{ "data": { "question": { "questionId": "2178", "questionFrontendId": "2069", "boundTopicId": null, "title": "Walking Robot Simulation II", "titleSlug": "walking-robot-simulation-ii", "content": "

A width x height grid is on an XY-plane with the bottom-left cell at (0, 0) and the top-right cell at (width - 1, height - 1). The grid is aligned with the four cardinal directions ("North", "East", "South", and "West"). A robot is initially at cell (0, 0) facing direction "East".

\n\n

The robot can be instructed to move for a specific number of steps. For each step, it does the following.

\n\n
    \n\t
  1. Attempts to move forward one cell in the direction it is facing.
    2. \n\t
  2. If the cell the robot is moving to is out of bounds, the robot instead turns 90 degrees counterclockwise and retries the step.
    3. \n
\n\n

After the robot finishes moving the number of steps required, it stops and awaits the next instruction.

\n\n

Implement the Robot class:

\n\n\n\n

 

\n

Example 1:

\n\"example-1\"\n
\nInput\n["Robot", "move", "move", "getPos", "getDir", "move", "move", "move", "getPos", "getDir"]\n[[6, 3], [2], [2], [], [], [2], [1], [4], [], []]\nOutput\n[null, null, null, [4, 0], "East", null, null, null, [1, 2], "West"]\n\nExplanation\nRobot robot = new Robot(6, 3); // Initialize the grid and the robot at (0, 0) facing East.\nrobot.move(2);  // It moves two steps East to (2, 0), and faces East.\nrobot.move(2);  // It moves two steps East to (4, 0), and faces East.\nrobot.getPos(); // return [4, 0]\nrobot.getDir(); // return "East"\nrobot.move(2);  // It moves one step East to (5, 0), and faces East.\n                // Moving the next step East would be out of bounds, so it turns and faces North.\n                // Then, it moves one step North to (5, 1), and faces North.\nrobot.move(1);  // It moves one step North to (5, 2), and faces North (not West).\nrobot.move(4);  // Moving the next step North would be out of bounds, so it turns and faces West.\n                // Then, it moves four steps West to (1, 2), and faces West.\nrobot.getPos(); // return [1, 2]\nrobot.getDir(); // return "West"\n\n
\n\n

 

\n

Constraints:

