{
        Console.WriteLine("計算SUM");
        int[] array = new int[] { 2, 7, 11, 15 };
        int target = 9;
        int[] answer = new int[2];

        // 外層迴圈
        for (int i = 0; i < array.Length; i++)
        {
            // 內層迴圈從 i+1 開始，避免重複檢查自己
            for (int j = i + 1; j < array.Length; j++)
            {
                // 檢查兩個數字是否和等於 target
                if (array[i] + array[j] == target)
                {
                    answer[0] = i;
                    answer[1] = j;
                    break;  // 找到結果後可以跳出內層迴圈
                }
            }
        }

        // 輸出結果
        Console.WriteLine($"Input: nums = [{string.Join(", ", array)}], target = {target}\\\\r\\\\nOutput: [{string.Join(", ", answer)}]\\\\r\\\\nExplanation: Because nums[{answer[0]}] + nums[{answer[1]}] == {target}, we return [{string.Join(", ", answer)}].");
    }

兩個和 - LeetCode --- Two Sum - LeetCode