Print Fibonacci sequence using 2 variables

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Print the Fibonacci sequence. The first Fibonacci numbers are:

C++

// Simple CPP Program to print Fibonacci 
// sequence
#include <iostream>
using std::cout;
void fib(int n)
{
    int a = 0, b = 1, c;
    if (n >= 0)
        cout << a << " ";
    if (n >= 1)
        cout << b << " ";
    for (int i = 2; i <= n; i++) {
        c = a + b;
        cout << c << " ";
        a = b;
        b = c;
    }
}
 
// Driver code
int main()
{
    fib(9);
    return 0;
}

Java

// Simple Java Program to print
// Fibonacci  sequence
import java.io.*;
class GFG {
 
static void fib(int n)
{
    int a = 0, b = 1, c;
    if (n >= 0)
        System.out.print( a + " ");
    if (n >= 1)
        System.out.print( b + " ");
    for (int i = 2; i <= n; i++) 
    {
        c = a + b;
        System.out.print( c + " ");
        a = b;
        b = c;
    }
}
 
    // Driver code
    public static void main (String[] args) 
    {
            fib(9);
    }
}
 
// This code is contributed by anuj_67.

Python3

# Simple Python3 Program to 
# print Fibonacci sequence
 
def fib(n):
    a = 0
    b = 1
    if (n >= 0):
        print(a, end=' ')
    if (n >= 1):
        print(b, end=' ')
    for i in range(2, n+1):
        c = a + b
        print(c, end=' ')
        a = b
        b = c
 
# Driver code
fib(9)
 
# This code is contributed 
# by Prasad Kshirsagar

C#

// Simple C# Program to print
// Fibonacci sequence
using System;
class GFG 
{
static void fib(int n)
{
    int a = 0, b = 1, c;
    if (n >= 0)
        Console.Write( a + " ");
    if (n >= 1)
        Console.Write( b + " ");
    for (int i = 2; i <= n; i++) 
    {
        c = a + b;
        Console.Write( c + " ");
        a = b;
        b = c;
    }
}
 
// Driver code
public static void Main () 
{
        fib(9);
}
}
 
// This code is contributed by anuj_67.

PHP

<?php
// Simple php Program to print
// Fibonacci sequence
 
function fib( $n)
{
    $a = 0; $b = 1; $c;
    if ($n >= 0)
        echo $a , " ";
    if ($n >= 1)
        echo $b , " ";
    for ( $i = 2; $i <= $n; $i++) 
    {
        $c = $a + $b;
        echo $c , " ";
        $a = $b;
        $b = $c;
    }
}
 
// Driver code
fib(9);
 
// This code is contributed by anuj_67.
?>

Javascript

<script>
    // Simple Javascript Program to print Fibonacci sequence
     
    function fib(n)
    {
        let a = 0, b = 1, c;
        if (n >= 0)
            document.write( a + " ");
        if (n >= 1)
            document.write( b + " ");
        for (let i = 2; i <= n; i++) 
        {
            c = a + b;
            document.write( c + " ");
            a = b;
            b = c;
        }
    }
     
    fib(9);
 
// This code is contributed by divyeshrabadiya07.
</script>

Output:

0 1 1 2 3 5 8 13 21 34

Time Complexity: O(n)

Auxiliary Space: O(1)

How to print using 2 variables instead of 3 variables?
The algorithm with 2 variables is:
1. print a+b.
2. add a to b.
3. assign b – a to a.

C++

// CPP Program to print Fibonacci sequence
// using 2 variables
#include <iostream>
using std::cout;
void fib(int n)
{
    int a = 0, b = 1;
    if (n >= 0)
        cout << a << " ";
    if (n >= 1)
        cout << b << " ";
    for (int i = 2; i <= n; i++) {
        cout << a + b << " ";
        b = a + b;
        a = b - a;
    }
}
 
// Driver code
int main()
{
    fib(9);
    return 0;
}

Java

// Java Program to print 
// Fibonacci sequence
// using 2 variables
import java.io.*;
class GFG {
     
static void fib(int n)
{
    int a = 0, b = 1;
    if (n >= 0)
        System.out.print(a + " ");
    if (n >= 1)
        System.out.print(b + " ");
    for (int i = 2; i <= n; i++) 
    {
        System.out.print(a + b + " ");
        b = a + b;
        a = b - a;
    }
}
 
    // Driver code
    public static void main (String[] args) 
    {
        fib(9);
    }
}
 
// This code is contributed by anuj_67.

Python3

# Simple Python3 Program to
# print Fibonacci sequence
# using 2 variables
 
def fib(n):
    a = 0
    b = 1
    if (n >= 0):
        print(a, end=' ')
    if (n >= 1):
        print(b, end=' ')
    for i in range(2, n+1):
        print(a + b, end=' ')
        b = a + b
        a = b - a
 
# Driver code
fib(9)
 
# This code is contributed by
# Prasad Kshirsagar

C#

// C# Program to print Fibonacci
// sequence using 2 variables
using System;
 
class GFG {
         
    static void fib(int n)
    {
        int a = 0, b = 1;
         
        if (n >= 0)
            Console.Write(a + " ");
        if (n >= 1)
            Console.Write(b + " ");
        for (int i = 2; i <= n; i++) 
        {
            Console.Write(a + b + " ");
            b = a + b;
            a = b - a;
        }
    }
 
    // Driver code
    public static void Main () 
    {
        fib(9);
    }
}
 
// This code is contributed by anuj_67.

PHP

<?php
// PHP Program to print Fibonacci sequence
// using 2 variables
 
function fib( $n)
{
    $a = 0; $b = 1;
    if ($n >= 0)
        echo $a , " ";
    if ($n >= 1)
        echo $b , " ";
    for ($i = 2; $i <= $n; $i++)
    {
        echo $a + $b , " ";
        $b = $a + $b;
        $a = $b - $a;
    }
}
 
    // Driver code
    fib(9);
     
// This code is contributed by anuj_67
?>

Javascript

<script>
    // Javascript Program to print Fibonacci sequence using 2 variables
     
    function fib(n)
    {
        let a = 0, b = 1;
          
        if (n >= 0)
            document.write(a + " ");
        if (n >= 1)
            document.write(b + " ");
        for (let i = 2; i <= n; i++)
        {
            document.write(a + b + " ");
            b = a + b;
            a = b - a;
        }
    }
     
    fib(9);
    
   // This code is contributed by decode2207.
</script>

Output :

0 1 1 2 3 5 8 13 21 34

Time Complexity: O(n)

Auxiliary Space: O(1)

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