轮询和中断，白等了多少

运行下面这段程序，填写它打印出来的结果。

DEV = 1000
IRQ = 50

def by_poll(n):
    return n * DEV

def by_irq(n):
    return n * IRQ

def by_dma(n):
    return 2 * IRQ

wasted_poll = DEV
wasted_irq = IRQ
print(str(wasted_poll) + "/" + str(wasted_irq) + "/"
      + str(wasted_poll - wasted_irq))