InterviewBit Academy is now Scaler!
InterviewBit Academy is now Scaler Academy!

Tiling Problem

Given a 2 x A board and tiles of size 2 x 1.

Count the number of ways to tile the given board using the 2 x 1 tiles.
A tile can either be placed horizontally i.e., as a 1 x 2 tile or vertically i.e., as 2 x 1 tile.

Since the number of ways can be very large,
return the number of ways modulo (109+7).

Input Format

The only argument given is an integer A.

Output Format

Return the number of ways to tile the given board modulo (10^9+7).


1 <= A <= 10^6

For Example

Input 1:
    A = 3
Output 1:
    Explanation 1:
        We need 3 tiles to tile the board of size  2 x 3. 
        We can tile the board using following ways
            1. Place all 3 tiles vertically. 
            2. Place first tile vertically and remaining 2 tiles horizontally.
            3. Place first 2 tiles horizontally and remaining tiles vertically

Input 2:
    A = 4
Output 2:
    Explanation 2:
        For a 2 x 4 board, there are 5 ways
            1. All 4 vertical
            2. All 4 horizontal
            3. First 2 vertical, remaining 2 horizontal
            4. First 2 horizontal, remaining 2 vertical
            5. Corner 2 vertical, middle 2 horizontal
NOTE: You only need to implement the given function. Do not read input, instead use the arguments to the function. Do not print the output, instead return values as specified. Still have a doubt? Checkout Sample Codes for more details.
Start solving Tiling Problem on Interview Code Editor
Sign Up
to access hints and editorial solutions for Tiling Problem


Click here to start solving coding interview questions