October 4, 2022

#### Given a number we have to print fibonacci series of a number.

so what is fibonacci series?

In fibonacci series,next number is the sum of two previous number.

for example-0,1,1,2,3,5,8.

there are two way to print fibonacci series –

1-with recursion

2-without recursion.

Approach 1: With recursion

```#include<iostream>
using namespace std;
int fibonacci(int n)
{
if(n == 0 || n == 1)
return n;
else
return(fibonacci(n-1) + fibonacci(n-2));
}
int main()
{
int n, m= 0, i;
cout<<"enter the terms"<<endl;
cin>>n;
cout<<"fibonnaci series are "<<endl;
for(i = 1; i <= n; i++)
{
cout<<fibonacci(m)<<" ";
m++;
}
return 0;
}
```

Output:

```enter the terms:5
fibonnaci series are
0 1 1 2 3 ```

2nd Approach (Without recursion)

```#include<iostream>
using namespace std;
int main()
{
int first=0,second=1,third;
int num;
cout<<"enter the term "<<endl;
cin>>num;
cout<<first<<" "<<second<<" ";
for(int i=2;i<num;++i)
{
third=first+second;
cout<<third<<" " ;
first =second;
second=third;
}
return 0;
}  ```
```enter the term : 5
0 1 1 2 3 ```

Time Complexity:0(n)

space Complexity:O(1)