Leetcode: Robot Bounded In Circle

Robot Bounded In Circle

Similar Problems:

On an infinite plane, a robot initially stands at (0, 0) and faces north. The robot can receive one of three instructions:

  • “G”: go straight 1 unit;
  • “L”: turn 90 degrees to the left;
  • “R”: turn 90 degress to the right.

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.

Example 1:

Input: "GGLLGG"
Output: true
The robot moves from (0,0) to (0,2), turns 180 degrees, and then returns to (0,0).
When repeating these instructions, the robot remains in the circle of radius 2 centered at the origin.

Example 2:

Input: "GG"
Output: false
The robot moves north indefinitely.

Example 3:

Input: "GL"
Output: true
The robot moves from (0, 0) -> (0, 1) -> (-1, 1) -> (-1, 0) -> (0, 0) -> ...


  1. 1 <= instructions.length <= 100
  2. instructions[i] is in {‘G’, ‘L’, ‘R’}

Github: code.dennyzhang.com

Credits To: leetcode.com

Leave me comments, if you have better ways to solve.

  • Solution: XXX

General Thinkings:

Key Observations:

Walk Through Testdata

// Blog link: https://code.dennyzhang.com/robot-bounded-in-circle


Share It, If You Like It.

Leave a Reply

Your email address will not be published.