Help me in solving LCPPAS166 problem

help
,
1

My issue

armstrong number using function

My code

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

int countDigits(int n) {
    // Complete the fuction.
}

// Function to check if a number is Armstrong: print YES or NO
void isArmstrongNumber(int num) {
    // Complete the fuction
}

int main() {
    int n;
    cin >> n;

    isArmstrongNumber(n);
    return 0;
}

Learning course: ATT - C++
Problem Link: Armstrong Number in ATT - C++