20 lines
989 B
Plaintext
20 lines
989 B
Plaintext
Consider some sequence of elements. (It differs from a mere set of elements by having an ordering among members.)
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A ''subsequence'' contains some subset of the elements of this sequence, in the same order.
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A ''continuous'' subsequence is one in which no elements are missing between the first and last elements of the subsequence.
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Note: Subsequences are defined ''structurally'', not by their contents.
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So a sequence ''a,b,c,d'' will always have the same subsequences and continuous subsequences, no matter which values are substituted; it may even be the same value.
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'''Task''': Find all non-continuous subsequences for a given sequence.
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Example: For the sequence ''1,2,3,4'', there are five non-continuous subsequences, namely:
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::::* ''1,3''
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::::* ''1,4''
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::::* ''2,4''
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::::* ''1,3,4''
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::::* ''1,2,4''
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'''Goal''': There are different ways to calculate those subsequences. Demonstrate algorithm(s) that are natural for the language.
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