[Algorithm] 백준알고리즘_SelfNumber

SelfNumber

1. Question

- If you start with 33, the next number is 33 + 3 +3 = 39, the next is 39 + 3 + 9 = 51 and so you generate the sequence

33, 39, 51, 57....

- d(n) n is called a generator of d(n)

- Some numbers have more than one generator

- A number with no generators is a self-number

- Write a program to output all positive self-numbers less than 10000 in increasing order, one per line

2. Solution

package stepByStep; public class SelfNum { int calc (int number) { int sum = 0; if (number < 10000){ int a = number / 1000; int b = number / 100 % 10; int c = number / 10 % 10; int d = number % 10; sum = a + b + c + d + number; } return sum; } public static void main (String[] args) { SelfNum aa = new SelfNum(); int arr[] = new int[10000]; int number = 1; for(int i = 0; i < 10000; i++, number++) { if (aa.calc(number) < 10000) { arr[aa.calc(number)] = aa.calc(number); } } for (int k = 1; k < arr.length; k++) { if(arr[k] == 0) { System.out.println(k); } } } }