# Fibonacci series in Java

Feb. 28, 2021 141

The Fibonacci series is a series of numbers where a number is the addition of the last two numbers, starting with 0, and 1.

The Fibonacci Sequence: 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55…

Starting with 0 and 1 as the first and second terms, the third term is addition of the first two i.e., 0+1; third term is addition of the first and third terms i.e., 1+1 and so on.

## Problem Description

Write a Program to display the user-defined N number of the Fibonacci series terms.

​Input:7

Output:0 1 1 2 3 5 8

Input:10

Output:0 1 1 2 3 5 8 13 21 34

## Approach

The Fibonacci numbers are the numbers in the sequence such that the current number will be the sum of the previous two numbers i.e., F(n) = F(n-1) + F(n-2).
And given that F(1)=0 and F(2)=1.
• ​Take the number as input from the user.
• Initialize the first number with 0 and the second number with 1.
• Now, start moving iteratively till the Nth number. To calculate the current number, equate it to sum of the previous two numbers. And continue to move further.

## Pseudocode

Input=N
a=0
b=1
For i=1 till i less than equal to N:
print(a)
c=a+b
a=b
b=c


Let's run few iterations of this code.

Initially, we will have the sequence 0, 1. In the first iteration, c will be the next term and we will change the values of a and b.

Proceeding with the next iteration, c will again be the next term and again a and b will be updated as shown below.

## Program

package codesdope;
import java.util.*;
public class codesdope
{
public static void main(String[] args)
{
Scanner sc=new Scanner(System.in);
int count=sc.nextInt();
int num1 = 0, num2 = 1;
for(int i=1;i<=count;i++)
{
System.out.print(num1+" ");
int sum = num1 + num2;
num1 = num2;
num2 = sum;
}
}
}


10

0 1 1 2 3 5 8 13 21 34

Let us dry run the code:

For N=7
• a=0
b=1
• i=1
print(a)=0
c=a+b=1
a=b=1
b=c=1
• i=2
print(a)=1
c=a+b=2
a=b=1
b=c=2
• i=3
print(a)=1
c=a+b=3
a=b=2
b=c=3
• i=4
print(a)=2
c=a+b=5
a=b=3
b=c=5
• i=5
print(a)=3
c=a+b=8
a=b=5
b=c=8
• i=6
print(a)=5
c=a+b=13
a=b=8
b=c=13
• i=7
print(a)=8
c=a+b=21
a=b=13
b=c=21

Liked the post?
Editor's Picks
0 COMMENT