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atcoder/src/Math.cr
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- Last update: 2022-04-16 07:49:21+00:00
Required by
atcoder/src/ModInt.cr
- atcoder/src/Prime.cr
- spec/math/dynamic_mint_spec.cr
- spec/math/mint_spec.cr
- src/math/dynamic_mint.cr
- src/math/euler.cr
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# ac-library.cr by hakatashi https://github.com/google/ac-library.cr
#
# Copyright 2022 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
module AtCoder
# Implements [ACL's Math library](https://atcoder.github.io/ac-library/master/document_en/math.html)
module Math
def self.extended_gcd(a, b)
last_remainder, remainder = a.abs, b.abs
x, last_x, y, last_y = 0_i64, 1_i64, 1_i64, 0_i64
while remainder != 0
new_last_remainder = remainder
quotient, remainder = last_remainder.divmod(remainder)
last_remainder = new_last_remainder
x, last_x = last_x - quotient * x, x
y, last_y = last_y - quotient * y, y
end
return last_remainder, last_x * (a < 0 ? -1 : 1)
end
# Implements atcoder::inv_mod(value, modulo).
def self.inv_mod(value, modulo)
gcd, inv = extended_gcd(value, modulo)
if gcd != 1
raise ArgumentError.new("#{value} and #{modulo} are not coprime")
end
inv % modulo
end
# Simplified AtCoder::Math.pow_mod with support of Int64
def self.pow_mod(base, exponent, modulo)
if exponent == 0
return base.class.zero + 1
end
if base == 0
return base
end
b = exponent > 0 ? base : inv_mod(base, modulo)
e = exponent.abs
ret = 1_i64
while e > 0
if e % 2 == 1
ret = mul_mod(ret, b, modulo)
end
b = mul_mod(b, b, modulo)
e //= 2
end
ret
end
# Caluculates a * b % mod without overflow detection
@[AlwaysInline]
def self.mul_mod(a : Int64, b : Int64, mod : Int64)
if mod < Int32::MAX
return a * b % mod
end
# 31-bit width
a_high = (a >> 32).to_u64
# 32-bit width
a_low = (a & 0xFFFFFFFF).to_u64
# 31-bit width
b_high = (b >> 32).to_u64
# 32-bit width
b_low = (b & 0xFFFFFFFF).to_u64
# 31-bit + 32-bit + 1-bit = 64-bit
c = a_high * b_low + b_high * a_low
c_high = c >> 32
c_low = c & 0xFFFFFFFF
# 31-bit + 31-bit
res_high = a_high * b_high + c_high
# 32-bit + 32-bit
res_low = a_low * b_low
res_low_high = res_low >> 32
res_low_low = res_low & 0xFFFFFFFF
# Overflow
if res_low_high + c_low >= 0x100000000
res_high += 1
end
res_low = (((res_low_high + c_low) & 0xFFFFFFFF) << 32) | res_low_low
(((res_high.to_i128 << 64) | res_low) % mod).to_i64
end
@[AlwaysInline]
def self.mul_mod(a, b, mod)
typeof(mod).new(a.to_i64 * b % mod)
end
# Implements atcoder::crt(remainders, modulos).
def self.crt(remainders, modulos)
raise ArgumentError.new unless remainders.size == modulos.size
total_modulo = 1_i64
answer = 0_i64
remainders.zip(modulos).each do |(remainder, modulo)|
gcd, p = extended_gcd(total_modulo, modulo)
if (remainder - answer) % gcd != 0
return 0_i64, 0_i64
end
tmp = (remainder - answer) // gcd * p % (modulo // gcd)
