{ "data": { "question": { "questionId": "1119", "questionFrontendId": "1041", "categoryTitle": "Algorithms", "boundTopicId": 4573, "title": "Robot Bounded In Circle", "titleSlug": "robot-bounded-in-circle", "content": "
On an infinite plane, a robot initially stands at (0, 0)
and faces north. Note that:
The robot can receive one of three instructions:
\n\n"G"
: go straight 1 unit."L"
: turn 90 degrees to the left (i.e., anti-clockwise direction)."R"
: turn 90 degrees to the right (i.e., clockwise direction).The robot performs the instructions
given in order, and repeats them forever.
Return true
if and only if there exists a circle in the plane such that the robot never leaves the circle.
\n
Example 1:
\n\n\nInput: instructions = "GGLLGG"\nOutput: true\nExplanation: The robot is initially at (0, 0) facing the north direction.\n"G": move one step. Position: (0, 1). Direction: North.\n"G": move one step. Position: (0, 2). Direction: North.\n"L": turn 90 degrees anti-clockwise. Position: (0, 2). Direction: West.\n"L": turn 90 degrees anti-clockwise. Position: (0, 2). Direction: South.\n"G": move one step. Position: (0, 1). Direction: South.\n"G": move one step. Position: (0, 0). Direction: South.\nRepeating the instructions, the robot goes into the cycle: (0, 0) --> (0, 1) --> (0, 2) --> (0, 1) --> (0, 0).\nBased on that, we return true.\n\n\n
Example 2:
\n\n\nInput: instructions = "GG"\nOutput: false\nExplanation: The robot is initially at (0, 0) facing the north direction.\n"G": move one step. Position: (0, 1). Direction: North.\n"G": move one step. Position: (0, 2). Direction: North.\nRepeating the instructions, keeps advancing in the north direction and does not go into cycles.\nBased on that, we return false.\n\n\n
Example 3:
\n\n\nInput: instructions = "GL"\nOutput: true\nExplanation: The robot is initially at (0, 0) facing the north direction.\n"G": move one step. Position: (0, 1). Direction: North.\n"L": turn 90 degrees anti-clockwise. Position: (0, 1). Direction: West.\n"G": move one step. Position: (-1, 1). Direction: West.\n"L": turn 90 degrees anti-clockwise. Position: (-1, 1). Direction: South.\n"G": move one step. Position: (-1, 0). Direction: South.\n"L": turn 90 degrees anti-clockwise. Position: (-1, 0). Direction: East.\n"G": move one step. Position: (0, 0). Direction: East.\n"L": turn 90 degrees anti-clockwise. Position: (0, 0). Direction: North.\nRepeating the instructions, the robot goes into the cycle: (0, 0) --> (0, 1) --> (-1, 1) --> (-1, 0) --> (0, 0).\nBased on that, we return true.\n\n\n
\n
Constraints:
\n\n1 <= instructions.length <= 100
instructions[i]
is 'G'
, 'L'
or, 'R'
.在无限的平面上,机器人最初位于 (0, 0)
处,面朝北方。注意:
机器人可以接受下列三条指令之一:
\n\n\"G\"
:直走 1 个单位\"L\"
:左转 90 度\"R\"
:右转 90 度机器人按顺序执行指令 instructions
