斐波拉契数列

# include <stdio.h>

int main(void)
{
    int n;
    int f1,f2,f3;
    int i;
    f1 = 1;
    f2 = 2;

    printf("请输入要求的第位置:\n");
    scanf("%d",&n);

    if(n == 1)
        f3 = 1;
    else if (n == 2)
        f3 = 2;
    else
        for(i = 3; i <= n; ++i)
        {f3 = f1 + f2;
            f1 = f2;
            f2 = f3;
        }
    printf("%d\n",f3);
    
    return 0;


}