79d9012432
* fix(curriculum): tests quotes * fix(curriculum): fill seed-teardown * fix(curriculum): fix tests and remove unneeded seed-teardown
119 lines
2.5 KiB
Markdown
119 lines
2.5 KiB
Markdown
---
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title: Zig-zag matrix
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id: 594810f028c0303b75339ad8
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challengeType: 5
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---
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## Description
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<section id='description'>
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A ''zig-zag'' array is a square arrangement of the first
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$N^2$ integers, where the
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numbers increase sequentially as you zig-zag along the array's
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<a href="https://en.wiktionary.org/wiki/antidiagonal">anti-diagonals</a>.
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For example, given '''5''', produce this array:
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<pre>
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0 1 5 6 14
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2 4 7 13 15
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3 8 12 16 21
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9 11 17 20 22
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10 18 19 23 24
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</pre>
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Write a function that takes the size of the zig-zag matrix, and returns the
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corresponding matrix as two-dimensional array.
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</section>
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## Instructions
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<section id='instructions'>
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</section>
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## Tests
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<section id='tests'>
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```yml
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tests:
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- text: ZigZagMatrix must be a function
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testString: assert.equal(typeof ZigZagMatrix, 'function', 'ZigZagMatrix must be a function');
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- text: ZigZagMatrix should return array
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testString: assert.equal(typeof ZigZagMatrix(1), 'object', 'ZigZagMatrix should return array');
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- text: ZigZagMatrix should return an array of nestes arrays
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testString: assert.equal(typeof ZigZagMatrix(1)[0], 'object', 'ZigZagMatrix should return an array of nestes arrays');
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- text: ZigZagMatrix(1) should return [[0]]
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testString: assert.deepEqual(ZigZagMatrix(1), zm1, 'ZigZagMatrix(1) should return [[0]]');
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- text: ZigZagMatrix(2) should return [[0, 1], [2, 3]]
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testString: assert.deepEqual(ZigZagMatrix(2), zm2, 'ZigZagMatrix(2) should return [[0, 1], [2, 3]]');
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- text: ZigZagMatrix(5) must return specified matrix
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testString: assert.deepEqual(ZigZagMatrix(5), zm5, 'ZigZagMatrix(5) must return specified matrix');
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```
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</section>
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## Challenge Seed
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<section id='challengeSeed'>
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<div id='js-seed'>
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```js
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function ZigZagMatrix(n) {
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// Good luck!
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return [[], []];
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}
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```
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</div>
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### After Test
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<div id='js-teardown'>
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```js
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const zm1 = [[0]];
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const zm2 = [[0, 1], [2, 3]];
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const zm5 = [
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[0, 1, 5, 6, 14],
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[2, 4, 7, 13, 15],
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[3, 8, 12, 16, 21],
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[9, 11, 17, 20, 22],
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[10, 18, 19, 23, 24]
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];
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```
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</div>
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</section>
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## Solution
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<section id='solution'>
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```js
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function ZigZagMatrix(n) {
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const mtx = [];
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for (let i = 0; i < n; i++) {
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mtx[i] = [];
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}
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let i = 1;
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let j = 1;
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for (let e = 0; e < n * n; e++) {
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mtx[i - 1][j - 1] = e;
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if ((i + j) % 2 === 0) {
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// Even stripes
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if (j < n) j++;
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else i += 2;
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if (i > 1) i--;
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} else {
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// Odd stripes
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if (i < n) i++;
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else j += 2;
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if (j > 1) j--;
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}
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}
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return mtx;
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}
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```
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</section>
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