{ "data": { "question": { "questionId": "2397", "questionFrontendId": "2320", "categoryTitle": "Algorithms", "boundTopicId": 1621114, "title": "Count Number of Ways to Place Houses", "titleSlug": "count-number-of-ways-to-place-houses", "content": "

There is a street with n * 2 plots, where there are n plots on each side of the street. The plots on each side are numbered from 1 to n. On each plot, a house can be placed.

\n\n

Return the number of ways houses can be placed such that no two houses are adjacent to each other on the same side of the street. Since the answer may be very large, return it modulo 109 + 7.

\n\n

Note that if a house is placed on the ith plot on one side of the street, a house can also be placed on the ith plot on the other side of the street.

\n\n

 

\n

Example 1:

\n\n
\nInput: n = 1\nOutput: 4\nExplanation: \nPossible arrangements:\n1. All plots are empty.\n2. A house is placed on one side of the street.\n3. A house is placed on the other side of the street.\n4. Two houses are placed, one on each side of the street.\n
\n\n

Example 2:

\n\"\"\n
\nInput: n = 2\nOutput: 9\nExplanation: The 9 possible arrangements are shown in the diagram above.\n
\n\n

 

\n

Constraints:

\n\n\n", "translatedTitle": "统计放置房子的方式数", "translatedContent": "

一条街道上共有 n * 2地块 ,街道的两侧各有 n 个地块。每一边的地块都按从 1n 编号。每个地块上都可以放置一所房子。

\n\n

现要求街道同一侧不能存在两所房子相邻的情况,请你计算并返回放置房屋的方式数目。由于答案可能很大,需要对 109 + 7 取余后再返回。

\n\n

注意,如果一所房子放置在这条街某一侧上的第 i 个地块,不影响在另一侧的第 i 个地块放置房子。

\n\n

 

\n\n

示例 1:

\n\n
输入:n = 1\n输出:4\n解释:\n可能的放置方式:\n1. 所有地块都不放置房子。\n2. 一所房子放在街道的某一侧。\n3. 一所房子放在街道的另一侧。\n4. 放置两所房子,街道两侧各放置一所。\n
\n\n

示例 2:

\n\"\"\n
输入:n = 2\n输出:9\n解释:如上图所示,共有 9 种可能的放置方式。\n
\n\n

 

\n\n

提示:

