# Kolakoski sequence

```ruby
func create_generator(arr) {
    Enumerator({|f|
        var s = []
        var i = 0
        loop {
            var t = arr[i++ % arr.len]
            s << t
            f(var v = s.shift)
            s << (v-1).of(t)...
        }
    })
}

var tests = [
    [20, [1,2]],
    [20, [2,1]],
    [30, [1,3,1,2]],
    [30, [1,3,2,1]]
]

for num,arr in (tests) {
    say "\nFirst #{num} of the sequence generated by #{arr}:"
    var res = create_generator(arr).first(num)
    var rle = res.run_length.map{.tail}
    say "#{res}\nPossible Kolakoski sequence? #{res.first(rle.len) == rle}"
}
```

## Output:

```
First 20 of the sequence generated by [1, 2]:
[1, 2, 2, 1, 1, 2, 1, 2, 2, 1, 2, 2, 1, 1, 2, 1, 1, 2, 2, 1]
Possible Kolakoski sequence? true

First 20 of the sequence generated by [2, 1]:
[2, 2, 1, 1, 2, 1, 2, 2, 1, 2, 2, 1, 1, 2, 1, 1, 2, 2, 1, 2]
Possible Kolakoski sequence? true

First 30 of the sequence generated by [1, 3, 1, 2]:
[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

First 30 of the sequence generated by [1, 3, 2, 1]:
[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
```


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://trizen.gitbook.io/sidef-lang/programming_tasks/k/kolakoski_sequence.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.