\n\n\n", "translatedTitle": null, "translatedContent": null, "isPaidOnly": false, "difficulty": "Medium", "likes": 103, "dislikes": 235, "isLiked": null, "similarQuestions": "[{\"title\": \"Walking Robot Simulation\", \"titleSlug\": \"walking-robot-simulation\", \"difficulty\": \"Medium\", \"translatedTitle\": null}]", "exampleTestcases": "[\"Robot\",\"step\",\"step\",\"getPos\",\"getDir\",\"step\",\"step\",\"step\",\"getPos\",\"getDir\"]\n[[6,3],[2],[2],[],[],[2],[1],[4],[],[]]", "categoryTitle": "Algorithms", "contributors": [], "topicTags": [ { "name": "Design", "slug": "design", "translatedName": null, "__typename": "TopicTagNode" }, { "name": "Simulation", "slug": "simulation", "translatedName": null, "__typename": "TopicTagNode" } ], "companyTagStats": null, "codeSnippets": [ { "lang": "C++", "langSlug": "cpp", "code": "class Robot {\npublic:\n Robot(int width, int height) {\n \n }\n \n void step(int num) {\n \n }\n \n vector getPos() {\n \n }\n \n string getDir() {\n \n }\n};\n\n/**\n * Your Robot object will be instantiated and called as such:\n * Robot* obj = new Robot(width, height);\n * obj->step(num);\n * vector param_2 = obj->getPos();\n * string param_3 = obj->getDir();\n */", "__typename": "CodeSnippetNode" }, { "lang": "Java", "langSlug": "java", "code": "class Robot {\n\n public Robot(int width, int height) {\n \n }\n \n public void step(int num) {\n \n }\n \n public int[] getPos() {\n \n }\n \n public String getDir() {\n \n }\n}\n\n/**\n * Your Robot object will be instantiated and called as such:\n * Robot obj = new Robot(width, height);\n * obj.step(num);\n * int[] param_2 = obj.getPos();\n * String param_3 = obj.getDir();\n */", "__typename": "CodeSnippetNode" }, { "lang": "Python", "langSlug": "python", "code": "class Robot(object):\n\n def __init__(self, width, height):\n \"\"\"\n :type width: int\n :type height: int\n \"\"\"\n \n\n def step(self, num):\n \"\"\"\n :type num: int\n :rtype: None\n \"\"\"\n \n\n def getPos(self):\n \"\"\"\n :rtype: List[int]\n \"\"\"\n \n\n def getDir(self):\n \"\"\"\n :rtype: str\n \"\"\"\n \n\n\n# Your Robot object will be instantiated and called as such:\n# obj = Robot(width, height)\n# obj.step(num)\n# param_2 = obj.getPos()\n# param_3 = obj.getDir()", "__typename": "CodeSnippetNode" }, { "lang": "Python3", "langSlug": "python3", "code": "class Robot:\n\n def __init__(self, width: int, height: int):\n \n\n def step(self, num: int) -> None:\n \n\n def getPos(self) -> List[int]:\n \n\n def getDir(self) -> str:\n \n\n\n# Your Robot object will be instantiated and called as such:\n# obj = Robot(width, height)\n# obj.step(num)\n# param_2 = obj.getPos()\n# param_3 = obj.getDir()", "__typename": "CodeSnippetNode" }, { "lang": "C", "langSlug": "c", "code": "\n\n\ntypedef struct {\n \n} Robot;\n\n\nRobot* robotCreate(int width, int height) {\n \n}\n\nvoid robotStep(Robot* obj, int num) {\n \n}\n\nint* robotGetPos(Robot* obj, int* retSize) {\n \n}\n\nchar * robotGetDir(Robot* obj) {\n \n}\n\nvoid robotFree(Robot* obj) {\n \n}\n\n/**\n * Your Robot struct will be instantiated and called as such:\n * Robot* obj = robotCreate(width, height);\n * robotStep(obj, num);\n \n * int* param_2 = robotGetPos(obj, retSize);\n \n * char * param_3 = robotGetDir(obj);\n \n * robotFree(obj);\n*/", "__typename": "CodeSnippetNode" }, { "lang": "C#", "langSlug": "csharp", "code": "public class Robot {\n\n public Robot(int width, int height) {\n \n }\n \n public void Step(int num) {\n \n }\n \n public int[] GetPos() {\n \n }\n \n public string GetDir() {\n \n }\n}\n\n/**\n * Your Robot object will be instantiated and called as such:\n * Robot obj = new Robot(width, height);\n * obj.Step(num);\n * int[] param_2 = obj.GetPos();\n * string param_3 = obj.GetDir();\n */", "__typename": "CodeSnippetNode" }, { "lang": "JavaScript", "langSlug": "javascript", "code": "/**\n * @param {number} width\n * @param {number} height\n */\nvar Robot = function(width, height) {\n \n};\n\n/** \n * @param {number} num\n * @return {void}\n */\nRobot.prototype.step = function(num) {\n \n};\n\n/**\n * @return {number[]}\n */\nRobot.prototype.getPos = function() {\n \n};\n\n/**\n * @return {string}\n */\nRobot.prototype.getDir = function() {\n \n};\n\n/** \n * Your Robot object will be instantiated and called as such:\n * var obj = new Robot(width, height)\n * obj.step(num)\n * var param_2 = obj.getPos()\n * var param_3 = obj.getDir()\n */", "__typename": "CodeSnippetNode" }, { "lang": "Ruby", "langSlug": "ruby", "code": "class Robot\n\n=begin\n :type width: Integer\n :type height: Integer\n=end\n def initialize(width, height)\n \n end\n\n\n=begin\n :type num: Integer\n :rtype: Void\n=end\n def step(num)\n \n end\n\n\n=begin\n :rtype: Integer[]\n=end\n def get_pos()\n \n end\n\n\n=begin\n :rtype: String\n=end\n def get_dir()\n \n end\n\n\nend\n\n# Your Robot object will be instantiated and called as such:\n# obj = Robot.new(width, height)\n# obj.step(num)\n# param_2 = obj.get_pos()\n# param_3 = obj.get_dir()", "__typename": "CodeSnippetNode" }, { "lang": "Swift", "langSlug": "swift", "code": "\nclass Robot {\n\n init(_ width: Int, _ height: Int) {\n \n }\n \n func step(_ num: Int) {\n \n }\n \n func getPos() -> [Int] {\n \n }\n \n func getDir() -> String {\n \n }\n}\n\n/**\n * Your Robot object will be instantiated and called as such:\n * let obj = Robot(width, height)\n * obj.step(num)\n * let ret_2: [Int] = obj.getPos()\n * let ret_3: String = obj.getDir()\n */", "__typename": "CodeSnippetNode" }, { "lang": "Go", "langSlug": "golang", "code": "type Robot struct {\n \n}\n\n\nfunc Constructor(width int, height int) Robot {\n \n}\n\n\nfunc (this *Robot) Step(num int) {\n \n}\n\n\nfunc (this *Robot) GetPos() []int {\n \n}\n\n\nfunc (this *Robot) GetDir() string {\n \n}\n\n\n/**\n * Your Robot object will be instantiated and called as such:\n * obj := Constructor(width, height);\n * obj.Step(num);\n * param_2 := obj.GetPos();\n * param_3 := obj.GetDir();\n */", "__typename": "CodeSnippetNode" }, { "lang": "Scala", "langSlug": "scala", "code": "class Robot(_width: Int, _height: Int) {\n\n def step(num: Int) {\n \n }\n\n def getPos(): Array[Int] = {\n \n }\n\n def getDir(): String = {\n \n }\n\n}\n\n/**\n * Your Robot object will be instantiated and called as such:\n * var obj = new Robot(width, height)\n * obj.step(num)\n * var param_2 = obj.getPos()\n * var param_3 = obj.getDir()\n */", "__typename": "CodeSnippetNode" }, { "lang": "Kotlin", "langSlug": "kotlin", "code": "class Robot(width: Int, height: Int) {\n\n fun step(num: Int) {\n \n }\n\n fun getPos(): IntArray {\n \n }\n\n fun getDir(): String {\n \n }\n\n}\n\n/**\n * Your Robot object will be instantiated and called as such:\n * var obj = Robot(width, height)\n * obj.step(num)\n * var param_2 = obj.getPos()\n * var param_3 = obj.getDir()\n */", "__typename": "CodeSnippetNode" }, { "lang": "Rust", "langSlug": "rust", "code": "struct Robot {\n\n}\n\n\n/** \n * `&self` means the method takes an immutable reference.\n * If you need a mutable reference, change it to `&mut self` instead.\n */\nimpl Robot {\n\n fn new(width: i32, height: i32) -> Self {\n \n }\n \n fn step(&self, num: i32) {\n \n }\n \n fn get_pos(&self) -> Vec {\n \n }\n \n fn get_dir(&self) -> String {\n \n }\n}\n\n/**\n * Your Robot object will be instantiated and called as such:\n * let obj = Robot::new(width, height);\n * obj.step(num);\n * let ret_2: Vec = obj.get_pos();\n * let ret_3: String = obj.get_dir();\n */", "__typename": "CodeSnippetNode" }, { "lang": "PHP", "langSlug": "php", "code": "class Robot {\n /**\n * @param Integer $width\n * @param Integer $height\n */\n function __construct($width, $height) {\n \n }\n \n /**\n * @param Integer $num\n * @return NULL\n */\n function step($num) {\n \n }\n \n /**\n * @return Integer[]\n */\n function getPos() {\n \n }\n \n /**\n * @return String\n */\n function getDir() {\n \n }\n}\n\n/**\n * Your Robot object will be instantiated and called as such:\n * $obj = Robot($width, $height);\n * $obj->step($num);\n * $ret_2 = $obj->getPos();\n * $ret_3 = $obj->getDir();\n */", "__typename": "CodeSnippetNode" }, { "lang": "TypeScript", "langSlug": "typescript", "code": "class Robot {\n constructor(width: number, height: number) {\n\n }\n\n step(num: number): void {\n\n }\n\n getPos(): number[] {\n\n }\n\n getDir(): string {\n\n }\n}\n\n/**\n * Your Robot object will be instantiated and called as such:\n * var obj = new Robot(width, height)\n * obj.step(num)\n * var param_2 = obj.getPos()\n * var param_3 = obj.getDir()\n */", "__typename": "CodeSnippetNode" }, { "lang": "Racket", "langSlug": "racket", "code": "(define robot%\n (class object%\n (super-new)\n \n ; width : exact-integer?