fib2.cpp

来自「一个菲波拉契数列的DEMO程序」· C++ 代码 · 共 25 行

#include <iostream>
#include <ctime>
using namespace std;

const long num = 4000000000000;

long fib(long n) {
	if (n<=1) return 1;
	long f1 = 1,f2 = 1,f3 = 2;
	for (int i =2; i < n; i ++){
		f1 = f2;
		f2 = f3;
		f3 = f1 + f2;
	}
	return f3;
}

void main(){
	double x = clock() / CLOCKS_PER_SEC;
	fib(num);
	x = clock() / CLOCKS_PER_SEC - x;
	cout<<"Timing fib(" <<num <<"),time:" <<x <<"s\n";
	//return 0;
}