Princeton Algorithm Part 1 Week

Point 和LineSegment没有什么好写的，作业大部分已给出。 倒是很好的练习了java的基础。

Point Class:

import java.util.Comparator;
import edu.princeton.cs.algs4.StdDraw;

public class Point implements Comparable<Point> {

    private final int x; // x-coordinate of this point
    private final int y; // y-coordinate of this point

    public Point(int x, int y) {
        /* DO NOT MODIFY */
        this.x = x;
        this.y = y;
    }

    public void draw() {
        /* DO NOT MODIFY */
        StdDraw.point(x, y);
    }

    public void drawTo(Point that) {
        /* DO NOT MODIFY */
        StdDraw.line(this.x, this.y, that.x, that.y);
    }

    public double slopeTo(Point that) {
        if (this.x == that.x) {
            if (this.y == that.y)
                return Double.NEGATIVE_INFINITY;
            return Double.POSITIVE_INFINITY;
        }

        if (this.y == that.y)
            return 0;

        return (that.y - this.y) / (that.x - this.x);
    }

    public int compareTo(Point that) {
        if (this.x == that.x && this.y == that.y)
            return 0;

        if (this.y < that.y || this.y == that.y || this.x < that.x)
            return -1; // this point is less than that point;
        return 1;
    }

    public String toString() {
        /* DO NOT MODIFY */
        return "(" + x + ", " + y + ")";
    }

    public Comparator<Point> slopeOrder() {
        return new SlopeComparator();
    }

    private class SlopeComparator implements Comparator<Point> {
        @Override
        public int compare(Point o1, Point o2) {
            double ox1 = slopeTo(o1);
            double ox2 = slopeTo(o2);
            if (ox1 < ox2)
                return -1;
            else if (ox1 > ox2)
                return 1;
            else
                return 0;
        }
    }

    public static void main(String[] args) {
        /* YOUR CODE HERE */
    }
}

Line segment data type:

public class LineSegment {
    private final Point p; // one endpoint of this line segment
    private final Point q; // the other endpoint of this line segment

    public LineSegment(Point p, Point q) {
        if (p == null || q == null) {
            throw new NullPointerException("argument is null");
        }
        this.p = p;
        this.q = q;
    }

    public void draw() {
        p.drawTo(q);
    }

    public String toString() {
        return p + " -> " + q;
    }

    public int hashCode() {
        throw new UnsupportedOperationException();
    }
}