UVa 10918 - Tri Tiling

10918 - Tri Tiling
Tri Tiling

Summary
Determine in how many ways can a 3xN rectangle be completely tiled with 2x1 dominoes.

Explanation
It's a typical problem on dynamic programming. One possible solution is described below.

Let $$f(n)$$ be the number of tilings of a 3xN rectangle (which is what we're looking for) and let $$g(n)$$ denote the number of tilings of a 3xN rectangle with one of its corner squares removed.

These functions satisfy the recurrent relations: $$f(n)=f(n-2)+2g(n-1), g(n)=f(n-1)+g(n-2).$$ The formulas can be illustrated as follows:

f(n)  =  f(n-2)   +  g(n-1)  +  g(n-1)
 * AA*******  AA******   A*******
 * = BB******* + B******* + A*******
 * CC*******  B*******   BB******

*******   ********    CC****** g(n)  =   f(n-1)  +   g(n-2)
 * A********  AA*******
 * = A******** + BB*******

The boundary values for the relations are: $$f(0) = 1, f(1) = 0, g(0) = 0, g(1) = 1.$$

For any odd value of N, the number of tilings of a 3xN rectangle is 0.

Input
0 1 2 8 12 30 -1

Output
1 0 3 153 2131 299303201