http://acm.mipt.ru/judge/problems.pl?problem=071

cable.rb

data = STDIN.read
data = data.scan( /\d+/ ).map{ |is| is.to_i }
N = data.shift
K = data.shift
cables = data.clone
max = cables.max
max2 = 2 ** (Math::log(max+1) / Math::log(2)).ceil
l = step = max2 / 2
max_l = 0
while step > 0 do
	count = 0
	cables = data.clone
	cables.each do |cable|
		while cable >= l do
			cable -= l
			count += 1
			cable.to_s + ' ' + l.to_s + ' ' + count.to_s
			break if count == K
		end
		break if count == K
	end
	step /= 2
	if count == K
		max_l = l
		l += step
	elsif
		l -= step
	end
end
print max_l