//第一版參考解答
using System;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {

            int [] s={1,2,3,4,5,6,7,8,9,10};

            for (int i = 0; i < 10; i++)
            {
                Console.Write(s[i]+" ");
            }

            double avg = Mean(s);

            Console.Write("\n");
            Console.WriteLine("mean = {0}", avg);

        }

        static double Mean(int[] x) //輸入一個陣列，回傳平均值
        {
            double mean = 0;
            for (int i = 0; i < x.Length; i++)
            {
                mean += x[i];
            }

            mean /= x.Length;

            return mean;
        }


 
    }
}



//第二版參考解答
using System;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {

            int [] s={1,2,3,4,5,6,7,8,9,10};

            for (int i = 0; i < 10; i++)
            {
                Console.Write(s[i]+" ");
            }

            double avg = Mean(s);
            double sqa = MeanSquare(s);

            Console.Write("\n");
            Console.WriteLine("mean = {0},\tmean square = {1}", avg, sqa);

        }

        static double Mean(int[] x) //輸入一個陣列，回傳平均值
        {
            double mean = 0;
            for (int i = 0; i < x.Length; i++)
            {
                mean += x[i];
            }

            mean /= x.Length;

            return mean;
        }

        static double MeanSquare(int[] x) //輸入一個陣列，回傳平方的平均
        {
            double meanSquare = 0;
            for (int i = 0; i < x.Length; i++)
            {
                meanSquare += Math.Pow(x[i], 2);
            }
            meanSquare /= x.Length;
            return meanSquare;
        }

 
    }
}


//第三版參考解答
using System;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {

            int [] s={1,2,3,4,5,6,7,8,9,10};

            for (int i = 0; i < 10; i++)
            {
                Console.Write(s[i]+" ");
            }

            double avg = Mean(s);
            double sqa = MeanSquare(s);
            double std = StdDev(s);

            Console.Write("\n");
            Console.WriteLine("mean = {0},\tmean square = {1},\tstd = {2}", avg, sqa, std);

        }

        static double Mean(int[] x) //輸入一個陣列，回傳平均值
        {
            double mean = 0;
            for (int i = 0; i < x.Length; i++)
            {
                mean += x[i];
            }

            mean /= x.Length;

            return mean;
        }

        static double MeanSquare(int[] x) //輸入一個陣列，回傳平方的平均
        {
            double meanSquare = 0;
            for (int i = 0; i < x.Length; i++)
            {
                meanSquare += Math.Pow(x[i], 2);
            }
            meanSquare /= x.Length;
            return meanSquare;
        }

        static double StdDev(int[] x) //輸入一個陣列，回傳標準差
        {
            double std = 0;
            double meanSquare = 0;
            double mean = 0;
            meanSquare = MeanSquare(x); //呼叫MeanSquare()函式來計算數列平方的平均值
            mean = Mean(x); //呼叫Mean()函式來計算數列的平均值
            std = Math.Sqrt(meanSquare - Math.Pow(mean, 2));
            return std;
        }
    }
}


//第四版參考解答
using System;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {

            Random rand = new Random();
            int k;
            int length = 100;
            int[] number = new int[length];

            for (int i = 0; i < length; i++)
            {
                k = rand.Next() % 50 + 1; //產生1~50之間的亂數
                number[i] = k;
                Console.Write(k + " ");
            }


            double avg = Mean(number);
            double sqa = MeanSquare(number);
            double std = StdDev(number);

            Console.Write("\n");
            Console.WriteLine("mean = {0},\tmean square. = {1},\tStd = {2}", avg, sqa, std);

        }

        static double Mean(int[] x) //輸入一個陣列，回傳平均值
        {
            double mean = 0;
            for (int i = 0; i < x.Length; i++)
            {
                mean += x[i];
            }

            mean /= x.Length;

            return mean;
        }

        static double MeanSquare(int[] x) //輸入一個陣列，回傳平方的平均
        {
            double meanSquare = 0;
            for (int i = 0; i < x.Length; i++)
            {
                meanSquare += Math.Pow(x[i], 2);
            }
            meanSquare /= x.Length;
            return meanSquare;
        }

        static double StdDev(int[] x) //輸入一個陣列，回傳標準差
        {
            double std = 0;
            double meanSquare = 0;
            double mean = 0;
            meanSquare = MeanSquare(x); //呼叫MeanSquare()函式來計算數列平方的平均值
            mean = Mean(x); //呼叫Mean()函式來計算數列的平均值
            std = Math.Sqrt(meanSquare - Math.Pow(mean, 2));
            return std;
        }
    }
}

}