C#面试题伪代码

收集了几个常见的要求写伪代码的面试题:

 class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Hello World!");
            DoBubbleSorting();
            Calc(6);
            CalcFibonacciSequence(8);
            DoIsPower();
            TestStringLength();
            TestStruct();
        }


        /// <summary>
        /// 面试题1、冒泡排序
        /// </summary>
        public static void DoBubbleSorting()
        {
            int[] array = {3, 1, 9, 5, 6, 7};
            
            Console.WriteLine("排序前数字：");
            Console.WriteLine(string.Join(",", array));
            for (int i = 0; i < array.Length; i++)
            {
                for (int j = i + 1; j < array.Length; j++)
                {
                    if (array[i] > array[j])
                    {
                        int tmp = array[j];
                        array[j] = array[i];
                        array[i] = tmp;
                    }
                }
            }
            Console.WriteLine("排序后数字：");
            Console.WriteLine(string.Join(",",array));
        }

        /// <summary>
        /// 面试题2、求以下表达式的值，写出您想到的一种或几种实现方法：1-2+3-4+……+m
        /// </summary>
        public static void Calc(int count)
        {
            Console.WriteLine("求以下表达式的值，写出您想到的一种或几种实现方法：1-2+3-4+……+m");
            int num = 0;
            for (int i = 1; i <= count; i++)
            {
                if (i % 2==1)
                {
                    num += i;
                }
                else
                {
                    num -= i;
                }
            }
            Console.WriteLine($"{count}个数值为："+num);
        }

        /// <summary>
        /// 面试题3、一列数的规则如下: 1、1、2、3、5、8、13、21、34...... 求第30位数是多少，用递归算法实现
        /// </summary>
        public static void CalcFibonacciSequence(int num) 
        {
            Console.WriteLine("一列数的规则如下: 1、1、2、3、5、8、13、21、34...... 求第30位数是多少，用递归算法实现");
            Console.WriteLine($"第{num}个数是："+Fibonacci(num));
        }

        static int Fibonacci(int num)
        {
            if (num > 0 && num <= 2)
            {
                return 1;
            }
            else
            {
                return Fibonacci(num - 1) + Fibonacci(num - 2);
            }
        }

        public static void DoIsPower()
        {
            Console.WriteLine("现有一个整数number，请写一个方法判断这个整数是否是2的N次方,以4(100)    7(0111)    8(1000)为例");

            Console.WriteLine("4 & 3 --> 100 & 011     = 0");
            Console.WriteLine("7 & 6 --> 0111 & 0110  != 0");
            Console.WriteLine("8 & 7 --> 1000 & 0111   = 0");

            Console.WriteLine(GetFlag(5)?"":"5不是2的N次方");
            Console.WriteLine(GetFlag(16) ? "16是2的N次方" : "");
        }

        public static bool GetFlag(int num)
        {
            return (num > 0) && (num & num - 1) == 0;
        }

        /// <summary>
        /// 面试题5
        /// </summary>
        public static void TestStringLength()
        {
            string strTmp = "abcdefg某某某";
            Console.WriteLine($"{strTmp}的二进制长度和字符串长度各是多少？");
            Encoding.RegisterProvider(CodePagesEncodingProvider.Instance);
            //int i = System.Text.Encoding.GetEncoding("gb2312").GetBytes(strTmp).Length;
            int i = System.Text.Encoding.Default.GetBytes(strTmp).Length;//卧槽，这里有坑，默认字符集utf8的话汉字是2-4个字节，这里是16个，gb2312的话，应该是13个吧
            int j = strTmp.Length;
            Console.WriteLine($"二进制长度{i},字符串长度{j}");
        }

        /// <summary>
        /// 面试题6
        /// </summary>
        public static void TestStruct()
        {
            var obj=new MyStruct(100,100);
            var obj2 = obj;
            obj2.X = 200;
            Console.WriteLine($"obj.X->{obj.X},obj.Y->{obj.Y};obj2.X->{obj2.X},obj2.Y->{obj2.Y}");
        }
    }

    /// <summary>
    /// 面试题4、请写出C#中的单例模式
    /// </summary>
    public class Single
    {
        private static Single instance;
        private Single() { }
        public static Single GetInstance()
        {
            if (instance == null)
            {
                instance = new Single();
            }
            return instance;
        }
    }


    public struct MyStruct
    {
        public MyStruct(int x, int y)
        {
            X = x;
            Y = y;
        }

        public int X { get; set; }
         public int Y { get; set; }


    }