twoSum.cs

public class Solution {
    public int[] TwoSum(int[] nums, int target) {
    for (int i = 0; i < nums.Length; i++) {
        for (int j = i + 1; j < nums.Length; j++) {
            if (nums[j] == target - nums[i]) {
                return new int[] { i, j };
                }
            }
        }
        return new int[0];
    }
}