Two Sum【LeetCode】

Given an array of integers, return indices of the two numbers such that they add up to a specific target.

You may assume that each input would have exactly one solution, and you may not use the same element twice.

Example:

Given nums = [2, 7, 11, 15], target = 9,

Because nums[0] + nums[1] = 2 + 7 = 9,
return [0, 1].

my soluction:

public class Solution {
    public int[] TwoSum(int[] nums, int target) {
            Dictionary<int, int> dic = new Dictionary<int, int>(); 
            for (int i = 0; i < nums.Length; i++)
            {
                dic.Add(i,nums[i]);
                //dic.Add(nums[i],i);
            }

            for (int i = 0; i < nums.Length; i++)
            {
                int complement = target - nums[i];
                if (dic.ContainsValue(complement))
                {
                    var keys=dic.Where(m=>m.Value==complement).Select(m=>m.Key);
                    foreach(var item in keys)
                    {
                        if(item != i)
                        {
                            return new int[]{i,item};
                        }
                    }
                    
                }
            }
            throw new Exception("none");
    }
}