究竟是什么大Ө符号重新present？符号、present
我真搞不清楚大O，大欧米茄和大西塔符号之间的差异。
I'm really confused about the differences between big O, big Omega, and big Theta notation.
据我所知，大O是上界，大欧米茄是下限，但究竟是什么大Ө（THETA）重新present？
I understand that big O is the upper bound and big Omega is the lower bound, but what exactly does big Ө (theta) represent?
我已阅读，这意味着 紧约束的，但什么意思？
I have read that it means tight bound, but what does that mean?
推荐答案
这意味着，该算法在给定函数两个大O和大欧米茄。
It means that the algorithm is both big-O and big-Omega in the given function.
例如，如果是Ө（N），则存在常数 K ，这样你功能（运行时间，等等），大于 N *氏/ code>足够大的 N ，和一些其他的常 K 这样，你的功能比 N *氏/ code>足够大的 N 。
For example, if it is Ө(n), then there is some constant K, such that your function (run-time, whatever), is larger than n*K for sufficiently large n, and some other constant k such that your function is smaller than n*k for sufficiently large n.
在换句话说，对于足够大的 N ，它被夹在两个线性函数之间
In other words, for sufficiently large n, it is sandwiched between two linear functions.
