题解 | 点到直线距离

import java.util.*;

public class Main {
    static class Point {
        double x,y;
        
        Point(double a, double b) {
            x = a;
            y = b;
        }
    }
    
    static class Line {
        Point pointA, pointB;
        
        Line(Point a, Point b) {
            pointA = a;
            pointB = b;
        }
    }
    
    static double getDistance(Point P, Line L) {
        double A = L.pointB.y-L.pointA.y;
        double B = L.pointA.x-L.pointB.x;
        double C = -B*L.pointA.y + L.pointA.x*(-A);
        double temp = Math.pow(A,2)+Math.pow(B,2);
        double lower = Math.pow(temp,0.5);
        temp = A*P.x+B*P.y+C;
        double upper = Math.abs(temp);
        return upper/lower;
    }
 
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int a = scanner.nextInt();
        int b = scanner.nextInt();
        int sx = scanner.nextInt();
        int sy = scanner.nextInt();
        int tx = scanner.nextInt();
        int ty = scanner.nextInt();
        
        Point pointA = new Point(sx, sy);
        Point pointB = new Point(tx, ty);
        Point pointC = new Point(a, b);
        Line line = new Line(pointA, pointB);
        
        System.out.printf("%.2f", getDistance(pointC, line));
        scanner.close();
    }
}