80 lines
1.5 KiB
Markdown
80 lines
1.5 KiB
Markdown
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---
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id: 594d8d0ab97724821379b1e6
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title: Averages/Mode
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challengeType: 5
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forumTopicId: 302226
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dashedName: averagesmode
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---
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# --description--
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Write a program to find the [mode](https://en.wikipedia.org/wiki/Mode (statistics) "wp: Mode (statistics)") value of a collection.
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The case where the collection is empty may be ignored. Care must be taken to handle the case where the mode is non-unique.
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If it is not appropriate or possible to support a general collection, use a vector (array), if possible. If it is not appropriate or possible to support an unspecified value type, use integers.
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# --hints--
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`mode` should be a function.
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```js
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assert(typeof mode === 'function');
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```
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`mode([1, 3, 6, 6, 6, 6, 7, 7, 12, 12, 17])` should equal `[6]`
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```js
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assert.deepEqual(mode(arr1), [6]);
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```
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`mode([1, 2, 4, 4, 1])` should equal `[1, 4]`.
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```js
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assert.deepEqual(mode(arr2).sort(), [1, 4]);
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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 arr1 = [1, 3, 6, 6, 6, 6, 7, 7, 12, 12, 17];
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const arr2 = [1, 2, 4, 4, 1];
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```
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## --seed-contents--
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```js
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function mode(arr) {
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return true;
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}
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```
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# --solutions--
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```js
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function mode(arr) {
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const counter = {};
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let result = [];
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let max = 0;
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// for (const i in arr) {
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arr.forEach(el => {
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if (!(el in counter)) {
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counter[el] = 0;
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}
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counter[el]++;
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if (counter[el] === max) {
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result.push(el);
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}
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else if (counter[el] > max) {
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max = counter[el];
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result = [el];
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}
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});
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return result;
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}
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```
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