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  • Self Numbers

    Description

    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.

    Input

    No input for this problem.

    Output

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

    Sample 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
    
    
    
    
    
    
    
    
    
    
    #include <iostream>
    using namespace std;
    int a[10100];
    
    int p(int n)
    {
        int t;
    	t=n;
        while(n!=0)
        {
            t+=n%10;
            n=n/10;
        }
        return t;
    }
    
    int main()
    {int i,j;
    
    
    memset(a,0,sizeof(a));
    
    for(i=1;i<10000;i++)
    {j=p(i);
    a[j]=1;}
    for(i=1;i<10000;i++)
    if(a[i]!=1)
    cout<<i<<endl;
    
    return 0;}
    筛选法








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  • 原文地址:https://www.cnblogs.com/lengxia/p/4387843.html
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