Your browser (Unknown 0) is no longer supported. Some parts of the website may not work correctly. Please update your browser.

UPCOMING CHALLENGES:

CURRENT CHALLENGES:

The OLX Group challenge

PAST CHALLENGES

Silver 2020

Palladium 2020

Rhodium 2019

Ruthenium 2019

Technetium 2019

Molybdenum 2019

Niobium 2019

Zirconium 2019

Yttrium 2019

Strontium 2019

Rubidium 2018

Arsenicum 2018

Krypton 2018

Bromum 2018

Future Mobility

Grand Challenge

Digital Gold

Selenium 2018

Germanium 2018

Gallium 2018

Zinc 2018

Cuprum 2018

Cutting Complexity

Nickel 2018

Cobaltum 2018

Ferrum 2018

Manganum 2017

Chromium 2017

Vanadium 2016

Titanium 2016

Scandium 2016

Calcium 2015

Kalium 2015

Argon 2015

Chlorum 2014

Sulphur 2014

Phosphorus 2014

Silicium 2014

Aluminium 2014

Magnesium 2014

Natrium 2014

Neon 2014

Fluorum 2014

Oxygenium 2014

Nitrogenium 2013

Carbo 2013

Boron 2013

Beryllium 2013

Lithium 2013

Helium 2013

Hydrogenium 2013

Omega 2013

Psi 2012

Chi 2012

Phi 2012

Upsilon 2012

Tau 2012

Sigma 2012

Rho 2012

Pi 2012

Omicron 2012

Xi 2012

Nu 2011

Mu 2011

Lambda 2011

Kappa 2011

Iota 2011

Theta 2011

Eta 2011

Zeta 2011

Epsilon 2011

Delta 2011

Gamma 2011

Beta 2010

Alpha 2010

Count tilings of a narrow but long rectangle with tiles of size 1x1 or 2x2.

A board consisting of squares arranged into N rows and M columns is given. A *tiling* of this board is a pattern of tiles that covers it. A tiling is *interesting* if:

- only tiles of size 1x1 and/or 2x2 are used;
- each tile of size 1x1 covers exactly one whole square;
- each tile of size 2x2 covers exactly four whole squares;
- each square of the board is covered by exactly one tile.

For example, the following images show a few interesting tilings of a board of size 4 rows and 3 columns:

Two interesting tilings of a board are *different* if there exists at least one square on the board that is covered with a tile of size 1x1 in one tiling and with a tile of size 2x2 in the other. For example, all tilings shown in the images above are different.

Write a function:

class Solution { public int solution(int N, int M); }

that, given two integers N and M, returns the remainder modulo 10,000,007 of the number of different interesting tilings of a board of size N rows and M columns.

For example, given N = 4 and M = 3, the function should return 11, because there are 11 different interesting tilings of a board of size 4 rows and 3 columns:

Write an ** efficient** algorithm for the following assumptions:

- N is an integer within the range [1..1,000,000];
- M is an integer within the range [1..7].

Copyright 2009–2020 by Codility Limited. All Rights Reserved. Unauthorized copying, publication or disclosure prohibited.