Prospective patients must be fit for travel, the cost must make economic sense, the length of stay should be relatively short and follow-up care must be predictable and fairly brief.

VOA: standard.2010.04.08

Because if you did what I suggested with the list, the time to look up the key would be linear in the length of the list. You'd have to look at each element until you found the key.

字典是用一种很神奇的，叫做散列法的算法,来实现的，后面我们将,会学到一点关于。

麻省理工公开课 - 计算机科学及编程导论课程节选