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\backslash
exerc1[00]
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Considering COBOL data configurations as tree structures,
are the data items listed by a COBOL programmer in preorder,
postorder,
or neither of these orders?
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answer
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They are in preorder.
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exerc2[10]
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Comment about the running time of Algorithm A.
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answer
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It takes a constant amount of time for each data item read (assuming that accessing the symbol table takes constant time).
There is also a loop to get out of a nested record,
but each iteration of the loop takes out an item from the stack so we may consider that as part of processing such item.
Therefore the running time is proportional to the number of data items in the input.
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exerc8[10]
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Under what circumstances is
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according to the definition in the text?
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answer
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When
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is an elementary item.
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rexerc11[23]
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What additional links or changes in the strategy of the algorithms of the text could make Algorithm B or Algorithm C faster?
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(I had to look up the solution.)
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One could make Algorithm C faster by storing sibling nodes in the table in lexicographical order,
so step C3 would have a linear rather than quadratic complexity.
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rexerc13[24]
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Give an algorithm to substitute for Algorithm A when the Data Table is to have the format shown in exercise 12.
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answer
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We remove the instructions that set
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PARENT
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CHILD
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SIB
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and
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NAME
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as those fields do not exist now (in particular,
A6 disappears),
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We set the
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so we could just do those instructions unconditionally,
then after removing the current stack item and before loading the next one we check if
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and if so we go to A7,
then if
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we repeat,
otherwise we report the error.)
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For this to work,
we have to get the stack empty by the time the algorithm finishes,
which we can do by setting
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when the input is exhausted in step A2 and then terminate in step A7 when
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.
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|
