But he says the United States can't solve the world's problems alone and it is time for all U.N.
VOA: standard.2009.09.23
And we said that was log rhythmic, took log n time where n is the size of the list.
当列表的长度为n的时候,整个算法耗时log,n的时间。
N log N is not nearly as good as log N. As a sanity check, what algorithm have we seen that runs in log N time?
而N,log,N和log,N并不一样,我们之前探讨过的哪个算法其时间复杂度是log,N呢?
The U.N.climate change talks opened Monday with warnings that time was running out on reaching a deal.
VOA: standard.2009.09.28
So I have n operations log n times, n log n there we go, n log n. Took us a long time to get there, but it's a nice algorithm to have.
所以我log,n遍的n次操作,就得到了,虽然花了不少时间得到了这个结论。
Mr.Obama urged Tehran to agree to a U.N.proposal to ship its uranium abroad for processing, adding that time for diplomacy on the issue is running out.
VOA: standard.2009.11.16
n So the velocity is given by this product of the quantum number n Planck constant 2 pi mass of the electron time the radius of the orbit, which itself is a function of n.
速度是量子数,普朗克常数2π乘以轨道半径的值,它自身也是n的函数。
Thetop U.N.climate official Yvo de Boer said it is time to act.
VOA: standard.2009.12.06
And we talked about the equation you can use for radial nodes last time, and that's just n minus 1 minus l.
我们讲过这个用于,计算径向节点的方程,也就是n减去l减去1
Yvo de Boer,the U.N.'s top climate change official, told delegates there was still time to break deadlocks, but he said countries that could be more ambitious should act now.
VOA: standard.2009.09.28
But that merging process only takes N steps, N*log N so that's N times log of N. Now, it's a little tricky to reason through this perhaps the first time, let's just take a very simple example and see if we can do a little sanity check here.
但这个合并过程只需要N步,所以时间复杂度是,第一次对此进行推论可能会有点儿棘手,我们举一个简单的例子,看看我们能否做一些完整性的检查。
I could still do the linear case, which is order n or I could say, look, take the list, let's sort it and then search it. But in that case we said well to sort it was going to take n log n time, assuming I can do that.
我仍然可以做O的线性搜索,或者也可以以这个列表为例,我们先将其进行排序,然后再进行查找,但是在这种情况下,要花费n,log,n的时间去对其进行排序。
Once I have it sorted I can search it in log n time, but that's still isn't as good as just doing n. And this led to this idea of amortization, which is I need to not only factor in the cost, but how am I going to use it?
一旦对其完成排序,就可以在log,n的时间内对其完成搜索,但是这样做仍然不如n的复杂度,这样做引出了耗时分摊的想法,这时不仅需要考虑耗时的因素?
And then one of the things that I suggested was that if we could figure out some way to order it, and in particular, if we could order it in n log n time, and we still haven't done that, but if we could do that, then we said the complexity changed a little bit.
这就涉及到了排序,如果可以想出一种来将其进行排序,甚至可以在n,log,n的时间内完成,虽然目前我们没做这件事,但是一旦开始做这件事,那么复杂性就是发生一些变化。
On the other hand, if I want to sort it first, OK, if I want to do sort and search, I want to sort it, it's going to take n log n time to sort it, and having done that, then I can search it in log n time.
我先排序,好的,如果我想排序再搜索,我要排序,这需要花n,log,n时间排序,然后做完了,我们能花log,n时间搜索,啊,哪一种更好呢?恩,呵呵。
It at least does corroborate the claim that merge sort N*log N as we argue intuitively is in fact, N log N in running time.
但这至少证实了归并排序,的时间复杂度为。
Remember, we saw that last time looking at the binary numbers. 2 to the n is a big number.
还记得吗,我们上次看过的二进制数,从2到n是一个很大的数。
So in other words, every time I merge the point that I kept emphasizing verbally there and that I'm only touching each number once, means that we have to account for the amount of time it takes to merge N which is going to be just N. Now, this is again one of these cyclical answers.
换言之,之前在做合并时,我不停地强调,对每个数字我只碰了一次,这就是说,我们要记录合并所花的时间量,也就是这里的,这又是一种循环性的答案。
So the running time of the problem where the input is T of size N as expressed here formulaically, T of N, the running time of an algorithm, given an input of size N. You know what?
因此一个输入为N的问题的运行时间,在这儿的公式表示为,如果输入为N,那么此算法的运行时间,是多少呢?
to the n, every value in the 1 bit vector we looked at last time is either 0 or 1. So it's a binary n number of n bits, 2 to the n.
从2到n,我们上次看到的,位向量的每个值不是0就是,所以它是n,比特的二进制数,从2到。
So this line or these lines of code up here are arguably constant time steps to say if N is less than 2 in return, that it will always take maybe one step, maybe two steps, some number of fixed CPU cycles.
如果N小于2并返回,那么这些行所对应的代码,通常只需要执行一步,或者两步,具体数字与CPU周期有关。
If I'm using algorithm that I'm now calling merge sort, T the running time involved in sorting N elements, T of N, you know, is just the same as running the algorithm for the right half, plus what's this plus N come from?
如果我用归并排序算法,对N个元素其运行时间,就等于此算法一半元素的运行时间,另一半的运行时间,再加上N,这个N是什么呢?
I think most and you are familiar with the Aufbau or the building up principle, you probably have seen it quite a bit in high school, and this is the idea that we're filling up our energy states, again, which depend on both n and l, one electron at a time starting with that lowest energy and then working our way up into higher and higher orbitals.
我认为你们大多数熟悉奥弗堡,或者构建原理,你们可能,在高中见过它,又一次,这是我们填充能级的观点,与n和l有关,一个电子每次从,最低的能级开始,然后以我们的方式上升到,更高更高的轨道。
Like what the heck have we been spending our time for-- our time on with Bubble Sort and with Selection Sort and in fact there's plenty of other N squared sorts that we're not even gonna bother looking at.
真见鬼,我们竟然在-,冒泡排序和选择排序上花时间,而事实上,还有很多我们根本都不想考虑的,复杂度为N平方的排序方法。
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