沙漏图形 tri2str [1*+]

题目描述：
输入n，输出正倒n层星号三角形。首行顶格，星号间有一空格，效果见样例

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输入样例：
3

输出样例：

* * *
 * * 
  *
 * * 
* * *

数据规模 1<= n <=50

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train of thought：

code:

#include <bits/stdc++.h>
int main()
{
    int n;
    scanf("%d", &n);
    for (int i = 1; i <= n; i++)
    {
        for (int j = 1; j <= (i - 1); j++)
        {
            printf(" ");
        }
        for (int k = 1; k <= n - i + 1; k++)
        {
            printf("* ");
        }
        printf("\n");
    }
    for (int i = 2; i <= n; i++)
    {
        for (int j = 1; j <= (n - i); j++)
        {
            printf(" ");
        }
        for (int k = 1; k <= i; k++)
        {
            printf("* ");
        }
        printf("\n");
    }
    return 0;
}