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Kolakoski sequence: Difference between revisions
Add Rust implementation
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</pre>
=={{header|Rust}}==
<lang rust>
use itertools::Itertools;
fn get_kolakoski_sequence(iseq: &[usize], size: &usize) -> Vec<usize> {
assert!(*size > 0);
assert!(!iseq.is_empty());
let mut kseq: Vec<usize> = Vec::default();
// create an itertor which keeps repeating the initial sequence infinitely
let repeater = iseq.iter().cloned().cycle();
// push the very first element, repeated as many times as the number
kseq.extend_from_slice(&vec![*iseq.get(0).unwrap()].repeat(*iseq.get(0).unwrap()));
//start cycling throught the initial sequence, but skip the very first one
for (k_counter, elem) in repeater.enumerate().skip(1) {
// push the given element
kseq.push(elem);
// and repeat the current element as many times
// as it's needed based on the previous elements
kseq.extend_from_slice(&vec![elem].repeat(*kseq.get(k_counter).unwrap() - 1));
// finish generation when the Kolakoski sequence has reached the given length
if kseq.len() >= *size {
break;
}
}
// truncate it as it might have more elements than needed
kseq[0..*size].to_vec()
}
fn is_kolakoski(kseq: &[usize]) -> bool {
assert!(!kseq.is_empty());
// calculate the RLE
let rle: Vec<usize> = kseq
.iter()
.batching(|it| {
it.next()
.map(|v| it.take_while_ref(|&v2| v2 == v).count() + 1)
})
.collect();
rle.iter().zip(kseq).filter(|&(a, b)| a == b).count() == rle.len()
}
fn main() {
let lengths = vec![20, 20, 30, 30];
let seqs = vec![vec![1, 2], vec![2, 1], vec![1, 3, 1, 2], vec![1, 3, 2, 1]];
for (seq, length) in seqs.iter().zip(&lengths) {
let kseq = get_kolakoski_sequence(&seq, length);
println!("Starting sequence: {:?}", seq);
println!("Kolakoski sequence: {:?}", kseq);
println!("Possible Kolakoski sequence? {:?}", is_kolakoski(&kseq));
}
}
</lang>
{{out}}
<pre>
Starting sequence: [1, 2]
Kolakoski sequence: [1, 2, 2, 1, 1, 2, 1, 2, 2, 1, 2, 2, 1, 1, 2, 1, 1, 2, 2, 1]
Possible Kolakoski sequence? true
Starting sequence: [2, 1]
Kolakoski sequence: [2, 2, 1, 1, 2, 1, 2, 2, 1, 2, 2, 1, 1, 2, 1, 1, 2, 2, 1, 2]
Possible Kolakoski sequence? true
Starting sequence: [1, 3, 1, 2]
Kolakoski sequence: [1, 3, 3, 3, 1, 1, 1, 2, 2, 2, 1, 3, 1, 2, 2, 1, 1, 3, 3, 1, 2, 2, 2, 1, 3, 3, 1, 1, 2, 1]
Possible Kolakoski sequence? true
Starting sequence: [1, 3, 2, 1]
Kolakoski sequence: [1, 3, 3, 3, 2, 2, 2, 1, 1, 1, 1, 1, 3, 3, 2, 2, 1, 1, 3, 2, 1, 1, 1, 1, 3, 3, 3, 2, 2, 1]
Possible Kolakoski sequence? false
</pre>
=={{header|Sidef}}==
{{trans|Ruby}}
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