30秒学会 C# 片段 – MostFrequent

Returns the most frequent element of a collection.

Use IEnumerable.GroupBy() to group values by value.
Use IEnumerable.OrderByDescending() in combination with IEnumerable.Count() to order the results in descending order based on frequency.
Use IEnumerable.First() to get the first element and return its Key property, which corresponds to the element’s value.

代码实现

using System.Collections.Generic;
using System.Linq;

public static partial class _30s 
{
  public static T MostFrequent<T>(IEnumerable<T> values)
  {
    return values
      .GroupBy(v => v)
      .OrderByDescending(v => v.Count())
      .First()
      .Key;
  }
}

使用样例

int[] nums = { 1, 2, 3, 3, 2, 3 };
List<string> str = new List<string> { "a", "b", "b", "c" };

_30s.MostFrequent(nums); // 3
_30s.MostFrequent(str); // "b"