\n\n\n", "isPaidOnly": false, "difficulty": "Medium", "likes": 64, "dislikes": 0, "isLiked": null, "similarQuestions": "[{\"title\": \"Climbing Stairs\", \"titleSlug\": \"climbing-stairs\", \"difficulty\": \"Easy\", \"translatedTitle\": \"\\u722c\\u697c\\u68af\", \"isPaidOnly\": false}, {\"title\": \"House Robber\", \"titleSlug\": \"house-robber\", \"difficulty\": \"Medium\", \"translatedTitle\": \"\\u6253\\u5bb6\\u52ab\\u820d\", \"isPaidOnly\": false}]", "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, \"cangjie\": false}", "topicTags": [ { "name": "Dynamic Programming", "slug": "dynamic-programming", "translatedName": "动态规划", "__typename": "TopicTagNode" } ], "companyTagStats": null, "codeSnippets": [ { "lang": "C++", "langSlug": "cpp", "code": "class Solution {\npublic:\n int countHousePlacements(int n) {\n \n }\n};", "__typename": "CodeSnippetNode" }, { "lang": "Java", "langSlug": "java", "code": "class Solution {\n public int countHousePlacements(int n) {\n \n }\n}", "__typename": "CodeSnippetNode" }, { "lang": "Python", "langSlug": "python", "code": "class Solution(object):\n def countHousePlacements(self, n):\n \"\"\"\n :type n: int\n :rtype: int\n \"\"\"\n ", "__typename": "CodeSnippetNode" }, { "lang": "Python3", "langSlug": "python3", "code": "class Solution:\n def countHousePlacements(self, n: int) -> int:\n ", "__typename": "CodeSnippetNode" }, { "lang": "C", "langSlug": "c", "code": "int countHousePlacements(int n) {\n \n}", "__typename": "CodeSnippetNode" }, { "lang": "C#", "langSlug": "csharp", "code": "public class Solution {\n public int CountHousePlacements(int n) {\n \n }\n}", "__typename": "CodeSnippetNode" }, { "lang": "JavaScript", "langSlug": "javascript", "code": "/**\n * @param {number} n\n * @return {number}\n */\nvar countHousePlacements = function(n) {\n \n};", "__typename": "CodeSnippetNode" }, { "lang": "TypeScript", "langSlug": "typescript", "code": "function countHousePlacements(n: number): number {\n \n};", "__typename": "CodeSnippetNode" }, { "lang": "PHP", "langSlug": "php", "code": "class Solution {\n\n /**\n * @param Integer $n\n * @return Integer\n */\n function countHousePlacements($n) {\n \n }\n}", "__typename": "CodeSnippetNode" }, { "lang": "Swift", "langSlug": "swift", "code": "class Solution {\n func countHousePlacements(_ n: Int) -> Int {\n \n }\n}", "__typename": "CodeSnippetNode" }, { "lang": "Kotlin", "langSlug": "kotlin", "code": "class Solution {\n fun countHousePlacements(n: Int): Int {\n \n }\n}", "__typename": "CodeSnippetNode" }, { "lang": "Dart", "langSlug": "dart", "code": "class Solution {\n int countHousePlacements(int n) {\n \n }\n}", "__typename": "CodeSnippetNode" }, { "lang": "Go", "langSlug": "golang", "code": "func countHousePlacements(n int) int {\n \n}", "__typename": "CodeSnippetNode" }, { "lang": "Ruby", "langSlug": "ruby", "code": "# @param {Integer} n\n# @return {Integer}\ndef count_house_placements(n)\n \nend", "__typename": "CodeSnippetNode" }, { "lang": "Scala", "langSlug": "scala", "code": "object Solution {\n def countHousePlacements(n: Int): Int = {\n \n }\n}", "__typename": "CodeSnippetNode" }, { "lang": "Rust", "langSlug": "rust", "code": "impl Solution {\n pub fn count_house_placements(n: i32) -> i32 {\n \n }\n}", "__typename": "CodeSnippetNode" }, { "lang": "Racket", "langSlug": "racket", "code": "(define/contract (count-house-placements n)\n (-> exact-integer? exact-integer?)\n )", "__typename": "CodeSnippetNode" }, { "lang": "Erlang", "langSlug": "erlang", "code": "-spec count_house_placements(N :: integer()) -> integer().\ncount_house_placements(N) ->\n .", "__typename": "CodeSnippetNode" }, { "lang": "Elixir", "langSlug": "elixir", "code": "defmodule Solution do\n @spec count_house_placements(n :: integer) :: integer\n def count_house_placements(n) do\n \n end\nend", "__typename": "CodeSnippetNode" }, { "lang": "Cangjie", "langSlug": "cangjie", "code": "class Solution {\n func countHousePlacements(n: Int64): Int64 {\n\n }\n}", "__typename": "CodeSnippetNode" } ], "stats": "{\"totalAccepted\": \"17.4K\", \"totalSubmission\": \"38.5K\", \"totalAcceptedRaw\": 17420, \"totalSubmissionRaw\": 38520, \"acRate\": \"45.2%\"}", "hints": [ "Try coming up with a DP solution for one side of the street.", "The DP for one side of the street will bear resemblance to the Fibonacci sequence.", "The number of different arrangements on both side of the street is the same." ], "solution": null, "status": null, "sampleTestCase": "1", "metaData": "{\n \"name\": \"countHousePlacements\",\n \"params\": [\n {\n \"name\": \"n\",\n \"type\": \"integer\"\n }\n ],\n \"return\": {\n \"type\": \"integer\"\n }\n}", "judgerAvailable": true, "judgeType": "large", "mysqlSchemas": [], "enableRunCode": true, "envInfo": "{\"cpp\":[\"C++\",\"

