如何搜索并删除字符串列表数组中的所有重复项 [英] How Do I Search And Delete All The Duplicates In A String List Array

问题描述

如何搜索和删除字符串列表数组中的所有重复项



例如： -

how do i search and delete all the duplicates in a string list array

for example:-

List<string> st = new List<string> { "Hello", "World", "Welcome", "To", "Csharp", "Welcome", "World", "Hello", "To", "Hello" }; //Example string array

现在应该删除重复项，剩下的应该保存在新的列表数组中，我也希望新数组中已删除项目的位置



i这样做很简单，但没有使用列表或genric集合

now duplicates should be deleted and remaining should be saved in the new list array and also i want the positions of the deleted items in new array

i did this in easy way but not by using list or genric collections

using System;

namespace testing
{
    class Program
    {
        static void Main(string[] args)
        {
            try
            {
                int i = 0, j = 0, k = 0, n = 0, ctr = 0;

                Console.WriteLine("Please enter how many elements you want to enter..");
                n = int.Parse(Console.ReadLine());

                string[] a = new string[n];
                
                Console.WriteLine("Enter elements ");
                for (i = 0; i < n; i++)
                {
                    a[i] = Console.ReadLine();
                }

                // Here checking of duplicate elements
                for (i = 0; i < n; i++)
                {
                    for (j = i + 1; j < n; j++)
                    {
                        if (a[i] == a[j])
                        {
                            n = n - 1;
                            for (k = j; k < n; k++)
                            {
                                a[k] = a[k + 1];
                            }
                            ctr = 1;
                            j = j - 1;
                        }
                    }
                }


                if (ctr == 0)
                {
                    Console.WriteLine("Array does not contain duplicate elements");
                }
                else
                {
                    Console.WriteLine();
                    Console.WriteLine("After deletion the duplicate elements are :-");
                    for (i = 0; i < n; i++)
                    {
                        Console.WriteLine(a[i]);
                    }
                }
            }
            
            catch (Exception e)
            {
                Console.WriteLine(e.Message);
            }

            Console.Read();
        }
    }
}

请帮助

please help

推荐答案

这与ridoy的解决方案2类似，不同之处在于它保留原始单词顺序，为重复的免费结果生成新列表。 />
时间复杂度也 O（n）。 （除非 st 获得长，否则这不是什么大问题！）

This is similar to Solution 2 by ridoy, except it preserves the original word order generating a new list for duplicate free result.
It is also O(n) in time complexity. (Which isn't a big deal unless st gets long!)

List<string> st = new List<string> { "Hello", "World", "Welcome", "To", "Csharp", "Welcome", "World", "Hello", "To", "Hello" }; //Example string array
HashSet<string> seen = new HashSet<string>();
List<string> duplicateFree = new List<string>();
List<int> deletedIndices = new List<int>();
int ix = 0;
foreach (var s in st)
{
  // seen.Add(s) returns false if s is already in seen
  // so false means this s is a duplicate
  if (seen.Add(s))
  {
    duplicateFree.Add(s);
  }
  else
  {
    deletedIndices.Add(ix);
  }
  ++ix;
}
// duplicateFree is the cleaned-up list:
// { "Hello", "World", "Welcome", "To", "Csharp" }
// If really necessary to be an array:
int[] deletedIndicesArray = deletedIndices.ToArray();

你可以尝试这样的方式：

You can try something like this way:

yourList.Sort();
int index = 0;
List<int> deletedIndex = new List<int>();
while (index < yourList.Count - 1)
{
    if (yourList[index] == yourList[index + 1])
    {
        yourList.RemoveAt(index);
        //index represents the position of deleted items
        deletedIndex.Add(index);
    }
    else
        index++;
}

// You can convert it back to an array if you would like to
int[] deletedIndexArray= deletedIndex.ToArray();

您可以使用Distinct删除重复项，请参阅以下代码

You can use Distinct to remove duplicate, see following code

List<string> st = new List<string> { "Hello", "World", "Welcome", "To", "Csharp", "Welcome", "World", "Hello", "To", "Hello" }; //Example string array
           List<string> lst = st.Distinct().ToList();

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