Question

C++Fibonacci 数列

输入[0,90]范围内的整数 n，输出 Fibonacci 数列第 n 项的值 f(n):
f(0) = 0，f(1) = 1；当 n>1 时，f(n) = f(n-2) + f(n-1)

Answer 1

90项肥波数列，要用64位整数：

#include <iostream>

using namespace std;

typedef  unsigned long long int uint64;

uint64 f(int n)

{

uint64 f0=0, f1=1;

uint64 fn;

if (n<1)

return 0;

if (n==1)

return 1;

for (int i=2; i<=n; ++i)

{

fn=f1+f0;

f0=f1;

f1=fn;

}

return fn;

}

int main()

{

int n;

cin>>n;

cout<<f(n)<<endl;

return 0;

}