\\u7248\\u672c\\uff1aclang 19<\\/code> \\u91c7\\u7528\\u6700\\u65b0 C++ 23 \\u6807\\u51c6\\uff0c\\u5e76\\u4f7f\\u7528 GCC 14 \\u63d0\\u4f9b\\u7684 libstdc++<\\/code>\\u3002<\\/p>\\r\\n\\r\\n

\\u7f16\\u8bd1\\u65f6\\uff0c\\u5c06\\u4f1a\\u91c7\\u7528 -O2<\\/code> \\u7ea7\\u4f18\\u5316\\uff0c\\u5e76\\u63d0\\u4f9b -gline-tables-only<\\/code> \\u53c2\\u6570\\u3002AddressSanitizer<\\/a> \\u4e5f\\u88ab\\u5f00\\u542f\\u6765\\u68c0\\u6d4b out-of-bounds<\\/code> \\u548c use-after-free<\\/code> \\u9519\\u8bef\\u3002<\\/p>\\r\\n\\r\\n

\\u4e3a\\u4e86\\u4f7f\\u7528\\u65b9\\u4fbf\\uff0c\\u5927\\u90e8\\u5206\\u6807\\u51c6\\u5e93\\u7684\\u5934\\u6587\\u4ef6\\u5df2\\u7ecf\\u88ab\\u81ea\\u52a8\\u5bfc\\u5165\\u3002<\\/p>\"],\"java\":[\"Java\",\"

\\u7248\\u672c\\uff1aOpenJDK 21<\\/code>\\u3002\\u4f7f\\u7528\\u7f16\\u8bd1\\u53c2\\u6570 --enable-preview --release 21<\\/code><\\/p>\\r\\n\\r\\n

\\u4e3a\\u4e86\\u65b9\\u4fbf\\u8d77\\u89c1\\uff0c\\u5927\\u90e8\\u5206\\u6807\\u51c6\\u5e93\\u7684\\u5934\\u6587\\u4ef6\\u5df2\\u88ab\\u5bfc\\u5165\\u3002<\\/p>\\r\\n\\r\\n

\\u5305\\u542b Pair \\u7c7b: https:\\/\\/docs.oracle.com\\/javase\\/8\\/javafx\\/api\\/javafx\\/util\\/Pair.html <\\/p>\"],\"python\":[\"Python\",\"

\\u7248\\u672c\\uff1a Python 2.7.18<\\/code><\\/p>\\r\\n\\r\\n

\\u4e3a\\u4e86\\u65b9\\u4fbf\\u8d77\\u89c1\\uff0c\\u5927\\u90e8\\u5206\\u5e38\\u7528\\u5e93\\u5df2\\u7ecf\\u88ab\\u81ea\\u52a8 \\u5bfc\\u5165\\uff0c\\u5982\\uff1aarray<\\/a>, bisect<\\/a>, collections<\\/a>\\u3002\\u5982\\u679c\\u60a8\\u9700\\u8981\\u4f7f\\u7528\\u5176\\u4ed6\\u5e93\\u51fd\\u6570\\uff0c\\u8bf7\\u81ea\\u884c\\u5bfc\\u5165\\u3002<\\/p>\\r\\n\\r\\n

\\u6ce8\\u610f Python 2.7 \\u5df2\\u4e0d\\u518d\\u7ef4\\u62a4<\\/a>\\u3002 \\u5982\\u60f3\\u4f7f\\u7528\\u6700\\u65b0\\u7248\\u7684Python\\uff0c\\u8bf7\\u9009\\u62e9Python 3\\u3002<\\/p>\"],\"c\":[\"C\",\"

\\u7248\\u672c\\uff1aGCC 14<\\/code>\\uff0c\\u91c7\\u7528 GNU11 \\u6807\\u51c6\\u3002<\\/p>\\r\\n\\r\\n

\\u7f16\\u8bd1\\u65f6\\uff0c\\u5c06\\u4f1a\\u91c7\\u7528 -O2<\\/code> \\u7ea7\\u4f18\\u5316\\uff0c\\u5e76\\u63d0\\u4f9b -g1<\\/code> \\u53c2\\u6570\\u3002 AddressSanitizer<\\/a> \\u4e5f\\u88ab\\u5f00\\u542f\\u6765\\u68c0\\u6d4b out-of-bounds<\\/code> \\u548c use-after-free<\\/code> \\u9519\\u8bef\\u3002<\\/p>\\r\\n\\r\\n

