题解 | 绕距

import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        // 注意 hasNext 和 hasNextLine 的区别
        Map<String, Integer> map1 = new HashMap<>();
        for (int i = 1; in.hasNextInt(); i++) {
            int a = in.nextInt();
            map1.put("x" + i, a);
            int b = in.nextInt();
            map1.put("y" + i, b);
        }
        int x1 = map1.get("x1");
        int y1 = map1.get("y1");
        int x2 = map1.get("x2");
        int y2 = map1.get("y2");
        double o = Math.sqrt(Math.pow(x2 - x1, 2) + Math.pow(y2 - y1, 2));
        int m = Math.abs(x2 - x1) + Math.abs(y2 - y1);
        double distance = m - o;
        System.out.println(distance);
    }
}