4.8 KiB
4.8 KiB
id | title | challengeType | forumTopicId |
---|---|---|---|
5ea281203167d2b0bdefca00 | Ludic numbers | 5 | 385282 |
Description
2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 ...
(Loop)
- Take the first member of the resultant array as the next ludic number 2.
- Remove every 2nd indexed item from the array (including the first).
2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 ...
- (Unrolling a few loops...)
- Take the first member of the resultant array as the next ludic number 3.
- Remove every 3rd indexed item from the array (including the first).
3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 ...
- Take the first member of the resultant array as the next ludic number 5.
- Remove every 5th indexed item from the array (including the first).
5 7 11 13 17 19 23 25 29 31 35 37 41 43 47 49 53 55 59 61 65 67 71 73 77 ...
- Take the first member of the resultant array as the next ludic number 7.
- Remove every 7th indexed item from the array (including the first).
7 11 13 17 23 25 29 31 37 41 43 47 53 55 59 61 67 71 73 77 83 85 89 91 97 ...
- ...
- Take the first member of the current array as the next ludic number L.
- Remove every Lth indexed item from the array (including the first).
- ...
Instructions
Tests
tests:
- text: <code>ludic</code> should be a function.
testString: assert(typeof ludic === 'function', '<code>ludic</code> should be a function.');
- text: <code>ludic(2)</code> should return a array.
testString: assert(Array.isArray(ludic(2)));
- text: <code>ludic(2)</code> should return <code>[1, 2]</code>.
testString: assert.deepEqual(ludic(2), [1, 2]);
- text: <code>ludic(3)</code> should return <code>[1, 2, 3]</code>.
testString: assert.deepEqual(ludic(3), [1, 2, 3]);
- text: <code>ludic(5)</code> should return <code>[1, 2, 3, 5]</code>.
testString: assert.deepEqual(ludic(5), [1, 2, 3, 5]);
- text: <code>ludic(20)</code> should return <code>[1, 2, 3, 5, 7, 11, 13, 17]</code>.
testString: assert.deepEqual(ludic(20), [1, 2, 3, 5, 7, 11, 13, 17]);
- text: <code>ludic(26)</code> should return <code>[1, 2, 3, 5, 7, 11, 13, 17, 23, 25]</code>.
testString: assert.deepEqual(ludic(26), [1, 2, 3, 5, 7, 11, 13, 17, 23, 25]);
Challenge Seed
function ludic(n) {
}
Solution
function ludic(n) {
const makeArr = (s, e) => new Array(e + 1 - s).fill(s).map((e, i) => e + i);
const filterAtInc = (arr, n) => arr.filter((e, i) => (i + 1) % n);
const makeLudic = (arr, result) => {
const iter = arr.shift();
result.push(iter);
return arr.length ? makeLudic(filterAtInc(arr, iter), result) : result;
};
const ludicResult = makeLudic(makeArr(2, n), [1]);
return ludicResult;
}