146 lines
2.7 KiB
Markdown
146 lines
2.7 KiB
Markdown
---
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id: 5a23c84252665b21eecc801d
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title: Split a character string based on change of character
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challengeType: 5
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forumTopicId: 302322
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dashedName: split-a-character-string-based-on-change-of-character
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---
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# --description--
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Split a (character) string into comma (plus a blank) delimited strings based on a change of character (left to right). Blanks should be treated as any other character (except they are problematic to display clearly). The same applies to commas. For instance, the string:
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<pre>
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"gHHH5YY++///\\"
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</pre>
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should be split as:
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<pre>
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["g", "HHH", "5", "YY", "++", "///", "\\" ];
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</pre>
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# --hints--
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`split` should be a function.
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```js
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assert(typeof split == 'function');
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```
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`split("hello")` should return an array.
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```js
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assert(Array.isArray(split('hello')));
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```
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`split("hello")` should return `["h", "e", "ll", "o"]`.
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```js
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assert.deepEqual(split('hello'), ['h', 'e', 'll', 'o']);
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```
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`split("commission")` should return `["c", "o", "mm", "i", "ss", "i", "o", "n"]`.
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```js
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assert.deepEqual(split('commission'), [
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'c',
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'o',
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'mm',
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'i',
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'ss',
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'i',
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'o',
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'n'
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]);
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```
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`split("ssss----====llloooo")` should return `["ssss", "----", "====", "lll", "oooo"]`.
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```js
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assert.deepEqual(split('ssss----====llloooo'), [
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'ssss',
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'----',
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'====',
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'lll',
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'oooo'
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]);
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```
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`split("sssmmmaaammmaaat")` should return `["sss", "mmm", "aaa", "mmm", "aaa", "t"]`.
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```js
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assert.deepEqual(split('sssmmmaaammmaaat'), [
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'sss',
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'mmm',
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'aaa',
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'mmm',
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'aaa',
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't'
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]);
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```
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`split("gHHH5YY++///\\")` should return `["g", "HHH", "5", "YY", "++", "///", "\\"]`.
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```js
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assert.deepEqual(split('gHHH5YY++///\\'), [
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'g',
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'HHH',
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'5',
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'YY',
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'++',
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'///',
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'\\'
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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 split(str) {
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}
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```
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# --solutions--
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```js
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function split(str) {
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const concat = xs =>
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xs.length > 0
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? (() => {
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const unit = typeof xs[0] === 'string' ? '' : [];
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return unit.concat.apply(unit, xs);
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})()
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: [];
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const group = xs => groupBy((a, b) => a === b, xs);
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const groupBy = (f, xs) => {
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const dct = xs.slice(1).reduce(
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(a, x) => {
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const h = a.active.length > 0 ? a.active[0] : undefined,
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blnGroup = h !== undefined && f(h, x);
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return {
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active: blnGroup ? a.active.concat([x]) : [x],
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sofar: blnGroup ? a.sofar : a.sofar.concat([a.active])
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};
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},
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{
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active: xs.length > 0 ? [xs[0]] : [],
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sofar: []
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}
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);
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return dct.sofar.concat(dct.active.length > 0 ? [dct.active] : []);
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};
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const map = (f, xs) => xs.map(f);
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const stringChars = s => s.split('');
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return map(concat, group(stringChars(str)));
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}
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```
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