int main()
{
int i, j, n;
printf("input the number of line: ");
scanf("%d", &n);
printf("\n");
for (i = 0; i <= n; i++)
for (j = 1; j < (n - i) * 2 + 1; j++)
printf(" ");
for (j = 1; j <= 4 * i + 1; j++)
printf("*");
}
} 這個就是三角形