M3TILE - LATGACH3
In how many ways can you tile a 3xn rectangle with 2x1 dominoes? Here is a sample tiling of a 3x12 rectangle. Input consists of several test cases followed by a line containing -1. Each test case is a line containing an integer 0 ≤ n ≤ 30. For each test case, output one integer number giving the number of possible tilings.
2 8 12 -1
3 153 2131
When n == 0, there is exactly ONE way of tiling - not using any dominoes at all.
If the input number is 0 your program should output 1. I don't get it...