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>
70 lines
1.2 KiB
Markdown
70 lines
1.2 KiB
Markdown
---
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id: 5900f3801000cf542c50fe93
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title: 问题20：因子数字和
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challengeType: 5
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videoUrl: ''
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dashedName: problem-20-factorial-digit-sum
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---
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# --description--
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`n` ！意味着`n` ×（ `n` - 1）×...×3×2×1例如，10！ = 10×9×...×3×2×1 = 3628800，
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和数字10中的数字之和！是3 + 6 + 2 + 8 + 8 + 0 + 0 = 27.找到数字之和`n` ！
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# --hints--
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`sumFactorialDigits(10)`应该返回27。
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```js
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assert.strictEqual(sumFactorialDigits(10), 27);
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```
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`sumFactorialDigits(25)`应该返回72。
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```js
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assert.strictEqual(sumFactorialDigits(25), 72);
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```
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`sumFactorialDigits(50)`应该返回216。
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```js
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assert.strictEqual(sumFactorialDigits(50), 216);
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```
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`sumFactorialDigits(75)`应该返回432。
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```js
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assert.strictEqual(sumFactorialDigits(75), 432);
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```
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`sumFactorialDigits(100)`应该返回648。
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```js
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assert.strictEqual(sumFactorialDigits(100), 648);
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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 sumFactorialDigits(n) {
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return n;
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}
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sumFactorialDigits(100);
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```
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# --solutions--
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```js
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let factorial = (n) => n <= 1 ? BigInt(n) : BigInt(n) * BigInt(factorial(--n));
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let sumDigits = n => n.toString().split('').map(x => parseInt(x)).reduce((a,b) => a + b);
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function sumFactorialDigits(n) {
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return sumDigits(factorial(n));
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}
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```
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