在算法分析中,O(log n) 和 O(log n + 1) 之间的区别。

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英文:

Difference between O(log n) and O(log n +1)

问题

我发现时间复杂度和空间复杂度非常令人困惑(如果有任何易于理解的博客/视频,请随时提供链接)。

在时间复杂度的情况下,+1是否有影响?或者O(log n)和O(log n + 1)被认为是相同的吗?

英文:

I find time and space complexity very confusing (if there are any easy to understand blogs/videos feel
free to link it).

Does the +1 there make a difference in case of time complexity? or is O(log n) considered the same as O(log n + 1)?

答案1

得分: 2

Additive and multiplicative constants never matter. For all constants M ≠ 0 and A, O(Mf(n) + A) = O(f(n)).

英文:

Additive and multiplicative constants never matter. For all constants M≠0 and A, O(Mf(n) + A) = O(f(n)).

答案2

得分: 0

在计算大O表示法时,常数实际上并不重要,因为我们在计算某物增长的速度,在这里的常数将会在大规模输入时完全无关紧要。

假设有两个排序算法,一个是O(n),另一个是O(n^2),给定输入n=50的情况下。

现在假设我们有一个O(n)的常数为500,另一个O(n^2)的常数为5

O(n) = 50 * 500 = 25000

O(n^2) = 50 * 50 * 5 = 12500

在这种情况下,O(n^2)实际上更快。但是,假设我们有n=1,000,000的情况:

O(n) = 1,000,000 * 500 = 500,000,000

O(n^2) = 1,000,000 * 1,000,000 * 5 = 5,000,000,000,000

所以你可以看到,随着输入变得越来越大,差距会变得越来越大,因此在大O表示法的计算中,常数实际上并不重要。

英文:

When you are calculating the Big O notation, the Constants do not really matter, As we are calculating the speed at which something will grow, Having a constant here will be completely irrelevant with a large input.

Assuming having two algorithms for sorting with O(n) and O(n^2), given an input of n=50

Now assuming that we do have a constant for the O(n) of 500 and another constant for O(n^2) of 5

O(n) = 50 * 500 = 25000

O(n^2) = 50 * 50 * 5 = 12500

for this case, the O(n^2) is actually faster, But assuming we have n = 1,000,000 for example

O(n) = 1,000,000 * 500 = 500,000,000 

O(n^2) = 1,000,000 * 1,000,000 * 5 = 5,000,000,000,000 

So as you can see, as the input gets larger and larger the gap will grow, and therefore the constant does not really matter in the Big O notation calculations.

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  • 本文由 发表于 2023年3月12日 13:30:24
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