\n ; height : exact-integer?\n (init-field\n width\n height)\n \n ; step : exact-integer? -> void?\n (define/public (step num)\n\n )\n ; get-pos : -> (listof exact-integer?)\n (define/public (get-pos)\n\n )\n ; get-dir : -> string?\n (define/public (get-dir)\n\n )))\n\n;; Your robot% object will be instantiated and called as such:\n;; (define obj (new robot% [width width] [height height]))\n;; (send obj step num)\n;; (define param_2 (send obj get-pos))\n;; (define param_3 (send obj get-dir))", "__typename": "CodeSnippetNode" }, { "lang": "Erlang", "langSlug": "erlang", "code": "-spec robot_init_(Width :: integer(), Height :: integer()) -> any().\nrobot_init_(Width, Height) ->\n .\n\n-spec robot_step(Num :: integer()) -> any().\nrobot_step(Num) ->\n .\n\n-spec robot_get_pos() -> [integer()].\nrobot_get_pos() ->\n .\n\n-spec robot_get_dir() -> unicode:unicode_binary().\nrobot_get_dir() ->\n .\n\n\n%% Your functions will be called as such:\n%% robot_init_(Width, Height),\n%% robot_step(Num),\n%% Param_2 = robot_get_pos(),\n%% Param_3 = robot_get_dir(),\n\n%% robot_init_ will be called before every test case, in which you can do some necessary initializations.", "__typename": "CodeSnippetNode" }, { "lang": "Elixir", "langSlug": "elixir", "code": "defmodule Robot do\n @spec init_(width :: integer, height :: integer) :: any\n def init_(width, height) do\n\n end\n\n @spec step(num :: integer) :: any\n def step(num) do\n\n end\n\n @spec get_pos() :: [integer]\n def get_pos() do\n\n end\n\n @spec get_dir() :: String.t\n def get_dir() do\n\n end\nend\n\n# Your functions will be called as such:\n# Robot.init_(width, height)\n# Robot.step(num)\n# param_2 = Robot.get_pos()\n# param_3 = Robot.get_dir()\n\n# Robot.init_ will be called before every test case, in which you can do some necessary initializations.", "__typename": "CodeSnippetNode" } ], "stats": "{\"totalAccepted\": \"5.5K\", \"totalSubmission\": \"25.3K\", \"totalAcceptedRaw\": 5456, \"totalSubmissionRaw\": 25295, \"acRate\": \"21.6%\"}", "hints": [ "The robot only moves along the perimeter of the grid. Can you think if modulus can help you quickly compute which cell it stops at?", "After the robot moves one time, whenever the robot stops at some cell, it will always face a specific direction. i.e., The direction it faces is determined by the cell it stops at.", "Can you precompute what direction it faces when it stops at each cell along the perimeter, and reuse the results?" ], "solution": null, "status": null, "sampleTestCase": "[\"Robot\",\"step\",\"step\",\"getPos\",\"getDir\",\"step\",\"step\",\"step\",\"getPos\",\"getDir\"]\n[[6,3],[2],[2],[],[],[2],[1],[4],[],[]]", "metaData": "{\n \"classname\": \"Robot\",\n \"constructor\": {\n \"params\": [\n {\n \"type\": \"integer\",\n \"name\": \"width\"\n },\n {\n \"name\": \"height\",\n \"type\": \"integer\"\n }\n ]\n },\n \"methods\": [\n {\n \"params\": [\n {\n \"type\": \"integer\",\n \"name\": \"num\"\n }\n ],\n \"name\": \"step\",\n \"return\": {\n \"type\": \"void\"\n }\n },\n {\n \"params\": [],\n \"name\": \"getPos\",\n \"return\": {\n \"type\": \"integer[]\"\n }\n },\n {\n \"params\": [],\n \"name\": \"getDir\",\n \"return\": {\n \"type\": \"string\"\n }\n }\n ],\n \"return\": {\n \"type\": \"boolean\"\n },\n \"systemdesign\": true\n}", "judgerAvailable": true, "judgeType": "large", "mysqlSchemas": [], "enableRunCode": true, "enableTestMode": false, "enableDebugger": true, "envInfo": "{\"cpp\": [\"C++\", \"

