public static void Main()
var input1 = new int[] {2,7,11,15};
var result1 = SumOfPair(input1, sum1);
Console.WriteLine("[{0}]", string.Join(", ", result1));
public static int[] SumOfPair(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 };