answer += total_modulo * tmp
total_modulo *= modulo // gcd
end
return answer % total_modulo, total_modulo
end
# Implements atcoder::floor_sum(n, m, a, b).
def self.floor_sum(n, m, a, b)
n, m, a, b = n.to_i64, m.to_i64, a.to_i64, b.to_i64
res = 0_i64
if a < 0
a2 = a % m
res -= n * (n - 1) // 2 * ((a2 - a) // m)
a = a2
end
if b < 0
b2 = b % m
res -= n * ((b2 - b) // m)
b = b2
end
res + floor_sum_unsigned(n, m, a, b)
end
private def self.floor_sum_unsigned(n, m, a, b)
res = 0_i64
loop do
if a >= m
res += n * (n - 1) // 2 * (a // m)
a = a % m
end
if b >= m
res += n * (b // m)
b = b % m
end
y_max = a * n + b
break if y_max < m
n = y_max // m
b = y_max % m
m, a = a, m
end
res
end
end
end# ac-library.cr by hakatashi https://github.com/google/ac-library.cr
#
# Copyright 2022 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
module AtCoder
# Implements [ACL's Math library](https://atcoder.github.io/ac-library/master/document_en/math.html)
module Math
def self.extended_gcd(a, b)
last_remainder, remainder = a.abs, b.abs
x, last_x, y, last_y = 0_i64, 1_i64, 1_i64, 0_i64
while remainder != 0
new_last_remainder = remainder
quotient, remainder = last_remainder.divmod(remainder)
last_remainder = new_last_remainder
x, last_x = last_x - quotient * x, x
y, last_y = last_y - quotient * y, y
end
return last_remainder, last_x * (a < 0 ? -1 : 1)
end
# Implements atcoder::inv_mod(value, modulo).
def self.inv_mod(value, modulo)
gcd, inv = extended_gcd(value, modulo)
if gcd != 1
raise ArgumentError.new("#{value} and #{modulo} are not coprime")
end
inv % modulo
end
# Simplified AtCoder::Math.pow_mod with support of Int64
def self.pow_mod(base, exponent, modulo)
if exponent == 0
return base.class.zero + 1
end
if base == 0
return base
end
b = exponent > 0 ? base : inv_mod(base, modulo)
e = exponent.abs
ret = 1_i64
while e > 0
if e % 2 == 1
ret = mul_mod(ret, b, modulo)
end
b = mul_mod(b, b, modulo)
e //= 2
end
ret
end
# Caluculates a * b % mod without overflow detection
@[AlwaysInline]
def self.mul_mod(a : Int64, b : Int64, mod : Int64)
if mod < Int32::MAX
return a * b % mod
end
# 31-bit width
a_high = (a >> 32).to_u64
# 32-bit width
a_low = (a & 0xFFFFFFFF).to_u64
# 31-bit width
b_high = (b >> 32).to_u64
# 32-bit width
b_low = (b & 0xFFFFFFFF).to_u64
# 31-bit + 32-bit + 1-bit = 64-bit
c = a_high * b_low + b_high * a_low
c_high = c >> 32
c_low = c & 0xFFFFFFFF
# 31-bit + 31-bit
res_high = a_high * b_high + c_high
# 32-bit + 32-bit
res_low = a_low * b_low
res_low_high = res_low >> 32
res_low_low = res_low & 0xFFFFFFFF
# Overflow
if res_low_high + c_low >= 0x100000000
res_high += 1
end
res_low = (((res_low_high + c_low) & 0xFFFFFFFF) << 32) | res_low_low
(((res_high.to_i128 << 64) | res_low) % mod).to_i64
end
@[AlwaysInline]
def self.mul_mod(a, b, mod)
typeof(mod).new(a.to_i64 * b % mod)
end
# Implements atcoder::crt(remainders, modulos).
def self.crt(remainders, modulos)
raise ArgumentError.new unless remainders.size == modulos.size
total_modulo = 1_i64
answer = 0_i64
remainders.zip(modulos).each do |(remainder, modulo)|
gcd, p = extended_gcd(total_modulo, modulo)
if (remainder - answer) % gcd != 0
return 0_i64, 0_i64
end
tmp = (remainder - answer) // gcd * p % (modulo // gcd)
answer += total_modulo * tmp
total_modulo *= modulo // gcd
end
return answer % total_modulo, total_modulo
end
# Implements atcoder::floor_sum(n, m, a, b).
def self.floor_sum(n, m, a, b)
n, m, a, b = n.to_i64, m.to_i64, a.to_i64, b.to_i64
res = 0_i64
if a < 0
a2 = a % m
res -= n * (n - 1) // 2 * ((a2 - a) // m)
a = a2
end
if b < 0
b2 = b % m
res -= n * ((b2 - b) // m)
b = b2
end
res + floor_sum_unsigned(n, m, a, b)
end
private def self.floor_sum_unsigned(n, m, a, b)
res = 0_i64
loop do
if a >= m
res += n * (n - 1) // 2 * (a // m)
a = a % m
end
if b >= m
res += n * (b // m)
b = b % m
end
y_max = a * n + b
break if y_max < m
n = y_max // m
b = y_max % m
m, a = a, m
end
res
end
end
end