C++解答

# include <iostream>
using namespace std;
char a[30] = "0123456789ABCDEFGHIJKLMN";
int main(){
    int n;
    cin >> n;
    for (int i = 1; i <= n; i ++){
        for (int j = 1; j <= n - i; j ++){
            cout << " ";
        }
        for (int j = 1; j <= i; j ++){
            cout << a[j];
        }
        for (int j = i - 1; j >= 1; j --){
            cout << a[j];
        }
        cout << endl;
    }
    return 0;
}