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21 lines
722 B
21 lines
722 B
2 years ago
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Exercise 2.68: The encode procedure takes
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as arguments a message and a tree and produces the list of bits that gives the
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encoded message.
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(define (encode message tree)
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(if (null? message)
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'()
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(append
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(encode-symbol (car message)
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tree)
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(encode (cdr message) tree))))
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Encode-symbol is a procedure, which you must write, that returns the
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list of bits that encodes a given symbol according to a given tree. You should
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design encode-symbol so that it signals an error if the symbol is not in
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the tree at all. Test your procedure by encoding the result you obtained in
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Exercise 2.67 with the sample tree and seeing whether it is the same as
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the original sample message.
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