任何精妙的解法都离不开百次千次乃至万次的思考与练习！

#include <iostream>

using namespace std;
int n;

int main(void) {
  scanf("%d", &n);
  for (int i = 0; i < n >> 1; ++i) {
    for (int j = 0; j < (n >> 1) - i; ++j) putchar(' ');
    for (int j = 0; j < (i << 1 | 1); ++j) putchar('*');
    for (int j = 0; j < (n >> 1) - i; ++j) putchar(' ');
    printf("\n");
  }
  for (int i = 0; i < n; ++i) printf("*");
  printf("\n");
  for (int i = 0; i < n >> 1; ++i) {
    for (int j = 0; j < i + 1; ++j)            putchar(' ');
    for (int j = 0; j < n - 2 - (i << 1); ++j) putchar('*');
    for (int j = 0; j < i + 1; ++j)            putchar(' ');
    printf("\n");
  }

  return 0;
}