C(t) = 4
解码过程：
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 rat at
<9, 5, 4> ratatatatat a rat at a rat
编码过程：输入序列：ratatatatat a rat at a rat
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 a r|at at a rat <6, 4, 4>
ratatatata|t a rat at|a rat <9, 5, 4>
编码输出的三元组与解码输入的三元组完全一样。
8、给定以下初始词典和接收序列，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：
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索引 |
项 |
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1 |
S |
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2 |
P |
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3 |
I |
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4 |
T |
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5 |
H |
接收到的序列：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
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1 |
S |
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2 |
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I |
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4 |
T |
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5 |
H |
输入：4, 5, 3, 1, 2, 8, 2, 7, 9, 7, 4
字典： 解码出的序列：TH
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1 |
S |
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2 |
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4 |
T |
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H |
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6 |
TH |
输入：4, 5, 3, 1, 2, 8, 2, 7, 9, 7, 4
字典： 解码出的序列：THI
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1 |
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2 |
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5 |
H |
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6 |
TH |
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7 |
HI |
输入：4, 5, 3, 1, 2, 8, 2, 7, 9, 7, 4
字典： 解码出的序列：THIS
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1 |
S |
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2 |
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3 |
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4 |
T |
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5 |
H |
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6 |
TH |
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7 |
HI |
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8 |
IS |
输入：4, 5, 3, 1, 2, 8, 2, 7, 9, 7, 4
字典： 解码出的序列：THIS
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1 |
S |
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2 |
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3 |
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4 |
T |
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5 |
H |
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6 |
TH |
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7 |
HI |
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8 |
IS |
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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
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1 |
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2 |
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T |
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H |
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TH |
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HI |
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8 |
IS |
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9 |
S |
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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
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1 |
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2 |
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4 |
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5 |
H |
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6 |
TH |
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7 |
HI |
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8 |
IS |
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9 |
S |
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10 |
I |
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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
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1 |
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2 |
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3 |
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4 |
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5 |
H |
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6 |
TH |
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7 |
HI |
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8 |
IS |
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9 |
S |
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10 |
I |
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11 |
IS |
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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
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1 |
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2 |
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3 |
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4 |
T |
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5 |
H |
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TH |
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HI |
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8 |
IS |
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9 |
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10 |
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11 |
IS |
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12 |
H |
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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
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1 |
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2 |
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4 |
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TH |
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8 |
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9 |
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10 |
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11 |
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12 |
H |
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13 |
HIS |
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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
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1 |
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2 |
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3 |
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4 |
T |
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5 |
H |
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6 |
TH |
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7 |
HI |
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8 |
IS |
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9 |
S |
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10 |
I |
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11 |
IS |
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12 |
H |
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13 |
HIS |
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14 |
S H |
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15 |
HIT |