题解 | #X形图案#

#include <iostream>
using namespace std;

int main() {
    int n;
    while (cin >> n)
    {
        if (n % 2 == 1)
        {
            int k = n / 2;
            for (int i = 0; i <= k; ++i)
            {
                int j;
                for (j = 0; j < i; ++j)
                {
                    cout << " ";
                }
                cout << "*";
                for (j = 0; j < (n - 2 - 2 * i); ++j)
                {
                    cout << " ";
                }
                if (i != k)
                    cout << "*" << endl;
                else
                    cout << endl;
            }
            for (int i = 0; i < k; ++i)
            {
                int j;
                for (j = 0; j < k - i - 1 ; ++j)
                {
                    cout << " ";
                }
                cout << "*";
                for (j = 0; j <= 2 * i; ++j)
                {
                    cout << " ";
                }
                cout << "*" << endl;
            }
        }
        else 
        {
            int k = n / 2;
            for (int i = 0; i < k; ++i)
            {
                int j;
                for (j = 0; j < i; ++j)
                {
                    cout << " ";
                }
                cout << "*";
                for (j = 0; j < (n - 2 - 2 * i); ++j)
                {
                    cout << " ";
                }
                cout << "*" << endl;

            }
            for (int i = 0; i < k; ++i)
            {
                int j;
                for (j = 0; j < k - i - 1 ; ++j)
                {
                    cout << " ";
                }
                cout << "*";
                for (j = 0; j < 2 * i; ++j)
                {
                    cout << " ";
                }
                cout << "*" << endl;
            }

        }
    }
}
// 64 位输出请用 printf("%lld")

分奇偶讨论，一次要写清楚不容易。