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#!/usr/bin/env ruby
require 'scanf'
class Array
def find_all_indices(elt)
return self.each_index.select { |i| self[i] == elt }
end
end
class Vector
attr_accessor :x, :y, :z
def initialize(array)
@x = array[0] || 0
@y = array[1] || 0
@z = array[2] || 0
end
def add!(vector)
@x += vector.x
@y += vector.y
@z += vector.z
end
def to_s
return "<#{@x},#{@y},#{@z}>"
end
end
class Particle
attr_accessor :pos, :vel, :acc
def initialize(p, v, a)
@pos = Vector.new(p)
@vel = Vector.new(v)
@acc = Vector.new(a)
@destroyed = false
end
def destroy!
@destroyed = true
end
def destroyed?
return @destroyed
end
def collides?(other)
return @pos.x == other.pos.x &&
@pos.y == other.pos.y &&
@pos.z == other.pos.z
end
def update!
@vel.add!(@acc)
@pos.add!(@vel)
end
def to_s
return "p=#{@pos}, v=#{@vel}, a=#{@acc}"
end
end
input = $stdin.readlines.map(&:chomp)
particles = input.map do |line|
px, py, pz, vx, vy, vz, ax, ay, az =
line.scanf("p=<%d,%d,%d>, v=<%d,%d,%d>, a=<%d,%d,%d>")
Particle.new([px, py, pz], [vx, vy, vz], [ax, ay, az])
end
times = 0
THE_LONG_RUN = 1000
loop do
collision = false
(0...particles.length).each do |i|
(i+1...particles.length).each do |j|
if particles[i].collides?(particles[j]) then
collision = true
particles[i].destroy!
particles[j].destroy!
end
end
end
if !collision then
times += 1
else
times = 0
end
break if times == THE_LONG_RUN
particles.each(&:update!)
particles = particles.reject(&:destroyed?)
end
p particles.length
|
