# 用递归求第n项的值

1，2，4，2，3，6，12，6，3，....求第n项值

## template

```cpp
#include <stdio.h>
int fun(int n, int *x, int *y)
{
    int sum = 0, i;
    int size = 0;
    int dd = 1;
    for (i = 1; i <= (*x); i++)
    {
        sum += (2 * i - 1);
    }
    if (sum == n)
    {
        *y = 2 * (*x) - 1;
        return (*x);
    }
    else if (sum > n)
    {
        (*y) = n - (sum - (2 * (*x) - 1));
        size = 2 * (*x) - 1;
        dd = (*x);
        for (i = 2; i <= (*y); i++)
        {
            if (i <= (*x))
                dd *= 2;
            else
                dd /= 2;
        }
        return dd;
    }
    else
    {
        (*x)++;
        return fun(n, x, y);
    }
}
int main()
{
    int n;
    int row = 1, col = 0;
    int val;
    row = 1;
    col = 0;
    printf("请输入n：");
    scanf("%d", &n);
    val = fun(n, &row, &col);
    printf("第%d项是：%d\n", n, val);
    return 0;
}
```

## 答案

```cpp

```

## 选项

### A

```cpp

```

### B

```cpp

```

### C

```cpp

```