leetcode-problemset/leetcode-cn/originData/array-reduce-transformation.json

{
    "data": {
        "question": {
            "questionId": "2761",
            "questionFrontendId": "2626",
            "categoryTitle": "JavaScript",
            "boundTopicId": 2222280,
            "title": "Array Reduce Transformation",
            "titleSlug": "array-reduce-transformation",
            "content": "<p>Given an integer array&nbsp;<code>nums</code>, a reducer function&nbsp;<code>fn</code>, and an initial value&nbsp;<code>init</code>, return a&nbsp;<strong>reduced</strong>&nbsp;array.</p>\n\n<p>A&nbsp;<strong>reduced</strong>&nbsp;array is created by applying the following operation:&nbsp;<code>val = fn(init, nums[0])</code>, <code>val&nbsp;= fn(val, nums[1])</code>,&nbsp;<code>val&nbsp;= fn(val, nums[2])</code>,&nbsp;<code>...</code>&nbsp;until every element in the array has been processed. The final value of&nbsp;<code>val</code>&nbsp;is returned.</p>\n\n<p>If the length of the array is 0, it should return&nbsp;<code>init</code>.</p>\n\n<p>Please solve it without using the built-in <code>Array.reduce</code> method.</p>\n\n<p>&nbsp;</p>\n<p><strong class=\"example\">Example 1:</strong></p>\n\n<pre>\n<strong>Input:</strong> \nnums = [1,2,3,4]\nfn = function sum(accum, curr) { return accum + curr; }\ninit = 0\n<strong>Output:</strong> 10\n<strong>Explanation:</strong>\ninitially, the value is init=0.\n(0) + nums[0] = 1\n(1) + nums[1] = 3\n(3) + nums[2] = 6\n(6) + nums[3] = 10\nThe final answer is 10.\n</pre>\n\n<p><strong class=\"example\">Example 2:</strong></p>\n\n<pre>\n<strong>Input:</strong> \nnums = [1,2,3,4]\nfn = function sum(accum, curr) { return accum + curr * curr; }\ninit = 100\n<strong>Output:</strong> 130\n<strong>Explanation:</strong>\ninitially, the value is init=100.\n(100) + nums[0]^2 = 101\n(101) + nums[1]^2 = 105\n(105) + nums[2]^2 = 114\n(114) + nums[3]^2 = 130\nThe final answer is 130.\n</pre>\n\n<p><strong class=\"example\">Example 3:</strong></p>\n\n<pre>\n<strong>Input:</strong> \nnums = []\nfn = function sum(accum, curr) { return 0; }\ninit = 25\n<strong>Output:</strong> 25\n<strong>Explanation:</strong> For empty arrays, the answer is always init.\n</pre>\n\n<p>&nbsp;</p>\n<p><strong>Constraints:</strong></p>\n\n<ul>\n\t<li><code>0 &lt;= nums.length &lt;= 1000</code></li>\n\t<li><code>0 &lt;= nums[i] &lt;= 1000</code></li>\n\t<li><code>0 &lt;= init &lt;= 1000</code></li>\n</ul>\n",
            "translatedTitle": "数组归约运算",
            "translatedContent": "<p>请你编写一个函数，它的参数为一个整数数组&nbsp;<code>nums</code>&nbsp;、一个计算函数&nbsp;<code>fn</code>&nbsp;和初始值<code>init</code>&nbsp;。返回一个数组&nbsp;<strong>归约后 </strong>的值。</p>\n\n<p>你可以定义一个数组&nbsp;<strong>归约后 </strong>的值，然后应用以下操作： <code>val = fn(init, nums[0])</code>&nbsp;， <code>val = fn(val, nums[1])</code>&nbsp;， <code>val = fn(val, nums[2])</code>&nbsp;，<code>...</code>&nbsp;直到数组中的每个元素都被处理完毕。返回 <code>val</code> 的最终值。</p>\n\n<p>如果数组的长度为 0，它应该返回 <code>init</code>&nbsp;的值。</p>\n\n<p>请你在不使用内置数组方法的&nbsp;<code>Array.reduce</code>&nbsp;前提下解决这个问题。