def overlaps(t1_start,t1_end,t2_start,t2_end)
  if (t1_start - t2_end) * (t2_start - t1_end) >= 0
    return true #時間區間衝突
  else
    return false #時間區間未衝突
  end
end


t1_start = Time.new(2016,12,10,8,0)
t1_end = Time.new(2016,12,10,13,0)
t2_start = Time.new(2016,12,10,7,0)
t2_end = Time.new(2016,12,10,7,30)

puts overlaps(t1_start,t1_end,t2_start,t2_end)