输入n，用最快的方法求斐波那契数列的第n项

/************************************************************************
*
*  输入n，用最快的方法求斐波那契数列的第n项 
*
/************************************************************************/

#include "stdio.h"

int fabonacci(int n)
{
    int first = 0, second = 1;
    int tmp = 0;
    if (n == 1)
    {
        return 0;
    }
    if (n == 2)
    {
        return 1;
    }
    while(n-- > 2)
    {
        tmp = first + second;
        first = second;
        second = tmp;
    }
    return second;
}

void main()
{
    for (int i = 1; i <= 20; i++)
    {
        printf("fabonacci(%d) = %d\n", i, fabonacci(i));
    }
}