</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>\nnums = [1,2,3,4]\nfn = function sum(accum, curr) { return accum + curr; }\ninit = 0\n<strong>输出：</strong>10\n<strong>解释：</strong>\n初始值为 init=0 。\n(0) + nums[0] = 1\n(1) + nums[1] = 3\n(3) + nums[2] = 6\n(6) + nums[3] = 10\nVal 最终值为 10。\n</pre>\n\n<p><strong class=\"example\">示例 2：</strong></p>\n\n<pre>\n<strong>输入：</strong> \nnums = [1,2,3,4]\nfn = function sum(accum, curr) { return accum + curr * curr; }\ninit = 100\n<strong>输出：</strong>130\n<strong>解释：</strong>\n初始值为 init=100 。\n(100) + nums[0]^2 = 101\n(101) + nums[1]^2 = 105\n(105) + nums[2]^2 = 114\n(114) + nums[3]^2 = 130\nVal 最终值为 130。\n</pre>\n\n<p><strong class=\"example\">示例3:</strong></p>\n\n<pre>\n<strong>输入：</strong> \nnums = []\nfn = function sum(accum, curr) { return 0; }\ninit = 25\n<strong>输出：</strong>25\n<b>解释：</b>这是一个空数组，所以返回 init 。\n</pre>\n\n<p>&nbsp;</p>\n\n<p><strong>提示：</strong></p>\n\n<ul>\n\t<li><code>0 &lt;= nums.length &lt;= 1000</code></li>\n\t<li><code>0 &lt;= nums[i] &lt;= 1000</code></li>\n\t<li><code>0 &lt;= init &lt;= 1000</code></li>\n</ul>\n",
            "isPaidOnly": false,
            "difficulty": "Easy",
            "likes": 9,
            "dislikes": 0,
            "isLiked": null,
            "similarQuestions": "[]",
            "contributors": [],
            "langToValidPlayground": "{\"cpp\": true, \"java\": true, \"python\": true, \"python3\": true, \"mysql\": false, \"mssql\": false, \"oraclesql\": false, \"c\": false, \"csharp\": false, \"javascript\": false, \"typescript\": false, \"bash\": false, \"php\": false, \"swift\": false, \"kotlin\": false, \"dart\": false, \"golang\": false, \"ruby\": false, \"scala\": false, \"html\": false, \"pythonml\": false, \"rust\": false, \"racket\": false, \"erlang\": false, \"elixir\": false, \"pythondata\": false, \"react\": false, \"vanillajs\": false, \"postgresql\": false}",
            "topicTags": [],
            "companyTagStats": null,
            "codeSnippets": [
                {
                    "lang": "JavaScript",
                    "langSlug": "javascript",
                    "code": "/**\n * @param {number[]} nums\n * @param {Function} fn\n * @param {number} init\n * @return {number}\n */\nvar reduce = function(nums, fn, init) {\n    \n};",
                    "__typename": "CodeSnippetNode"
                },
                {
                    "lang": "TypeScript",
                    "langSlug": "typescript",
                    "code": "type Fn = (accum: number, curr: number) => number\n\nfunction reduce(nums: number[], fn: Fn, init: number): number {\n    \n};",
                    "__typename": "CodeSnippetNode"
                }
            ],
            "stats": "{\"totalAccepted\": \"9.2K\", \"totalSubmission\": \"11.9K\", \"totalAcceptedRaw\": 9215, \"totalSubmissionRaw\": 11950, \"acRate\": \"77.1%\"}",
            "hints": [
                "Declare a variable \"res\" and set it it equal to the initial value.",
                "Loop over each value in the array and set \"res\" = fn(res, arr[i])."
