嘿,伙计们,我正在从Dasgupta的算法书中解决一些大问题,并且被困在一些问题上。
1) f(n) =n^0.1g(N)= (log )^10
根据Asymptotic Complexity of Logarithms and Powers上的最高答案,“对于任何正数a,b,log(N)^a总是O(n^b)。”所以对于1),f= omega(g)
2) f(n) =n^1.01g(N)=nlog^2n我猜f= omega(g)。这个例子是正确的还是不同的情况,因为log是平方并乘以n?
请说明您为解决这类问题而采取的步骤
发布于 2013-08-22 01:38:08
你对第一个问题的回答是正确的,你对该规则的应用也是正确的。这里有一个证明,对于任何a>0,log(n) = O(n^a) (显然与上述规则等价):
The derivative of n^a is a*(n^(a-1))
The derivative of log(n) = 1/n
Therefore, for large enough n, the derivative of n^a is more than the derivative of log(n)
Therefore, for large enough n, n^a > log(n)
Therefore log(n) = O(n^a)你对第二个问题的回答是正确的。这是一个证据:
g(n) = O(f(n)) if and only if log(log(n)) = O(n^0.01)
log(log(n)) = O(log(n)) so log(log(n)) = O(O(n^0.01)) = O(n^0.01)https://stackoverflow.com/questions/15909068
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