82 lines
1.8 KiB
Markdown
82 lines
1.8 KiB
Markdown
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---
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id: 5cc0bd7a49b71cb96132e54c
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title: 使用遞歸來創建一個數字序列
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challengeType: 1
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forumTopicId: 301180
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dashedName: use-recursion-to-create-a-range-of-numbers
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---
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# --description--
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接着上一個挑戰，有另外一個機會來用遞歸函數解決問題。
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# --instructions--
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已經定義好了 `rangeOfNumbers` 函數，包含兩個參數。 函數應該返回一個連續數字數組，`startNum` 參數開始 `endNum` 參數截止。 開始的數字小於或等於截止數字。 函數必需遞歸調用自身，不能使用任意形式的循環。 要考慮到 `startNum` 和 `endNum` 相同的情況。
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# --hints--
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函數應該返回一個數組。
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```js
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assert(Array.isArray(rangeOfNumbers(5, 10)));
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```
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不能包含循環語句（`for` 或者 `while` 或者高階函數比如 `forEach`、`map`、`filter` 或者 `reduce`）。
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```js
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assert(
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!code.match(/for|while|forEach|map|filter|reduce/g)
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);
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```
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`rangeOfNumbers` 應該使用遞歸函數（調用自身）來完成這個挑戰。
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```js
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assert(
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rangeOfNumbers.toString().match(/rangeOfNumbers\s*\(.+\)/)
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);
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```
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`rangeOfNumbers(1, 5)` 應該返回 `[1, 2, 3, 4, 5]`。
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```js
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assert.deepStrictEqual(rangeOfNumbers(1, 5), [1, 2, 3, 4, 5]);
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```
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`rangeOfNumbers(6, 9)` 應該返回 `[6, 7, 8, 9]`。
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```js
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assert.deepStrictEqual(rangeOfNumbers(6, 9), [6, 7, 8, 9]);
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```
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`rangeOfNumbers(4, 4)` 應該返回 `[4]`。
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```js
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assert.deepStrictEqual(rangeOfNumbers(4, 4), [4]);
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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 rangeOfNumbers(startNum, endNum) {
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return [];
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};
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```
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# --solutions--
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```js
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function rangeOfNumbers(startNum, endNum) {
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if (endNum - startNum === 0) {
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return [startNum];
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} else {
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var numbers = rangeOfNumbers(startNum, endNum - 1);
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numbers.push(endNum);
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return numbers;
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}
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}
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```
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