            ],
            "solution": null,
            "status": null,
            "sampleTestCase": "[1,2,3,4]\nfunction sum(accum, curr) { return accum + curr; }\n0",
            "metaData": "{\n  \"name\": \"reduce\",\n  \"params\": [\n    {\n      \"name\": \"nums\",\n      \"type\": \"integer[]\"\n    },\n    {\n      \"type\": \"string\",\n      \"name\": \"fn\"\n    },\n    {\n      \"type\": \"integer\",\n      \"name\": \"init\"\n    }\n  ],\n  \"return\": {\n    \"type\": \"integer\"\n  },\n  \"manual\": true,\n  \"languages\": [\n    \"javascript\",\n    \"typescript\"\n  ]\n}",
            "judgerAvailable": true,
            "judgeType": "large",
            "mysqlSchemas": [],
            "enableRunCode": true,
            "envInfo": "{\"javascript\":[\"JavaScript\",\"<p>\\u7248\\u672c\\uff1a<code>Node.js 16.13.2<\\/code><\\/p>\\r\\n\\r\\n<p>\\u60a8\\u7684\\u4ee3\\u7801\\u5728\\u6267\\u884c\\u65f6\\u5c06\\u5e26\\u4e0a <code>--harmony<\\/code> \\u6807\\u8bb0\\u6765\\u5f00\\u542f <a href=\\\"http:\\/\\/node.green\\/\\\" target=\\\"_blank\\\">\\u65b0\\u7248ES6\\u7279\\u6027<\\/a>\\u3002<\\/p>\\r\\n\\r\\n<p><a href=\\\"https:\\/\\/lodash.com\\\" target=\\\"_blank\\\">lodash.js<\\/a> \\u5e93\\u5df2\\u7ecf\\u9ed8\\u8ba4\\u88ab\\u5305\\u542b\\u3002<\\/p>\\r\\n\\r\\n<p> \\u5982\\u9700\\u4f7f\\u7528\\u961f\\u5217\\/\\u4f18\\u5148\\u961f\\u5217\\uff0c\\u60a8\\u53ef\\u4f7f\\u7528 <a href=\\\"https:\\/\\/github.com\\/datastructures-js\\/priority-queue\\/tree\\/fb4fdb984834421279aeb081df7af624d17c2a03\\\" target=\\\"_blank\\\"> datastructures-js\\/priority-queue@5.3.0<\\/a> \\u548c <a href=\\\"https:\\/\\/github.com\\/datastructures-js\\/queue\\/tree\\/e63563025a5a805aa16928cb53bcd517bfea9230\\\" target=\\\"_blank\\\"> datastructures-js\\/queue@4.2.1<\\/a>\\u3002<\\/p>\"],\"typescript\":[\"TypeScript\",\"<p>TypeScript 5.1.6<\\/p>\\r\\n\\r\\n<p>Compile Options: --alwaysStrict --strictBindCallApply --strictFunctionTypes --target ES2022<\\/p>\\r\\n\\r\\n<p><a href=\\\"https:\\/\\/lodash.com\\\" target=\\\"_blank\\\">lodash.js<\\/a> \\u5e93\\u5df2\\u7ecf\\u9ed8\\u8ba4\\u88ab\\u5305\\u542b\\u3002<\\/p>\\r\\n\\r\\n<p> \\u5982\\u9700\\u4f7f\\u7528\\u961f\\u5217\\/\\u4f18\\u5148\\u961f\\u5217\\uff0c\\u60a8\\u53ef\\u4f7f\\u7528 <a href=\\\"https:\\/\\/github.com\\/datastructures-js\\/priority-queue\\/tree\\/fb4fdb984834421279aeb081df7af624d17c2a03\\\" target=\\\"_blank\\\"> datastructures-js\\/priority-queue@5.3.0<\\/a> \\u548c <a href=\\\"https:\\/\\/github.com\\/datastructures-js\\/queue\\/tree\\/e63563025a5a805aa16928cb53bcd517bfea9230\\\" target=\\\"_blank\\\"> datastructures-js\\/queue@4.2.1<\\/a>\\u3002<\\/p>\"]}",
            "book": null,
            "isSubscribed": false,
            "isDailyQuestion": false,
            "dailyRecordStatus": null,
            "editorType": "CKEDITOR",
            "ugcQuestionId": null,
            "style": "LEETCODE",
            "exampleTestcases": "[1,2,3,4]\nfunction sum(accum, curr) { return accum + curr; }\n0\n[1,2,3,4]\nfunction sum(accum, curr) { return accum + curr * curr; }\n100\n[]\nfunction sum(accum, curr) { return 0; }\n25",
            "__typename": "QuestionNode"
        }
    }
}