BZOJ1002[FJOI2007] Rotavirus

BZOJ1002[FJOI2007] Rotavirus

Test instructions

The rule of N-rotavirus is to delete several edges in an n-wheeled base, so that there is a unique information channel between the atoms, for example, a total of 16
The same 3 rotavirus, as shown in

Now given n, calculate how many different N-rotavirus viruses are. n<=100

Exercises

Formula: F[i]=f[i-1]*3-f[i-2]+2,i≥3,f[1]=1,f[2]=5. (I admit I'm a qaq because I don't know anything about matrix-Tree theorem ~

It was high precision, and I dropped it with the Python water ...

Code:

1n=Int (raw_input ())2A=13B=54  forIinchRange (3,n+1):5C=b*3-a+26A=b7b=C8 ifN==1:9     PrintaTen Else: One     PrintB

20160814

BZOJ1002[FJOI2007] Rotavirus