【ABC 115】D. Christmas を視覚的に見て分かりやすく考える

問題文他

バーガーの厚さとパティの枚数の関係

ソースコード

N,K=map(int,input().split())
 
thickness=[1]*(N+1)
Npatty=[1]*(N+1)
 
for i in range(1,N+1):
  thickness[i]=2*thickness[i-1]+3
  Npatty[i]=2*Npatty[i-1]+1
 
#print(thickness,Npatty)  

def countpatty(N,K):
  
  if K==1:

    if N==0:
      return 1
    else:
      return 0

  if 2<=K<=thickness[N-1]+1:
    return countpatty(N-1,K-1)

  if K==thickness[N-1]+2:
    return Npatty[N-1]+1

  if thickness[N-1]+3<=K<=thickness[N]-1:
    return Npatty[N-1]+1+countpatty(N-1,K-2-thickness[N-1])

  if K==thickness[N]:
    return 2*Npatty[N-1]+1
 
print(countpatty(N,K))