Compiled with clang 11 using the latest C++ 17 standard.

\\r\\n\\r\\n

Your code is compiled with level two optimization (-O2). AddressSanitizer is also enabled to help detect out-of-bounds and use-after-free bugs.

\\r\\n\\r\\n

Most standard library headers are already included automatically for your convenience.

\"], \"java\": [\"Java\", \"

OpenJDK 17 . Java 8 features such as lambda expressions and stream API can be used.

\\r\\n\\r\\n

Most standard library headers are already included automatically for your convenience.

\\r\\n

Includes Pair class from https://docs.oracle.com/javase/8/javafx/api/javafx/util/Pair.html.

\"], \"python\": [\"Python\", \"

Python 2.7.12.

\\r\\n\\r\\n

Most libraries are already imported automatically for your convenience, such as array, bisect, collections. If you need more libraries, you can import it yourself.

\\r\\n\\r\\n

For Map/TreeMap data structure, you may use sortedcontainers library.

\\r\\n\\r\\n

Note that Python 2.7 will not be maintained past 2020. For the latest Python, please choose Python3 instead.

\"], \"c\": [\"C\", \"

Compiled with gcc 8.2 using the gnu99 standard.

\\r\\n\\r\\n

Your code is compiled with level one optimization (-O1). AddressSanitizer is also enabled to help detect out-of-bounds and use-after-free bugs.

\\r\\n\\r\\n

Most standard library headers are already included automatically for your convenience.

\\r\\n\\r\\n

For hash table operations, you may use uthash. \\\"uthash.h\\\" is included by default. Below are some examples:

\\r\\n\\r\\n

1. Adding an item to a hash.\\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
\\r\\n

\\r\\n\\r\\n

2. Looking up an item in a hash:\\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
\\r\\n

\\r\\n\\r\\n

3. Deleting an item in a hash:\\r\\n

\\r\\nvoid delete_user(struct hash_entry *user) {\\r\\n    HASH_DEL(users, user);  \\r\\n}\\r\\n
\\r\\n

\"], \"csharp\": [\"C#\", \"

C# 10 with .NET 6 runtime

\\r\\n\\r\\n

Your code is compiled with debug flag enabled (/debug).

\"], \"javascript\": [\"JavaScript\", \"

Node.js 16.13.2.

\\r\\n\\r\\n

Your code is run with --harmony flag, enabling new ES6 features.

\\r\\n\\r\\n

lodash.js library is included by default.

\\r\\n\\r\\n

For Priority Queue / Queue data structures, you may use datastructures-js/priority-queue and datastructures-js/queue.

\"], \"ruby\": [\"Ruby\", \"

Ruby 3.1

\\r\\n\\r\\n

Some common data structure implementations are provided in the Algorithms module: https://www.rubydoc.info/github/kanwei/algorithms/Algorithms

\"], \"swift\": [\"Swift\", \"

Swift 5.5.2.

\"], \"golang\": [\"Go\", \"

Go 1.17.6.

\\r\\n\\r\\n

Support https://godoc.org/github.com/emirpasic/gods library.

\"], \"python3\": [\"Python3\", \"

Python 3.10.

\\r\\n\\r\\n

Most libraries are already imported automatically for your convenience, such as array, bisect, collections. If you need more libraries, you can import it yourself.

\\r\\n\\r\\n

For Map/TreeMap data structure, you may use sortedcontainers library.

\"], \"scala\": [\"Scala\", \"

Scala 2.13.7.

\"], \"kotlin\": [\"Kotlin\", \"

Kotlin 1.3.10.

\"], \"rust\": [\"Rust\", \"

Rust 1.58.1

\\r\\n\\r\\n

Supports rand v0.6\\u00a0from crates.io

\"], \"php\": [\"PHP\", \"

PHP 8.1.

\\r\\n

With bcmath module

\"], \"typescript\": [\"Typescript\", \"

TypeScript 4.5.4, Node.js 16.13.2.

\\r\\n\\r\\n

Your code is run with --harmony flag, enabling new ES2020 features.

\\r\\n\\r\\n

lodash.js library is included by default.

\"], \"racket\": [\"Racket\", \"

Run with Racket 8.3.

\"], \"erlang\": [\"Erlang\", \"Erlang/OTP 24.2\"], \"elixir\": [\"Elixir\", \"Elixir 1.13.0 with Erlang/OTP 24.2\"]}", "libraryUrl": null, "adminUrl": null, "challengeQuestion": null, "__typename": "QuestionNode" } } }