# Fibbinary Numbers (No consecutive 1s in binary)

Given N, check if the number is Fibbinary Number or not. Fibbinary numbers are integers whose binary representation contains no consecutive ones.

Examples :

```Input : 10
Output : YES
Explanation: 1010 is the binary representation
of 10 which does not contains any
consecutive 1's.

Input : 11
Output : NO
Explanation: 1011 is the binary representation
of 11, which contains consecutive
1's
```

## Recommended: Please try your approach on {IDE} first, before moving on to the solution.

The idea to do this is to right shift the number, till n!=0. For every binary representation of 1, check if the last bit found was 1 or not. Get the last bit of binary representation of the integer by doing a (n&1). If the last bit of the binary representation is 1 and the previous bit before doing a right shift was also one, we encounter consecutive 1’s. So we come to the conclusion that it is not a fibonnary number.

Some of the first few Fibonnary numbers are:

`0, 2, 4, 8, 10, 16, 18, 20.......`

## CPP

 `// CPP program to check if a number  ` `// is fibinnary number or not ` `#include ` `using` `namespace` `std; ` ` `  `// function to check if binary  ` `// representation of an integer  ` `// has consecutive 1s ` `bool` `checkFibinnary(``int` `n)  ` `{ ` `    ``// stores the previous last bit ` `    ``// initially as 0 ` `    ``int` `prev_last = 0; ` `    `  `    ``while` `(n)  ` `    ``{ ` `        ``// if current last bit and  ` `        ``// previous last bit is 1 ` `        ``if` `((n & 1) && prev_last) ` `            ``return` `false``; ` `     `  `        ``// stores the last bit ` `        ``prev_last = n & 1; ` `     `  `        ``// right shift the number ` `        ``n >>= 1; ` `    ``} ` ` `  `    ``return` `true``; ` `} ` ` `  `// Driver code to check above function ` `int` `main() ` `{ ` `    ``int` `n = 10; ` `    ``if` `(checkFibinnary(n)) ` `        ``cout << ``"YES"``; ` `    ``else` `        ``cout << ``"NO"``; ` `    ``return` `0; ` `} `

## Java

 `// Java program to check if a number  ` `// is fibinnary number or not ` `class` `GFG { ` `     `  `    ``// function to check if binary  ` `    ``// representation of an integer  ` `    ``// has consecutive 1s ` `    ``static` `boolean` `checkFibinnary(``int` `n)  ` `    ``{ ` ` `  `        ``// stores the previous last bit ` `        ``// initially as 0 ` `        ``int` `prev_last = ``0``; ` `         `  `        ``while` `(n != ``0``)  ` `        ``{ ` `             `  `            ``// if current last bit and  ` `            ``// previous last bit is 1 ` `            ``if` `((n & ``1``) != ``0` `&& prev_last != ``0``) ` `             `  `                ``return` `false``; ` `         `  `            ``// stores the last bit ` `            ``prev_last = n & ``1``; ` `         `  `            ``// right shift the number ` `            ``n >>= ``1``; ` `        ``} ` `     `  `        ``return` `true``; ` `    ``} ` `     `  `    ``// Driver code to check above function ` `    ``public` `static` `void` `main(String[] args) ` `    ``{ ` `        ``int` `n = ``10``; ` ` `  `        ``if` `(checkFibinnary(n) == ``true``) ` `            ``System.out.println(``"YES"``); ` `        ``else` `            ``System.out.println(``"NO"``); ` `    ``} ` `} ` ` `  `// This code is contributed by ` `// Smitha Dinesh Semwal `

## Python3

 `# Python 3 program to check if a ` `# number is fibinnary number or  ` `# not ` ` `  `# function to check if binary  ` `# representation of an integer  ` `# has consecutive 1s ` `def` `checkFibinnary(n):  ` ` `  `    ``# stores the previous last bit ` `    ``# initially as 0 ` `    ``prev_last ``=` `0` `     `  `    ``while` `(n):  ` `     `  `        ``# if current last bit and  ` `        ``# previous last bit is 1 ` `        ``if` `((n & ``1``) ``and` `prev_last): ` `            ``return` `False` `     `  `        ``# stores the last bit ` `        ``prev_last ``=` `n & ``1` `     `  `        ``# right shift the number ` `        ``n >>``=` `1` `     `  ` `  `    ``return` `True` ` `  `# Driver code ` `n ``=` `10` ` `  `if` `(checkFibinnary(n)): ` `    ``print``(``"YES"``) ` `else``: ` `    ``print``(``"NO"``) ` ` `  `# This code is contributed by Smitha Dinesh Semwal `

## C#

 `// C# program to check if a number  ` `// is fibinnary number or not ` `using` `System; ` ` `  `class` `GFG { ` `     `  `    ``// function to check if binary  ` `    ``// representation of an integer  ` `    ``// has consecutive 1s ` `    ``static` `bool` `checkFibinnary(``int` `n)  ` `    ``{ ` ` `  `        ``// stores the previous last bit ` `        ``// initially as 0 ` `        ``int` `prev_last = 0; ` `         `  `        ``while` `(n != 0)  ` `        ``{ ` `             `  `            ``// if current last bit and  ` `            ``// previous last bit is 1 ` `            ``if` `((n & 1) != 0 && prev_last != 0) ` `             `  `                ``return` `false``; ` `         `  `            ``// stores the last bit ` `            ``prev_last = n & 1; ` `         `  `            ``// right shift the number ` `            ``n >>= 1; ` `        ``} ` `     `  `        ``return` `true``; ` `    ``} ` `     `  `    ``// Driver code to check above function ` `    ``public` `static` `void` `Main() ` `    ``{ ` `        ``int` `n = 10; ` ` `  `        ``if` `(checkFibinnary(n) == ``true``) ` `            ``Console.WriteLine(``"YES"``); ` `        ``else` `            ``Console.WriteLine(``"NO"``); ` `    ``} ` `} ` ` `  `// This code is contributed by vt_m. `

## PHP

 `>= 1; ` `    ``} ` `    ``return` `true; ` `} ` ` `  `// Driver code ` `\$n` `= 10; ` `if` `(checkFibinnary(``\$n``)) ` `    ``echo` `"YES"``; ` `else` `    ``echo` `"NO"``; ` ` `  `// This code is contributed by mits  ` `?> `

Output :

```YES
```

Time Complexity: O( log(n) )

Fibbinary Numbers (No consecutive 1s in binary) – O(1) Approach

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