ee1e8abd87
* feat(tools): add seed/solution restore script * chore(curriculum): remove empty sections' markers * chore(curriculum): add seed + solution to Chinese * chore: remove old formatter * fix: update getChallenges parse translated challenges separately, without reference to the source * chore(curriculum): add dashedName to English * chore(curriculum): add dashedName to Chinese * refactor: remove unused challenge property 'name' * fix: relax dashedName requirement * fix: stray tag Remove stray `pre` tag from challenge file. Signed-off-by: nhcarrigan <nhcarrigan@gmail.com> Co-authored-by: nhcarrigan <nhcarrigan@gmail.com>
110 lines
1.8 KiB
Markdown
110 lines
1.8 KiB
Markdown
---
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id: 5a23c84252665b21eecc801c
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title: Spiral matrix
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challengeType: 5
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forumTopicId: 302321
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dashedName: spiral-matrix
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---
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# --description--
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Produce a spiral array. A *spiral array* is a square arrangement of the first N<sup>2</sup> 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:
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<pre>
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0 1 2 3 4
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15 16 17 18 5
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14 23 24 19 6
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13 22 21 20 7
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12 11 10 9 8
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</pre>
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# --hints--
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`spiralArray` should be a function.
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```js
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assert(typeof spiralArray == 'function');
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```
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`spiralArray(3)` should return an array.
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```js
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assert(Array.isArray(spiralArray(3)));
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```
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`spiralArray(3)` should return `[[0, 1, 2],[7, 8, 3],[6, 5, 4]]`.
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```js
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assert.deepEqual(spiralArray(3), [
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[0, 1, 2],
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[7, 8, 3],
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[6, 5, 4]
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]);
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```
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`spiralArray(4)` should return `[[0, 1, 2, 3],[11, 12, 13, 4],[10, 15, 14, 5],[9, 8, 7, 6]]`.
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```js
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assert.deepEqual(spiralArray(4), [
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[0, 1, 2, 3],
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[11, 12, 13, 4],
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[10, 15, 14, 5],
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[9, 8, 7, 6]
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]);
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```
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`spiralArray(5)` should return `[[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]]`.
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```js
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assert.deepEqual(spiralArray(5), [
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[0, 1, 2, 3, 4],
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[15, 16, 17, 18, 5],
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[14, 23, 24, 19, 6],
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[13, 22, 21, 20, 7],
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[12, 11, 10, 9, 8]
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]);
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```
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# --seed--
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## --seed-contents--
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```js
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function spiralArray(n) {
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}
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```
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# --solutions--
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```js
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function spiralArray(n) {
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var arr = Array(n),
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x = 0,
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y = n,
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total = n * n--,
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dx = 1,
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dy = 0,
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i = 0,
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j = 0;
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while (y) arr[--y] = [];
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while (i < total) {
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arr[y][x] = i++;
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x += dx;
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y += dy;
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if (++j == n) {
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if (dy < 0) {
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x++;
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y++;
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n -= 2;
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}
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j = dx;
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dx = -dy;
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dy = j;
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j = 0;
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}
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}
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return arr;
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}
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```
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