76 lines
1.3 KiB
Markdown
76 lines
1.3 KiB
Markdown
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---
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id: 594810f028c0303b75339ad2
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title: Vector cross product
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challengeType: 5
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forumTopicId: 302342
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dashedName: vector-cross-product
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---
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# --description--
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A vector is defined as having three dimensions as being represented by an ordered collection of three numbers: (X, Y, Z).
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# --instructions--
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Write a function that takes two vectors (arrays) as input and computes their cross product. Your function should return `null` on invalid inputs such as vectors of different lengths.
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# --hints--
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dotProduct should be a function.
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```js
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assert.equal(typeof crossProduct, 'function');
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```
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dotProduct() should return null.
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```js
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assert.equal(crossProduct(), null);
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```
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crossProduct([1, 2, 3], [4, 5, 6]) should return [-3, 6, -3].
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```js
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assert.deepEqual(res12, exp12);
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```
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# --seed--
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## --after-user-code--
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```js
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const tv1 = [1, 2, 3];
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const tv2 = [4, 5, 6];
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const res12 = crossProduct(tv1, tv2);
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const exp12 = [-3, 6, -3];
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```
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## --seed-contents--
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```js
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function crossProduct(a, b) {
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}
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```
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# --solutions--
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```js
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function crossProduct(a, b) {
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if (!a || !b) {
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return null;
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}
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// Check lengths
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if (a.length !== 3 || b.length !== 3) {
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return null;
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}
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return [
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(a[1] * b[2]) - (a[2] * b[1]),
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(a[2] * b[0]) - (a[0] * b[2]),
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(a[0] * b[1]) - (a[1] * b[0])
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];
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}
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```
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