Watch 10 video solutions for Robot Bounded In Circle, a medium level problem involving Math, String, Simulation. This walkthrough by NeetCode has 44,021 views views. Want to try solving it yourself? Practice on FleetCode or read the detailed text solution.
On an infinite plane, a robot initially stands at (0, 0) and faces north. Note that:
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 <= 100instructions[i] is 'G', 'L' or, 'R'.