Java道格拉斯普克抽稀算法

以下是Java实现的道格拉斯-普克抽稀算法的示例代码：

import java.util.ArrayList;
import java.util.List;

public class DouglasPeucker {

    public static List<Point> douglasPeucker(List<Point> points, double epsilon) {
        if (points == null || points.size() < 3) {
            return points;
        }

        int maxIndex = 0;
        double maxDistance = 0;

        int endIndex = points.size() - 1;

        for (int i = 1; i < endIndex; i++) {
            double distance = perpendicularDistance(points.get(i), points.get(0), points.get(endIndex));
            if (distance > maxDistance) {
                maxIndex = i;
                maxDistance = distance;
            }
        }

        List<Point> resultList = new ArrayList<>();

        if (maxDistance > epsilon) {
            List<Point> leftList = points.subList(0, maxIndex + 1);
            List<Point> rightList = points.subList(maxIndex, endIndex + 1);

            List<Point> leftResultList = douglasPeucker(leftList, epsilon);
            List<Point> rightResultList = douglasPeucker(rightList, epsilon);

            resultList.addAll(leftResultList.subList(0, leftResultList.size() - 1));
            resultList.addAll(rightResultList);
        } else {
            resultList.add(points.get(0));
            resultList.add(points.get(endIndex));
        }

        return resultList;
    }

    private static double perpendicularDistance(Point point, Point start, Point end) {
        double area = Math.abs(0.5 * (start.getX() * end.getY() + end.getX() * point.getY() + point.getX() * start.getY() - end.getX() * start.getY() - point.getX() * end.getY() - start.getX() * point.getY()));
        double bottom = Math.sqrt(Math.pow(start.getX() - end.getX(),2) + Math.pow(start.getY() - end.getY(), 2));
        double height = area / bottom * 2;
        return height;
    }

    public static class Point {
        private double x;
        private double y;

        public Point(double x, double y) {
            this.x = x;
            this.y = y;
        }

        public double getX() {
            return x;
        }

        public double getY() {
            return y;
        }
    }
}

上述代码中，`douglasPeucker`方法接收一个点集和一个误差值`epsilon`，返回一个抽稀后的点集。`perpendicularDistance`方法用于计算一个点到一条线段的垂直距离。`Point`类表示一个二维坐标点。