README.md

1041. Robot Bounded In Circle

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 Explanation: 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 Explanation: The robot moves north indefinitely. 

Example 3:

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

Note:

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

Solutions (Rust)

1. Solution

implSolution{pubfnis_robot_bounded(instructions:String) -> bool{letmut position = (0,0);letmut direction = 0;for ins in instructions.chars(){match(ins, direction % 4){('G',0) => position.1 += 1,('G',1) => position.0 += 1,('G',2) => position.1 -= 1,('G',3) => position.0 -= 1,('L', _) => direction += 3, _ => direction += 1,}} position == (0,0) || direction % 4 != 0}}