我读过有关算法的运行时间在某些算法的书，它是pssed作为前$ P $ O（N）。对于例如，给定code将运行在O为最好的情况和安培（n）的时间;为O（n 3 ）为最坏的情况。这是什么意思＆安培;一个人如何计算它自己的code？是不是像线性时间，并且是像每个predefined库函数都有自己的运行时，应牢记调用它之前？谢谢...

I've read about algorithm run-time in some algorithm books, where it's expressed as, O(n). For eg., the given code would run in O(n) time for the best case & O(n3) for the worst case. What does it mean & how does one calculate it for their own code? Is it like linear time , and is it like each predefined library function has their own run-time which should be kept in mind before calling it? Thanks...

推荐答案

一个初学者指南大O符号可能是一个良好的开端：

A Beginner's Guide to Big O Notation might be a good place to start:

的http：//抢铃.NET / 2009/06 / A-新手引导到大O记法/

也看看维基百科

http://en.wikipedia.org/wiki/Big_O_notation

有计算器上的几个相关问题，并很好的答案

there are several related questions and good answers on stackoverflow

纯英文解释，大澳

和

大O的八岁儿童？