查找字符串中出现次数最多的字符? [英] Find character with most occurrences in string?

问题描述

例如，我有一个字符串:

For example, I have a string:

"abbbbccd"

b出现次数最多.使用C ++时，处理此问题的最简单方法是将每个字符插入map<>中.我必须在C#中做同样的事情吗?有没有一种使用LINQ做到这一点的优雅方法?

b has the most occurrences. When using C++, the easiest way to handle this is inserting each character into a map<>. Do I have to do the same thing in C#? Is there an elegant way to do it using LINQ?

推荐答案

input.GroupBy(x => x).OrderByDescending(x => x.Count()).First().Key

注意:

• 如果您需要此代码才能在.Net的古代(2.0)版本上工作，请考虑 LinqBridge .如果您不能使用C#3.0(以.Net 2.0为目标)，则可能会缺少lambda支持，因此最好使用其他解决方案. xanatos答案涵盖了另一个.Net 2.0+选项.
• 对于"aaaabbbb"而言，将仅返回其中之一(感谢 xanatos 进行评论).如果您需要所有具有最大数量的元素，请使用 Albin解决方案.
• 由于对此解决方案进行了排序(如果为O(n log n)解决方案).如果您需要的更好-通过线性搜索找到最大值，而不是先排序即可得到O(n).参见 LINQ:如何对集合中所有对象的属性执行.Max()并返回具有最大值的对象

• if you need this to work on ancient (2.0) versions of .Net consider LinqBridge. If you can't use C# 3.0 (targeting .Net 2.0) you probably better off with other solutions due to missing lambda support. Another .Net 2.0+ option is covered in xanatos answer.
• for the case of "aaaabbbb" only one of those will be returned (thanks xanatos for comment). If you need all of the elements with maximum count, use Albin's solution instead.
• due to sorting this if O(n log n) solution. If you need better than that - find Max value by linear search instead of sorting first which will give O(n). See LINQ: How to perform .Max() on a property of all objects in a collection and return the object with maximum value

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