Doubt in recursion relation

#1

Does the relation f(n)=f(n-1)+f(n-4) gives the wrong answer for n=4?

#2

No…you will have to make the base cases accordingly for the relation to work perfectly.

Base cases must be like this:

if (n < 1)
    return 0;//Because tiling not possible 

if (n < 4)
    return 1;//Because now you have only 1 way to tile and that is to tile vertically 

if (n == 4)
    return 2; //Because now you have 2 ways- either tile all vertically or tile all horizontally
#3

thanks a lot! my doubt has been resolved