,并一直重复它们。
只有在平面中存在环使得机器人永远无法离开时,返回 true
。否则,返回 false
。
\n\n
示例 1:
\n\n\n输入:instructions = \"GGLLGG\"\n输出:true\n解释:机器人最初在(0,0)处,面向北方。\n“G”:移动一步。位置:(0,1)方向:北。\n“G”:移动一步。位置:(0,2).方向:北。\n“L”:逆时针旋转90度。位置:(0,2).方向:西。\n“L”:逆时针旋转90度。位置:(0,2)方向:南。\n“G”:移动一步。位置:(0,1)方向:南。\n“G”:移动一步。位置:(0,0)方向:南。\n重复指令,机器人进入循环:(0,0)——>(0,1)——>(0,2)——>(0,1)——>(0,0)。\n在此基础上,我们返回true。\n\n\n
示例 2:
\n\n\n输入:instructions = \"GG\"\n输出:false\n解释:机器人最初在(0,0)处,面向北方。\n“G”:移动一步。位置:(0,1)方向:北。\n“G”:移动一步。位置:(0,2).方向:北。\n重复这些指示,继续朝北前进,不会进入循环。\n在此基础上,返回false。\n\n\n
示例 3:
\n\n\n输入:instructions = \"GL\"\n输出:true\n解释:机器人最初在(0,0)处,面向北方。\n“G”:移动一步。位置:(0,1)方向:北。\n“L”:逆时针旋转90度。位置:(0,1).方向:西。\n“G”:移动一步。位置:(- 1,1)方向:西。\n“L”:逆时针旋转90度。位置:(- 1,1)方向:南。\n“G”:移动一步。位置:(- 1,0)方向:南。\n“L”:逆时针旋转90度。位置:(- 1,0)方向:东方。\n“G”:移动一步。位置:(0,0)方向:东方。\n“L”:逆时针旋转90度。位置:(0,0)方向:北。\n重复指令,机器人进入循环:(0,0)——>(0,1)——>(- 1,1)——>(- 1,0)——>(0,0)。\n在此基础上,我们返回true。\n\n
\n\n
提示:
\n\n1 <= instructions.length <= 100
instructions[i]
仅包含 'G', 'L', 'R'
\\u7248\\u672c\\uff1a \\u7f16\\u8bd1\\u65f6\\uff0c\\u5c06\\u4f1a\\u91c7\\u7528 \\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\\uff1a \\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 \\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>, 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\\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@5.3.0<\\/a> \\u548c datastructures-js\\/queue@4.2.1<\\/a>\\u3002<\\/p>\"],\"racket\":[\"Racket\",\"clang 11<\\/code> \\u91c7\\u7528\\u6700\\u65b0C++ 20\\u6807\\u51c6\\u3002<\\/p>\\r\\n\\r\\n
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out-of-bounds<\\/code>\\u548c
use-after-free<\\/code>\\u9519\\u8bef\\u3002<\\/p>\\r\\n\\r\\n
OpenJDK 17<\\/code>\\u3002\\u53ef\\u4ee5\\u4f7f\\u7528Java 8\\u7684\\u7279\\u6027\\u4f8b\\u5982\\uff0clambda expressions \\u548c stream API\\u3002<\\/p>\\r\\n\\r\\n
Python 2.7.12<\\/code><\\/p>\\r\\n\\r\\n
GCC 8.2<\\/code>\\uff0c\\u91c7\\u7528GNU11\\u6807\\u51c6\\u3002<\\/p>\\r\\n\\r\\n
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use-after-free<\\/code>\\u9519\\u8bef\\u3002<\\/p>\\r\\n\\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
\\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
\\r\\nvoid delete_user(struct hash_entry *user) {\\r\\n HASH_DEL(users, user); \\r\\n}\\r\\n<\\/pre>\\r\\n<\\/p>\"],\"csharp\":[\"C#\",\"
Node.js 16.13.2<\\/code><\\/p>\\r\\n\\r\\n
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Ruby 3.1<\\/code>\\u6267\\u884c<\\/p>\\r\\n\\r\\n
Swift 5.5.2<\\/code><\\/p>\\r\\n\\r\\n
Go 1.21<\\/code><\\/p>\\r\\n\\r\\n
Python 3.10<\\/code><\\/p>\\r\\n\\r\\n
Scala 2.13<\\/code><\\/p>\"],\"kotlin\":[\"Kotlin\",\"
Kotlin 1.9.0<\\/code><\\/p>\\r\\n\\r\\n
rust 1.58.1<\\/code><\\/p>\\r\\n\\r\\n
PHP 8.1<\\/code>.<\\/p>\\r\\n\\r\\n