In order to print numbers from N to 1 and 1 to N, we can simply make recursive call for successive numbers.

We have n, in order to print from n to 1, it is evident that at any function call, we can just print the number and hand over the control to the next recursive call.
Let's print from 1 to n. Just look from the perspective of a recursive function, it prints its parameter n, then the recursive call happens. When the call returns, we can assume that numbers from n-1 to 1 and 1 to n-1 are already printed, because of that call.
Since we know until the recursive call returns, no code below the call executes, consider when we again print n(after the call), we can achieve what we need. By the time we are printing n for the 2nd time, numbers from n to 1 and 1 to n-1 are already printed.

Code

#include <bits/stdc++.h>
using namespace std;

// Solution class containing the recursive function
class Solution {
public:
    // Recursive function to print N to 1 and then 1 to N
    void printBothWays(int n) {
        // Base case: if n is 0, return
        if (n == 0) return;

        // Print the current number in descending order
        cout << n << " ";

        // Recursive call for n - 1
        printBothWays(n - 1);

        // Print the current number in ascending order
        cout << n << " ";
    }
};

// Main driver function
int main() {
    int n = 5;

    // Create object of Solution class
    Solution obj;

    // Call the function to print both ways
    obj.printBothWays(n);

    cout << endl;
    return 0;
}