using System;
namespace Lesson7
{
    class Program
    {
        static int Compare(int a, int b)
        {
            int max = (a > b) ? a : b;
            return max;
        }

        static float[] Circle(float r)
        {
            float pi = 3.14f;
            float perimeter = 2 * pi * r;
            float area = pi * (r * r);
            return new float[] { perimeter, area };
        }
        static int[] ComplexCompare(int[] a)
        {
            int sum = 0, min = a[0],max = a[0],avg=0;
            for (int i = 0; i < a.Length; i++)
            {
                sum += a[i];
                if (a[i] > max)
                {
                    max = a[i];
                }
                if (a[i] < min)
                {
                    min = a[i];
                }
            }
            avg = sum / a.Length;
            return new int[] { sum, max, min, avg };
        }
        static bool Primenumber(int a)
        {
            for (int i = 2; i < a; i++)
            {
                if (a % i == 0)
                    return false;
            }
            return true;
        }
        static bool Year(int a)
        {
            if (a%400 == 0 || (a%4 == 0 && a%100 != 0))
            {
                return true;
            }
            return false;
        }
        static void Main(string[] arg)
        {
            Console.WriteLine("比较大小：");
            Console.WriteLine(Compare(10, 20));

            Console.WriteLine("圆：");
            float[] circle = Circle(20);
            Console.WriteLine("perimeter:" + circle[0] + " " + "area:" + circle[1]);

            Console.WriteLine("综合：");
            int[] x = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
            int[] result = ComplexCompare(x);
            Console.WriteLine("总和：" + result[0] + "最大" + result[1] + "最小" + result[2] + "平均" + result[3]);

            bool result2 = Primenumber(21);
            if (result2)
            {
                Console.WriteLine("是质数");
            }
            else
            {
                Console.WriteLine("不是质数");
            }

            Console.WriteLine("闰年：");
            Console.WriteLine(Year(2200));


            
        }
    }
}