\\u4e3a\\u4e86\\u4f7f\\u7528\\u65b9\\u4fbf\\uff0c\\u5927\\u90e8\\u5206\\u6807\\u51c6\\u5e93\\u7684\\u5934\\u6587\\u4ef6\\u5df2\\u7ecf\\u88ab\\u81ea\\u52a8\\u5bfc\\u5165\\u3002<\\/p>\\r\\n\\r\\n

\\u5982\\u60f3\\u4f7f\\u7528\\u54c8\\u5e0c\\u8868\\u8fd0\\u7b97, \\u60a8\\u53ef\\u4ee5\\u4f7f\\u7528 uthash<\\/a>\\u3002 \\\"uthash.h\\\"\\u5df2\\u7ecf\\u9ed8\\u8ba4\\u88ab\\u5bfc\\u5165\\u3002\\u8bf7\\u770b\\u5982\\u4e0b\\u793a\\u4f8b:<\\/p>\\r\\n\\r\\n

1. \\u5f80\\u54c8\\u5e0c\\u8868\\u4e2d\\u6dfb\\u52a0\\u4e00\\u4e2a\\u5bf9\\u8c61\\uff1a<\\/b>\\r\\n

\\r\\nstruct hash_entry {\\r\\n    int id;            \\/* we'll use this field as the key *\\/\\r\\n    char name[10];\\r\\n    UT_hash_handle hh; \\/* makes this structure hashable *\\/\\r\\n};\\r\\n\\r\\nstruct hash_entry *users = NULL;\\r\\n\\r\\nvoid add_user(struct hash_entry *s) {\\r\\n    HASH_ADD_INT(users, id, s);\\r\\n}\\r\\n<\\/pre>\\r\\n<\\/p>\\r\\n\\r\\n

2. \\u5728\\u54c8\\u5e0c\\u8868\\u4e2d\\u67e5\\u627e\\u4e00\\u4e2a\\u5bf9\\u8c61\\uff1a<\\/b>\\r\\n

\\r\\nstruct hash_entry *find_user(int user_id) {\\r\\n    struct hash_entry *s;\\r\\n    HASH_FIND_INT(users, &user_id, s);\\r\\n    return s;\\r\\n}\\r\\n<\\/pre>\\r\\n<\\/p>\\r\\n\\r\\n

3. \\u4ece\\u54c8\\u5e0c\\u8868\\u4e2d\\u5220\\u9664\\u4e00\\u4e2a\\u5bf9\\u8c61\\uff1a<\\/b>\\r\\n

\\r\\nvoid delete_user(struct hash_entry *user) {\\r\\n    HASH_DEL(users, user);  \\r\\n}\\r\\n<\\/pre>\\r\\n<\\/p>\"],\"csharp\":[\"C#\",\"

C# 13<\\/a> \\u8fd0\\u884c\\u5728 .NET 9 \\u4e0a<\\/p>\"],\"javascript\":[\"JavaScript\",\"

\\u7248\\u672c\\uff1aNode.js 20.10.0<\\/code><\\/p>\\r\\n\\r\\n

\\u60a8\\u7684\\u4ee3\\u7801\\u5728\\u6267\\u884c\\u65f6\\u5c06\\u5e26\\u4e0a --harmony<\\/code> \\u6807\\u8bb0\\u6765\\u5f00\\u542f \\u65b0\\u7248ES6\\u7279\\u6027<\\/a>\\u3002<\\/p>\\r\\n\\r\\n

lodash.js<\\/a> \\u5e93\\u5df2\\u7ecf\\u9ed8\\u8ba4\\u88ab\\u5305\\u542b\\u3002<\\/p>\\r\\n\\r\\n

