uva-12627 - Erratic Expansion
出處 : https://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&page=show_problem&problem=4352
解題策略
uva-12627 - Erratic Expansion,Divide And Conquer,
若r小於等於2^(k-1),則f(k,r)=2*f(k-1,r) ,否則f(k,r)=2*3^(k-1)+2*f(k-1,r-2^(k-1))