/*
P125
清单7.15  使用迭代求第N个Fibonacci数
*/
#include <iostream>
int fib(int position);
int main(){
    using namespace std;
    int answer,position;
    cout << "Which position? ";
    cin >> position;
    cout << "\n";
    answer = fib(position);
    cout << answer << "th is the " << position << " Fibonacci number.\n";
    cin >> position;
    return 0;
}

int fib(int position){
    if(position < 3) return 1;
    int last  = 1;
    int result = 0;
    int tmp = 0;
    for(int b = 1;b<=position;b++){
        if(b < 3) last = 1;
            result = last + result;
            tmp = result;
            result = last;
            last = tmp;
    }
    //return result;
}