Let's say you have to go through three or four operations to get a final number, well, do it algebraically.
让我们说,你不得不通过3-4个操作,才能得到最终的数,好吧,用代数方法求解。
Up here I have n over two operations of size two. Up here I've got n over four operations of size four.
最下面有n个规模为1的操作,接着上面有n/2个规模为2的操作,再上面有n/4个规模为4的操作。
Down here, I've just got two things to merge, and then I've got things of size two to merge and then things of size four to merge. But notice a trade off. I have n operations if you like down there of size one.
但是n的大小是不同的,是吗?在这里我们只要合并两个元素,然后是合并长度为2的列表,接下来是合并长度为4的列表,但是观察一下之间的权衡关系。
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