题解 | 变幻莫测

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
        // 注意 while 处理多个 case
        while (in.hasNext()) {
            int a = in.nextInt();
            int b = in.nextInt();
            if (a == b) {
                System.out.println(0);
                continue;
            }
            if (a == 0) {
                System.out.println(2);
                continue;
            }
            if (b == 0) {
                System.out.println(1);
                continue;
            }

            if (Math.abs(a - b) % 2 == 0) {
                int count = 0;
                while (true) {
                    int t = a + b;
                    int g = a - b;
                    a = t;
                    b = g;
                    count++;
                    if (a == 0) {
                        count += 2;
                        break;
                    }
                    if (b == 0) {
                        count += 1;
                        break;
                    }

                }
                System.out.println(count);
            } else {
                System.out.println(-1);
            }
        }
    }
}