Self-describing numbers | Rosetta Code | #14

URL to the problem page: http://rosettacode.org/wiki/Self-describing_numbers


There are several so-called "self-describing" or "self-descriptive" integers.
An integer is said to be "self-describing" if it has the property that, when digit positions are labeled 0 to N-1, the digit in each position is equal to the number of times that that digit appears in the number.

For example, 2020 is a four-digit self describing number:

• position 0 has value 2 and there are two 0s in the number; 
• position 1 has value 0 and there are no 1s in the number; 
• position 2 has value 2 and there are two 2s; 
• position 3 has value 0 and there are zero 3s. 

Display the first 5 Self-describing numbers.

#include <iostream>

using namespace std;

int power(int a, int b) {

    int result = 1;

    for (int i = 0; i < b; i++) {

        result *= a;

    }

    return result;

}

int main() {

    int cnt, cnt2, digits, tmp, selfdesnum = 0;

    cout << "First 5 Self-describing numbers are:" << endl;

    for (int i = 1; selfdesnum < 5; i++) {

        digits = 1;

        tmp = i;

        cnt2 = 0;

        while (tmp >= 10) {

            digits++;

            tmp /= 10;

        }

        int* numbers = new int[digits];

        for (int j = 0; j < digits; j++) {

            numbers[j] = (i % power(10, j + 1)) / power(10, j);

        }

        for (int j = 0; j < digits; j++) {

            cnt = 0;

            tmp = digits - j - 1;

            for (int k = 0; k < digits; k++) {

                if (numbers[k] == tmp) {

                    cnt++;

                }

            }

            if (cnt != numbers[j]) {

                cnt2++;

                break;

            }

        }

        if (cnt2 == 0) {

            selfdesnum++;

            cout << i << endl;

        }

    }

    return 0;

}

CLICK TO SEE THE OUTPUT.