Package g1001_1100.s1041_robot_bounded_in_circle

Class Solution

java.lang.Object
g1001_1100.s1041_robot_bounded_in_circle.Solution
public class Solution extends java.lang.Object
1041 - Robot Bounded In Circle.

Medium

On an infinite plane, a robot initially stands at (0, 0) and faces north. Note that:

  • The north direction is the positive direction of the y-axis.
  • The south direction is the negative direction of the y-axis.
  • The east direction is the positive direction of the x-axis.
  • The west direction is the negative direction of the x-axis.

The robot can receive one of three instructions:

  • "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.

Example 1:

Input: instructions = “GGLLGG”

Output: true

Explanation: The robot is initially at (0, 0) facing the north direction.

“G”: move one step. Position: (0, 1). Direction: North.

“G”: move one step. Position: (0, 2). Direction: North.

“L”: turn 90 degrees anti-clockwise. Position: (0, 2). Direction: West.

“L”: turn 90 degrees anti-clockwise. Position: (0, 2). Direction: South.

“G”: move one step. Position: (0, 1). Direction: South.

“G”: move one step. Position: (0, 0). Direction: South.

Repeating the instructions, the robot goes into the cycle: (0, 0) –> (0, 1) –> (0, 2) –> (0, 1) –> (0, 0).

Based on that, we return true.

Example 2:

Input: instructions = “GG”

Output: false

Explanation: The robot is initially at (0, 0) facing the north direction.

“G”: move one step. Position: (0, 1). Direction: North.

“G”: move one step. Position: (0, 2). Direction: North.

Repeating the instructions, keeps advancing in the north direction and does not go into cycles.

Based on that, we return false.

Example 3:

Input: instructions = “GL”

Output: true

Explanation: The robot is initially at (0, 0) facing the north direction.

“G”: move one step. Position: (0, 1). Direction: North.

“L”: turn 90 degrees anti-clockwise. Position: (0, 1). Direction: West.

“G”: move one step. Position: (-1, 1). Direction: West.

“L”: turn 90 degrees anti-clockwise. Position: (-1, 1). Direction: South.

“G”: move one step. Position: (-1, 0). Direction: South.

“L”: turn 90 degrees anti-clockwise. Position: (-1, 0). Direction: East.

“G”: move one step. Position: (0, 0). Direction: East.

“L”: turn 90 degrees anti-clockwise. Position: (0, 0). Direction: North.

Repeating the instructions, the robot goes into the cycle: (0, 0) –> (0, 1) –> (-1, 1) –> (-1, 0) –> (0, 0).

Based on that, we return true.

Constraints:

  • 1 <= instructions.length <= 100
  • instructions[i] is 'G', 'L' or, 'R'.

  • Constructor Summary

    Constructors
    Constructor
    Description
    Solution()
     

  • Method Summary

    Modifier and Type
    Method
    Description
    boolean
    isRobotBounded(java.lang.String instructions)
     

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Constructor Details

    • Solution

      public Solution()

  • Method Details

    • isRobotBounded

      public boolean isRobotBounded(java.lang.String instructions)