Two Sum via C#

Problem: Given an array of integers, find two numbers such that they add up to a specific target number.

Answer via C# using HashTable:

 public class Solution {  
   public int[] TwoSum(int[] nums, int target) {  
     List<int> arr = new List<int>();  
     Hashtable hashTable = new Hashtable();  
     for (int i = 0; i < nums.Length;i++)  
     {  
       hashTable[nums[i]] = i;  
     }  
       
     for (int i = 0; i < nums.Length; i++)  
     {  
       // get key2, index2  
       var key2 = target - nums[i];  
       if (hashTable.Contains(key2) && ((Int32)hashTable[key2] != i) && ((Int32)hashTable[key2] > i))  
       {  
         int i2 = (Int32)hashTable[key2];  
         arr.Add(i + 1);  
         arr.Add(i2 + 1);  
       }  
     }  
       
     return arr.ToArray();  
   }  
 }  

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