# 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

```