/
082-02.cr
123 lines (100 loc) · 1.7 KB
/
082-02.cr
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struct Mint
MOD = 1000000007i64
def self.zero
new
end
def self.raw(value : Int64)
result = new
result.value = value
result
end
getter value : Int64
def initialize
@value = 0i64
end
def initialize(value)
@value = value.to_i64 % MOD
end
def initialize(m : self)
@value = m.value
end
protected def value=(value : Int64)
@value = value
end
def ==(m : self)
value == m.value
end
def ==(m)
value == m
end
def +
self
end
def -
Mint.raw(value != 0 ? MOD - value : 0i64)
end
def +(v)
self + Mint.new(v)
end
def +(m : self)
x = value + m.value
x -= MOD if x >= MOD
Mint.raw(x)
end
def -(v)
self - Mint.new(v)
end
def -(m : self)
x = value - m.value
x += MOD if x < 0
Mint.raw(x)
end
def *(v)
self * Mint.new(v)
end
def *(m : self)
Mint.new(value * m.value)
end
def /(v)
self / Mint.new(v)
end
def /(m : self)
raise DivisionByZeroError.new if m.value == 0
a, b, u, v = m.value, MOD, 1i64, 0i64
while b != 0
t = a // b
a -= t * b
a, b = b, a
u -= t * v
u, v = v, u
end
Mint.new(value * u)
end
def **(exponent : Int)
t, x = self, Mint.raw(1i64)
while exponent > 0
x *= t if exponent & 1 == 1
t *= t
exponent >>= 1
end
x
end
delegate to_s, to: @value
delegate inspect, to: @value
end
struct Int
def to_m
Mint.new(self)
end
end
l, r = read_line.split.map(&.to_i64)
puts (1..19).sum { |d|
dl = {10i64**d.pred, l}.max
dr = d < 19 ? {10i64**d - 1, r}.min : r
if dl <= dr
cnt = (dr.to_m + dl) * (dr.to_m - dl + 1) / 2
cnt * d
else
Mint.zero
end
}