In 1949 the Indian mathematician D.R. Kaprekar discovered a class

of numbers called self-numbers. For any positive integer n, define

d(n) to be n plus the sum of the digits of n. (The d stands

for digitadition, a term coined by Kaprekar.) For example, d(75) = 75 + 7 + 5 = 87. Given any positive integer n as a starting

point, you can construct the infinite increasing sequence of integers

n, d(n), d(d(n)), d(d(d(n))), .... For example, if you start with

33, the next number is 33 + 3 + 3 = 39, the next is 39 + 3 + 9 = 51, the next

is 51 + 5 + 1 = 57, and so you generate the sequence

33, 39, 51, 57, 69, 84, 96, 111, 114, 120, 123, 129, 141, ...

The number n is called a generator of d(n). In the

sequence above, 33 is a generator of 39, 39 is a generator of 51, 51

is a generator of 57, and so on. Some numbers have more than one

generator: for example, 101 has two generators, 91 and 100. A number

with no generators is a self-number. There are thirteen

self-numbers less than 100: 1, 3, 5, 7, 9, 20, 31, 42, 53, 64, 75, 86,

and 97.

Write a program to output all positive self-numbers less than 10000

in increasing order, one per line.

Output
1
3
5
7
9
20
31
42
53
64
 |
 |       <-- a lot more numbers
 |
9903
9914
9925
9927
9938
9949
9960
9971
9982
9993

Solution

#include?<iostream>
using?namespace?std;

const?long?N?=?10000;?????//最大自然數
char?Arr[N?+?9*4]={0};???//是否是被排除的數字？?+9*4是為了要再多放4位數

long?DealNum(long?n)
{
??long?sum?=?n;
??while?(n?!=?0)
??{
????sum?+=?n%10;
????n?/=?10;
??}
??return?sum;
}

int?main()
{
??int?i;
??for(i?=?1;?i?<?N;?i++)
??{
????Arr[DealNum(i)]?=?1;
??}
??for(i?=?1;?i?<?N;?i++)
??{
????if?(!Arr[i])
????????cout<<i<<endl;
??}
??return?0;
}