从列表中选择＆LT N个随机元素; T＆GT;在C＃中 [英] Select N random elements from a List<T> in C#

问题描述

我需要一个快速的算法来选择一个通用的清单5随机元素。例如，我想从得到5个随机元素的列表与LT;字符串方式＆gt;

I need a quick algorithm to select 5 random elements from a generic list. For example, I'd like to get 5 random elements from a List<string>.

推荐答案

遍历，并为每个元素进行选择的概率=（需要数/数​​左）

Iterate through and for each element make the probability of selection = (number needed)/(number left)

所以，如果你有40个项目，首先将有机会5/40被选中的。如果是，下一个具有4/39机会，否则它有一个5/39机会。到时候你到了最后，你将有你的5个项目，往往你必须所有的人都在那之前。

So if you had 40 items, the first would have a 5/40 chance of being selected. If it is, the next has a 4/39 chance, otherwise it has a 5/39 chance. By the time you get to the end you will have your 5 items, and often you'll have all of them before that.

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