\\u5982\\u9700\\u4f7f\\u7528\\u961f\\u5217\\/\\u4f18\\u5148\\u961f\\u5217\\uff0c\\u60a8\\u53ef\\u4f7f\\u7528 datastructures-js\\/priority-queue@5.4.0<\\/a>\\uff0c datastructures-js\\/queue@4.2.3<\\/a> \\u4ee5\\u53ca datastructures-js\\/deque@1.0.4<\\/a>\\u3002<\\/p>\"],\"ruby\":[\"Ruby\",\"

\\u4f7f\\u7528 Ruby 3.2<\\/code> \\u6267\\u884c<\\/p>\\r\\n\\r\\n

\\u4e00\\u4e9b\\u5e38\\u7528\\u7684\\u6570\\u636e\\u7ed3\\u6784\\u5df2\\u5728 Algorithms \\u6a21\\u5757\\u4e2d\\u63d0\\u4f9b\\uff1ahttps:\\/\\/www.rubydoc.info\\/github\\/kanwei\\/algorithms\\/Algorithms<\\/p>\"],\"swift\":[\"Swift\",\"

\\u7248\\u672c\\uff1aSwift 6.0<\\/code><\\/p>\\r\\n\\r\\n

\\u60a8\\u53ef\\u4ee5\\u4f7f\\u7528 swift-algorithms 1.2.0<\\/a>\\uff0cswift-collections 1.1.4<\\/a> \\u548c swift-numerics 1.0.2<\\/a><\\/p>\\r\\n\\r\\n

\\u6211\\u4eec\\u901a\\u5e38\\u4fdd\\u8bc1\\u66f4\\u65b0\\u5230 Apple\\u653e\\u51fa\\u7684\\u6700\\u65b0\\u7248Swift<\\/a>\\u3002\\u5982\\u679c\\u60a8\\u53d1\\u73b0Swift\\u4e0d\\u662f\\u6700\\u65b0\\u7248\\u7684\\uff0c\\u8bf7\\u8054\\u7cfb\\u6211\\u4eec\\uff01\\u6211\\u4eec\\u5c06\\u5c3d\\u5feb\\u66f4\\u65b0\\u3002<\\/p>\"],\"golang\":[\"Go\",\"

\\u7248\\u672c\\uff1aGo 1.23<\\/code><\\/p>\\r\\n\\r\\n

\\u652f\\u6301 https:\\/\\/pkg.go.dev\\/github.com\\/emirpasic\\/gods@v1.18.1<\\/a> \\u548c https:\\/\\/pkg.go.dev\\/github.com\\/emirpasic\\/gods\\/v2@v2.0.0-alpha<\\/a> \\u7b2c\\u4e09\\u65b9\\u5e93\\u3002<\\/p>\"],\"python3\":[\"Python3\",\"

\\u7248\\u672c\\uff1aPython 3.11<\\/code><\\/p>\\r\\n\\r\\n

\\u4e3a\\u4e86\\u65b9\\u4fbf\\u8d77\\u89c1\\uff0c\\u5927\\u90e8\\u5206\\u5e38\\u7528\\u5e93\\u5df2\\u7ecf\\u88ab\\u81ea\\u52a8 \\u5bfc\\u5165\\uff0c\\u5982array<\\/a>, bisect<\\/a>, collections<\\/a>\\u3002 \\u5982\\u679c\\u60a8\\u9700\\u8981\\u4f7f\\u7528\\u5176\\u4ed6\\u5e93\\u51fd\\u6570\\uff0c\\u8bf7\\u81ea\\u884c\\u5bfc\\u5165\\u3002<\\/p>\\r\\n\\r\\n

\\u5982\\u9700\\u4f7f\\u7528 Map\\/TreeMap \\u6570\\u636e\\u7ed3\\u6784\\uff0c\\u60a8\\u53ef\\u4f7f\\u7528 sortedcontainers<\\/a> \\u5e93\\u3002<\\/p>\"],\"scala\":[\"Scala\",\"

\\u7248\\u672c\\uff1aScala 3.3.1<\\/code><\\/p>\"],\"kotlin\":[\"Kotlin\",\"

