Update spaces:
If i < n, decrease spaces by 2.
Else, increase spaces by 2.
Code
#include <bits/stdc++.h>
using namespace std;

class Solution {
public:
    // Function to print Pattern 20
    void pattern20(int n) {
        // Initialize spaces between star blocks
        int spaces = 2 * n - 2;

        // Loop for rows
        for (int i = 1; i <= 2 * n - 1; i++) {
            // Calculate stars for first half
            int stars = i;

            // Adjust stars for second half
            if (i > n) stars = 2 * n - i;

            // Print left stars
            for (int j = 1; j <= stars; j++) {
                cout << "*";
            }

            // Print spaces
            for (int j = 1; j <= spaces; j++) {
                cout << " ";
            }

            // Print right stars
            for (int j = 1; j <= stars; j++) {
                cout << "*";
            }

            // Move to next line
            cout << endl;

            // Adjust spaces fo