121 lines
2.7 KiB
Markdown
121 lines
2.7 KiB
Markdown
---
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id: 56533eb9ac21ba0edf2244c6
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title: Stand in Line
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challengeType: 1
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videoUrl: 'https://scrimba.com/c/ca8Q8tP'
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forumTopicId: 18307
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localeTitle: 排队
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---
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## Description
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<section id='description'>
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在计算机科学中<dfn>队列</dfn>（queue）是一个抽象的数据结构，队列中的条目都是有秩序的。新的条目会被加到<code>队列</code>的末尾，旧的条目会从<code>队列</code>的头部被移出。
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写一个函数<code>nextInLine</code>，用一个数组(<code>arr</code>)和一个数字(<code>item</code>)作为参数。
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把数字添加到数组的结尾，然后移出数组的第一个元素。
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最后<code>nextInLine</code>函数应该返回被删除的元素。
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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: <code>nextInLine([], 5)</code>应该返回一个数字。
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testString: assert.isNumber(nextInLine([],5));
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- text: <code>nextInLine([], 1)</code>应该返回<code>1</code>。
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testString: assert(nextInLine([],1) === 1);
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- text: <code>nextInLine([2], 1)</code>应该返回<code>2</code>。
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testString: assert(nextInLine([2],1) === 2);
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- text: <code>nextInLine([5,6,7,8,9], 1)</code>应该返回<code>5</code>。
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testString: assert(nextInLine([5,6,7,8,9],1) === 5);
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- text: 在<code>nextInLine(testArr, 10)</code>执行后<code>testArr[4]</code>应该是<code>10</code>。
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testString: nextInLine(testArr, 10); assert(testArr[4] === 10);
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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 nextInLine(arr, item) {
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// Your code here
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return item; // Change this line
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}
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// Test Setup
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var testArr = [1,2,3,4,5];
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// Display Code
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console.log("Before: " + JSON.stringify(testArr));
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console.log(nextInLine(testArr, 6)); // Modify this line to test
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console.log("After: " + JSON.stringify(testArr));
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```
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</div>
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### Before Test
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<div id='js-setup'>
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```js
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var logOutput = [];
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var originalConsole = console
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function capture() {
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var nativeLog = console.log;
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console.log = function (message) {
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logOutput.push(message);
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if(nativeLog.apply) {
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nativeLog.apply(originalConsole, arguments);
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} else {
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var nativeMsg = Array.prototype.slice.apply(arguments).join(' ');
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nativeLog(nativeMsg);
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}
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};
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}
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function uncapture() {
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console.log = originalConsole.log;
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}
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capture();
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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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uncapture();
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testArr = [1,2,3,4,5];
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(function() { return logOutput.join("\n");})();
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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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var testArr = [ 1,2,3,4,5];
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function nextInLine(arr, item) {
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arr.push(item);
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return arr.shift();
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}
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```
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</section>
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