\\u7248\\u672c\\uff1aKotlin 1.9.0<\\/code><\\/p>\\r\\n\\r\\n

\\u6211\\u4eec\\u4f7f\\u7528\\u7684\\u662f JetBrains \\u63d0\\u4f9b\\u7684 experimental compiler\\u3002\\u5982\\u679c\\u60a8\\u8ba4\\u4e3a\\u60a8\\u9047\\u5230\\u4e86\\u7f16\\u8bd1\\u5668\\u76f8\\u5173\\u7684\\u95ee\\u9898\\uff0c\\u8bf7\\u5411\\u6211\\u4eec\\u53cd\\u9988<\\/p>\"],\"rust\":[\"Rust\",\"

\\u7248\\u672c\\uff1arust 1.79.0<\\/code><\\/p>\\r\\n\\r\\n

\\u652f\\u6301 crates.io \\u7684 rand<\\/a> \\u548c regex<\\/a><\\/p>\"],\"php\":[\"PHP\",\"

PHP 8.2<\\/code>.<\\/p>\\r\\n\\r\\n

With bcmath module.<\\/p>\"],\"typescript\":[\"TypeScript\",\"

TypeScript 5.1.6<\\/p>\\r\\n\\r\\n

Compile Options: --alwaysStrict --strictBindCallApply --strictFunctionTypes --target ES2022<\\/p>\\r\\n\\r\\n

lodash.js<\\/a> \\u5e93\\u5df2\\u7ecf\\u9ed8\\u8ba4\\u88ab\\u5305\\u542b\\u3002<\\/p>\\r\\n\\r\\n

\\u5982\\u9700\\u4f7f\\u7528\\u961f\\u5217\\/\\u4f18\\u5148\\u961f\\u5217\\uff0c\\u60a8\\u53ef\\u4f7f\\u7528 datastructures-js\\/priority-queue@5.4.0<\\/a>\\uff0c datastructures-js\\/queue@4.2.3<\\/a> \\u4ee5\\u53ca datastructures-js\\/deque@1.0.4<\\/a>\\u3002<\\/p>\"],\"racket\":[\"Racket\",\"

Racket CS<\\/a> v8.15<\\/p>\\r\\n\\r\\n

\\u4f7f\\u7528 #lang racket<\\/p>\\r\\n\\r\\n

\\u5df2\\u9884\\u5148 (require data\\/gvector data\\/queue data\\/order data\\/heap). \\u82e5\\u9700\\u4f7f\\u7528\\u5176\\u5b83\\u6570\\u636e\\u7ed3\\u6784\\uff0c\\u53ef\\u81ea\\u884c require\\u3002<\\/p>\"],\"erlang\":[\"Erlang\",\"Erlang\\/OTP 26\"],\"elixir\":[\"Elixir\",\"Elixir 1.17 with Erlang\\/OTP 26\"],\"dart\":[\"Dart\",\"

Dart 3.2\\u3002\\u60a8\\u53ef\\u4ee5\\u4f7f\\u7528 collection<\\/a> \\u5305<\\/p>\\r\\n\\r\\n

\\u60a8\\u7684\\u4ee3\\u7801\\u5c06\\u4f1a\\u88ab\\u4e0d\\u7f16\\u8bd1\\u76f4\\u63a5\\u8fd0\\u884c<\\/p>\"],\"cangjie\":[\"Cangjie\",\"

\\u7248\\u672c\\uff1a0.53.11 (cjnative)<\\/p>\\r\\n\\r\\n

\\u7f16\\u8bd1\\u53c2\\u6570\\uff1a-O2 --disable-reflection<\\/code><\\/p>\\r\\n\\r\\n

\\u5feb\\u901f\\u5165\\u95e8\\u8bf7\\u67e5\\u9605\\u300c\\u4ed3\\u9889\\u7f16\\u7a0b\\u8bed\\u8a00\\u5f00\\u53d1\\u6307\\u5357\\u300d<\\/a><\\/p>\"]}", "book": null, "isSubscribed": false, "isDailyQuestion": false, "dailyRecordStatus": null, "editorType": "CKEDITOR", "ugcQuestionId": null, "style": "LEETCODE", "exampleTestcases": "1\n2", "__typename": "QuestionNode" } } }