# C++斐波納契數列

C++中的斐波納契係數實現：在斐波納契系列的情況下，下一個數位是前兩個數位的總和，例如：`0`,`1`,`1`,`2`,`3`,`5`,`8`,`13`,`21`等。斐波那契數列的前兩個數位是：`0``1`

• 不使用遞迴實現斐波那契數列
• 使用遞迴實現斐波那契數列

## 不使用遞迴實現斐波那契數列

``````#include <iostream>
using namespace std;
int main() {
int n1=0,n2=1,n3,i,number;
cout<<"Enter the number of elements: ";
cin>>number;
cout<<n1<<" "<<n2<<" "; //printing 0 and 1
//loop starts from 2 because 0 and 1 are already printed
for(i=2;i<number;++i)
{
n3=n1+n2;
cout<<n3<<" ";
n1=n2;
n2=n3;
}
return 0;
}
``````

``````Enter the number of elements: 10
0 1 1 2 3 5 8 13 21 34
``````

## 在C++中使用遞迴實現斐波那契數列

``````#include<iostream>
using namespace std;
void printFibonacci(int n){
static int n1=0, n2=1, n3;
if(n>0){
n3 = n1 + n2;
n1 = n2;
n2 = n3;
cout<<n3<<" ";
printFibonacci(n-1);
}
}
int main(){
int n;
cout<<"Enter the number of elements: ";
cin>>n;
cout<<"Fibonacci Series: ";
cout<<"0 "<<"1 ";
printFibonacci(n-2);  //n-2 because 2 numbers are already printed
return 0;
}
``````

``````Enter the number of elements: 15
Fibonacci Series: 0 1 1 2 3 5 8 13 21 34 55 89 144 233 377
``````