4-11 兔子繁衍问题

//兔子繁衍问题
//斐波那契数列 
#include<stdio.h>
int main(int argc,char const *argv[])
{
	int n;
	while(1)
	{
		scanf("%d",&n);
		if(n>=1&&n<=10000)
			break;
		printf("请重新输入:");
	}
	int month=1;
	int pre=1,now=0;				//初始值 
	int sum=1;
	if(n==1)
		month=1;
	else
	{
		month++;
		now=pre;
		pre=0;
		sum=pre+now;
		while(sum<n)
		{
			month++;
			pre=now;
			now=sum;
			sum=pre+now;
		}
	}
	printf("兔子总数达到%d最少需要到第%d个月\n",n,month);
	 
	return 0;
}