public class Test02 { public static void main(String[] args) { Count c = new Count(); System.out.println(c.sum(1)); System.out.println(c.sum(2)); 1 2 3 4 5 第3题 第4题 System.out.println(c.sum(3)); System.out.println(c.sum(4)); System.out.println(c.sum(5)); System.out.println(c.sum(6)); System.out.println(c.sum(7)); System.out.println(c.sum(8)); System.out.println(c.sum(9)); System.out.println(c.sum(10)); } } class Count{ public int sum(int n){ if(n==10){//第10天 return 1; }else{ /* * 第9天没吃之前是 第10天+1个的2倍 * 第8天没吃之前是 第9天+1个的2倍 * 。。。。 */ return (sum(n+1)+1)*2; } } }