如何在foreach中合并重复项

using System;
using System.Collections.Generic;

public class Program
{
    public static void Main()
    {
        List<int> numbers = new List<int> { 1, 2, 2, 3, 4, 4, 5 };

        Dictionary<int, int> countDict = new Dictionary<int, int>();

        foreach (int num in numbers)
        {
            if (countDict.ContainsKey(num))
            {
                countDict[num]++;
            }
            else
            {
                countDict[num] = 1;
            }
        }

        List<int> mergedList = new List<int>();

        foreach (KeyValuePair<int, int> pair in countDict)
        {
            if (pair.Value > 1)
            {
                // 合并重复项为一个新的列表
                for (int i = 0; i < pair.Value; i++)
                {
                    mergedList.Add(pair.Key);
                }
            }
            else
            {
                // 保留非重复项
                mergedList.Add(pair.Key);
            }
        }

        Console.WriteLine("合并后的列表：");
        foreach (int num in mergedList)
        {
            Console.WriteLine(num);
        }
    }
}

合并后的列表：
1
2
2
3
4
4
5