Ways To Tile A Floor
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Given a floor of dimensions 2 x W and tiles of dimensions 2 x 1, the task is to find the number of ways the floor can be tiled. A tile can either be placed horizontally i.e as a 1 x 2 tile or vertically i.e as 2 x 1 tile. Print the answer modulo 109+7.


Example 1:

W = 3
We need 3 tiles to tile the board
of size  2 x 3. 
We can tile in 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.

Example 2:

W = 4
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.


Your Task:
You don't need to read input or print anything. Your task is to complete the function numberOfWays() which takes an Integer N as input and returns the answer.


Expected Time Complexity: O(N)
Expected Auxiliary Space: O(1)


1 <= N <= 105

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Ways To Tile A Floor

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