题解 | #箭形图案#

#include<iostream>
#include<cmath>
using namespace std;
int main()
{
    int k;
    while (cin >> k)
    {
        
        for (int i = 0; i < 2*k+1; i++)
        {
            for (int j = 0; j < 2 * k + 1; j++)
            {
                if (j < abs(2 * k - 2 * i)) cout << " ";
            }
            cout << string(k+1 - abs(k - i), '*') << endl;          
        }
   }
    return 0;
}