22afc2a0ca
Co-authored-by: Oliver Eyton-Williams <ojeytonwilliams@gmail.com> Co-authored-by: Kristofer Koishigawa <scissorsneedfoodtoo@gmail.com> Co-authored-by: Beau Carnes <beaucarnes@gmail.com>
2.2 KiB
2.2 KiB
id, title, challengeType, isHidden, forumTopicId
| id | title | challengeType | isHidden | forumTopicId |
|---|---|---|---|---|
| 5a23c84252665b21eecc801c | Spiral matrix | 5 | false | 302321 |
Description
Produce a spiral array. A spiral array is a square arrangement of the first N2 natural numbers, where the numbers increase sequentially as you go around the edges of the array spiraling inwards. For example, given 5, produce this array:
0 1 2 3 4 15 16 17 18 5 14 23 24 19 6 13 22 21 20 7 12 11 10 9 8
Instructions
Tests
tests:
- text: <code>spiralArray</code> should be a function.
testString: assert(typeof spiralArray=='function');
- text: <code>spiralArray(3)</code> should return an array.
testString: assert(Array.isArray(spiralArray(3)));
- text: <code>spiralArray(3)</code> should return <code>[[0, 1, 2],[7, 8, 3],[6, 5, 4]]</code>.
testString: assert.deepEqual(spiralArray(3), [[0, 1, 2], [7, 8, 3], [6, 5, 4]]);
- text: <code>spiralArray(4)</code> should return <code>[[0, 1, 2, 3],[11, 12, 13, 4],[10, 15, 14, 5],[9, 8, 7, 6]]</code>.
testString: assert.deepEqual(spiralArray(4), [[0, 1, 2, 3], [11, 12, 13, 4], [10, 15, 14, 5], [9, 8, 7, 6]]);
- text: <code>spiralArray(5)</code> should return <code>[[0, 1, 2, 3, 4],[15, 16, 17, 18, 5],[14, 23, 24, 19, 6],[13, 22, 21, 20, 7],[12, 11, 10, 9, 8]]</code>.
testString: assert.deepEqual(spiralArray(5), [[0, 1, 2, 3, 4], [15, 16, 17, 18, 5], [14, 23, 24, 19, 6], [13, 22, 21, 20, 7], [12, 11, 10, 9, 8]]);
Challenge Seed
function spiralArray(n) {
// Good luck!
}
Solution
function spiralArray(n) {
var arr = Array(n),
x = 0,
y = n,
total = n * n--,
dx = 1,
dy = 0,
i = 0,
j = 0;
while (y) arr[--y] = [];
while (i < total) {
arr[y][x] = i++;
x += dx;
y += dy;
if (++j == n) {
if (dy < 0) {
x++;
y++;
n -= 2;
}
j = dx;
dx = -dy;
dy = j;
j = 0;
}
}
return arr;
}