ABC260 C - Changing Jewels

提出

code: python

n, x, y = list(map(int, input().split()))

# Rn * 1

# Rn => Rn-1 + Bn * X

# Bn => Rn-1 + Bn-1 * Y

# Rn => Rn-1 + (Rn-1 + Bn-1 * Y) * X => Rn-1 * (X + 1) + Bn-1 * (X * Y)

# 2 3 4

def exchange(level, rnum):

if level == 2:

return rnum * x * y

elif level == 1:

return 0

else:

return exchange(level - 1, x+1)

print(exchange(n, 1))

解答

code: python

n, x, y = list(map(int, input().split()))

# Rn => Rn-1 + Bn * X

# Bn => Rn-1 + Bn-1 * Y

def exchange(level, is_red):

if level == 1:

return 0 if is_red else 1

if is_red:

return exchange(level - 1, True) + exchange(level, False) * x

else:

return exchange(level - 1, True) + exchange(level - 1, False) * y

print(exchange(n, True))

メモ

提出

TLE

code: python

n, x, y = list(map(int, input().split()))

# R(N) -> R(N-1) + B(N) * X

# B(N) -> R(N-1) + B(N-1) * Y

# R(N) -> (X+1) R(N-1) + XY B(N-1)

# 2 3 4

# R(2) -> 4 R(1) + 12 B(1)

def red(level, num):

if level == 1:

return

for _ in range(num):

red(level-1, x+1)

blue(level-1, x*y)

def blue(level, num):

if level == 1:

return

for _ in range(num):

red(level-1, 1)

blue(level-1, y)

red(n, 1)