leetcode-problemset/leetcode-cn/originData/function-composition.json

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        "question": {
            "questionId": "2741",
            "questionFrontendId": "2629",
            "categoryTitle": "JavaScript",
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            "title": "Function Composition",
            "titleSlug": "function-composition",
            "content": "<p>Given an array of functions&nbsp;<code>[f<span style=\"font-size: 10.8333px;\">1</span>, f<sub>2</sub>, f<sub>3</sub>,&nbsp;..., f<sub>n</sub>]</code>, return&nbsp;a new function&nbsp;<code>fn</code>&nbsp;that is the <strong>function&nbsp;composition</strong> of the array of functions.</p>\n\n<p>The&nbsp;<strong>function&nbsp;composition</strong>&nbsp;of&nbsp;<code>[f(x), g(x), h(x)]</code>&nbsp;is&nbsp;<code>fn(x) = f(g(h(x)))</code>.</p>\n\n<p>The&nbsp;<strong>function&nbsp;composition</strong>&nbsp;of an empty list of functions is the&nbsp;<strong>identity function</strong>&nbsp;<code>f(x) = x</code>.</p>\n\n<p>You may assume each&nbsp;function&nbsp;in the array accepts one integer as input&nbsp;and returns one integer as output.</p>\n\n<p>&nbsp;</p>\n<p><strong class=\"example\">Example 1:</strong></p>\n\n<pre>\n<strong>Input:</strong> functions = [x =&gt; x + 1, x =&gt; x * x, x =&gt; 2 * x], x = 4\n<strong>Output:</strong> 65\n<strong>Explanation:</strong>\nEvaluating from right to left ...\nStarting with x = 4.\n2 * (4) = 8\n(8) * (8) = 64\n(64) + 1 = 65\n</pre>\n\n<p><strong class=\"example\">Example 2:</strong></p>\n\n<pre>\n<strong>Input:</strong> functions = [x =&gt; 10 * x, x =&gt; 10 * x, x =&gt; 10 * x], x = 1\n<strong>Output:</strong> 1000\n<strong>Explanation:</strong>\nEvaluating from right to left ...\n10 * (1) = 10\n10 * (10) = 100\n10 * (100) = 1000\n</pre>\n\n<p><strong class=\"example\">Example 3:</strong></p>\n\n<pre>\n<strong>Input:</strong> functions = [], x = 42\n<strong>Output:</strong> 42\n<strong>Explanation:</strong>\nThe composition of zero functions is the identity function</pre>\n\n<p>&nbsp;</p>\n<p><strong>Constraints:</strong></p>\n\n<ul>\n\t<li><code><font face=\"monospace\">-1000 &lt;= x &lt;= 1000</font></code></li>\n\t<li><code><font face=\"monospace\">0 &lt;= functions.length &lt;= 1000</font></code></li>\n\t<li>all functions accept and return a single integer</li>\n</ul>\n",
            "translatedTitle": "复合函数",
            "translatedContent": "<p>请你编写一个函数，它接收一个函数数组 <code>[f<sub>1</sub>, f<sub>2</sub>, f<sub>3</sub>，…， f<sub>n</sub>]</code> ，并返回一个新的函数 <code>fn</code>&nbsp;，它是函数数组的 <strong>复合函数</strong> 。</p>\n\n<p><code>[f(x)， g(x)， h(x)]</code> 的 <strong>复合函数</strong> 为 <code>fn(x) = f(g(h(x)))</code>&nbsp;。</p>\n\n<p>一个空函数列表的 <strong>复合函数</strong> 是 <strong>恒等函数</strong> <code>f(x) = x</code> 。</p>\n\n<p>你可以假设数组中的每个函数接受一个整型参数作为输入，并返回一个整型作为输出。</p>\n\n<p>&nbsp;</p>\n\n<p><strong class=\"example\">示例 1：</strong></p>\n\n<pre>\n<strong>输入：</strong>functions = [x =&gt; x + 1, x =&gt; x * x, x =&gt; 2 * x], x = 4\n<b>输出：</b>65\n<strong>解释：</strong>\n从右向左计算......\nStarting with x = 4.\n2 * (4) = 8\n(8) * (8) = 64\n(64) + 1 = 65\n</pre>\n\n<p><strong class=\"example\">示例 2：</strong></p>\n\n<pre>\n<b>输出：</b>functions = [x =&gt; 10 * x, x =&gt; 10 * x, x =&gt; 10 * x], x = 1\n<b>输入：</b>1000\n<strong>解释：</strong>\n从右向左计算......\n10 * (1) = 10\n10 * (10) = 100\n10 * (100) = 1000\n</pre>\n\n<p><strong class=\"example\">示例 3：</strong></p>\n\n<pre>\n<b>输入：</b>functions = [], x = 42\n<b>输出：</b>42\n<strong>解释：</strong>\n空函数列表的复合函数就是恒等函数</pre>\n\n<p>&nbsp;</p>\n\n<p><strong>提示：</strong></p>\n\n<ul>\n\t<li><code><font face=\"monospace\">-1000 &lt;= x &lt;= 1000</font></code></li>\n\t<li><code><font face=\"monospace\">0 &lt;= functions.length &lt;= 1000</font></code></li>\n\t<li><font face=\"monospace\">所有函数都接受并返回一个整型</font></li>\n</ul>\n",
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                    "code": "/**\n * @param {Function[]} functions\n * @return {Function}\n */\nvar compose = function(functions) {\n    \n\treturn function(x) {\n        \n    }\n};\n\n/**\n * const fn = compose([x => x + 1, x => 2 * x])\n * fn(4) // 9\n */",
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                    "code": "type F = (x: number) => number;\n\nfunction compose(functions: F[]): F {\n    \n\treturn function(x) {\n        \n    }\n};\n\n/**\n * const fn = compose([x => x + 1, x => 2 * x])\n * fn(4) // 9\n */",
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            "hints": [
                "Start by returning a function that takes in a number and returns a number.",
                "Call each of the functions in the correct order. Each time passing the output of the previous function into the next function."
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