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| #!/usr/bin/env ruby
# DNA?
# Kanwei Li, 2009
# Make sure input file exists and read from it
filename = ARGV[0]
unless filename && File.exist?(filename)
puts "error: must specify a valid input file"
exit
end
input = File.open(filename)
dna_size = input.gets.to_i
input.pos += dna_size + (dna_size / 80) + (dna_size % 80 == 0 ? 0 : 1)
dots = []
input.gets.to_i.times { |idx|
dots << input.gets.split(/\W+/).collect { |i| i.to_i }
}
s_by_finish = dots.sort_by { |b| b[1] }
p_i = {}
def search(container, start, high)
# puts "Searching end < #{start}"
low = 0
best = nil
while low <= high
mid = (low + high) / 2
finish = container[mid][1] # finish
if finish >= start
# went too far, go down
high = mid - 1
else
# good so far, try going higher
# puts "#{finish} (#{mid}) < #{start}"
best = mid
low = mid + 1
end
end
# puts "Best: #{best}"
return best
end
s_by_finish.each_with_index { |s, i|
# puts i if i % 10000 == 0
p = search(s_by_finish, s[0], i-1)
p_i[i] = p if p
}
def max(a,b)
return (a > b ? a : b)
end
mem = [0]
s_by_finish.each_with_index { |t, i|
pi = p_i[i] ? mem[ p_i[i] ] : 0
mem[i] = max(t[2] + pi, mem[i-1])
}
puts mem[-1]
|
