**What’s a Fibonacci sequence:**

Fibonacci sequence is a kind of sequence in which every subsequent number is sum of the previous two numbers i.e.

0,1,1,2,3,5,8,13,21,34,55,89,144

**Designing Code forÂ Fibonacci sequence:**

Now let’s write a code to display this sequence but without recursion. Because with recursion it easy i.e. just use the concept,

F(i) = F(i – 1) + F(i -2)

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But it takes a lot of time for large numbers because of repeated calculations in recursion.

So, let’s do it without recursion.

**Algo to create a Fibonacci sequence of N numbers without recursion:**

- Create 2 variables that will store the value of last and second last number.
- Initialize both the variables with 0.
- Now start a loop till N and for every i-th index,
- Print Sum of last and second last i.e SUM = LAST + SECOND_LAST
- Assign last to second last i.e. SECOND_LAST = LAST
- Assign Sum to last i.e. LAST = SUM

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Let’s see the code,

#include <iostream> void fibonacci(int n) { int last = 0; int secondLast = 0; for(int i = 0; i < n ; i++) { int val = last + secondLast; std::cout<<val<<","; if(!val) last = 1; secondLast = last; last = val; } } int main() { fibonacci(20); std::cout<<std::endl; return 0; }