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Non-continuous subsequences: Difference between revisions
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print len( ncsub(range(1, n)) )
</pre>
=={{header|R}}==
The idea behind this is to loop over the possible lengths of subsequence, finding all subsequences then discarding those which are continuous.
<lang r>
ncsub <- function(x)
{
n <- length(x)
a <- seq_len(n)
seqlist <- list()
for(i in 2:(n-1))
{
seqs <- combn(a, i) # Get all subseqs
ok <- apply(seqs, 2, function(x) any(diff(x)!=1)) # Find noncts ones
newseqs <- unlist(apply(seqs[,ok], 2, function(x) list(x)), recursive=FALSE) # Convert matrix to list of its columns
seqlist <- c(seqlist, newseqs) # Append to existing list
}
lapply(seqlist, function(index) x[index])
}
# Example usage
ncsub(1:4)
ncsub(letters[1:5])
</lang>
=={{header|Ruby}}==
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