Designing Code for Fibonacci Sequence without Recursion

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.


Designing Code for 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)

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;
			last = 1;
		secondLast = last;
		last = val;

int main()
	return 0;


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