# Print Fibonacci sequence using 2 variables

• Difficulty Level : Easy
• Last Updated : 26 Nov, 2021

Print the Fibonacci sequence. The first Fibonacci numbers are:

## C++

 `// Simple CPP Program to print Fibonacci``// sequence``#include ``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

 `= 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

 ``

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.
3. assign b – a to a.

## C++

 `// CPP Program to print Fibonacci sequence``// using 2 variables``#include ``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

 `= 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

 ``

Output :

`0 1 1 2 3 5 8 13 21 34`

Time Complexity: O(n)

Auxiliary Space: O(1)

My Personal Notes arrow_drop_up