```
public int[] TwoSum(int[] nums, int target)
{
int[] RetIndecis = {0,0};
Hashtable hsNums = new Hashtable();
hsNums.Clear();
//i is the latter index
for(int i=0;i<nums.Length;i++)
{
int targetKey = target - nums[i];
//if targetKey exist
if(hsNums.ContainsKey(targetKey))
{
RetIndecis[1] = i + 1;
RetIndecis[0] = (int)hsNums[targetKey];
return RetIndecis;
}
//key is the number and value is the index,filter the number which has existed
if(!hsNums.ContainsKey(nums[i]))
hsNums.Add(nums[i],i + 1);
}
return(RetIndecis);
}
```