困于环中的机器人

/*
 * Problem: Determine if a robot stays in a circle after executing a set of instructions repeatedly.
 * Instructions:
 * - 'G': Go straight 1 unit
 * - 'L': Turn left 90 degrees
 * - 'R': Turn right 90 degrees
 * The robot initially faces north (positive y direction).
 * The robot's movement directions are represented as:
 * 0: North, 1: East, 2: South, 3: West
 * This solution uses Java Streams to process the instructions.
 */
import java.util.stream.IntStream;

public class RobotCircleStream {
    public boolean isRobotBounded(String instructions) {
        int[] position = {0, 0}; // Initial position (x, y)
        int[] direction = {0, 1}; // Initial direction (north)
        int[][] directions = {{0, 1}, {1, 0}, {0, -1}, {-1, 0}}; // N, E, S, W

        // Process instructions using streams
        IntStream.range(0, instructions.length()).forEach(i -> {
            char instruction = instructions.charAt(i);
            if (instruction == 'G') {
                position[0] += direction[0];
                position[1] += direction[1];
            } else if (instruction == 'L') {
                direction = directions[(directionIndex(direction) + 3) % 4];
            } else if (instruction == 'R') {
                direction = directions[(directionIndex(direction) + 1) % 4];
            }
        });

        // Check if the robot is back at the origin or not facing north
        return (position[0] == 0 && position[1] == 0) || directionIndex(direction) != 0;
    }

    // Helper method to determine direction index
    private int directionIndex(int[] direction) {
        if (direction[0] == 0 && direction[1] == 1) return 0; // North
        if (direction[0] == 1 && direction[1] == 0) return 1; // East
        if (direction[0] == 0 && direction[1] == -1) return 2; // South
        return 3; // West
    }
}