c#数组案例（较复杂）两个数组合并、去重和取交集

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace _01_数组
{
    internal class Program
    {
        static void Main(string[] args)
        {
            // 1. 合并两个数组
            int[] list1 = { 1, 2, 3 };
            int[] list2 = { 2, 4, 7 };
            int[] arr = Connect(list1, list2);
            Console.WriteLine(Join(arr));

            // 2.数组元素去重
            int[] list3 = { 2, 4, 6, 4, 6, 7, 2, 1, 9 };
            int[] arr1 = Distinct(list3);
            Console.WriteLine(Join(arr1));

            // 3.两个数组的交集
            int[] list4 = { 3, 5, 7, 2, 5, 3 };
            int[] list5 = { 2, 8, 1, 7, 3 };
            int[] arr2 = Intersection(list4, list5);
            Console.WriteLine(Join(arr2));
            Console.ReadLine();
        }

        static string Join(int[] arr, string link = ",")
        {
            string str = "";
            for (int i = 0; i < arr.Length; i++)
            {
                str += arr[i];
                if (i != arr.Length - 1)
                {
                    str += link;
                }
            }
            return str;
        }


        /// <summary>
        /// 将两个数组连接为一个数组
        /// </summary>
        /// <param name="arr1">要链接的第一个数组</param>
        /// <param name="arr2">要连接的第二个数组</param>
        /// <returns>连接后的新数组</returns>
        static int[] Connect(int[] arr1, int[] arr2)
        {
            int[] newArr = new int[arr1.Length + arr2.Length];
            for (int i = 0; i < arr1.Length; i++)
            {
                newArr[i] = arr1[i];
            }
            for (int i = 0; i < arr2.Length; i++)
            {
                newArr[arr1.Length + i] = arr2[i];
            }
            return newArr;
        }

        /// <summary>
        /// 对数组进行去重
        /// </summary>
        /// <param name="arr">需要去重的数组</param>
        /// <returns>去重之后的数组</returns>
        static int[] Distinct(int[] arr)
        {
            // 去重之后的新数组
            int[] newArr = { };
            for (int i = 0; i < arr.Length; i++)
            {
                // 获取当前元素第一次出现的位置   
                int index = FindFirstIndex(arr, arr[i]);

                // 判断元素是否是第一次出现
                if (index == i)
                {
                    newArr = Add(newArr, arr[i]);
                }
            }
            return newArr;
        }


        /// <summary>
        /// 获取两个数组的交集
        /// </summary>
        /// <param name="arr">数组1</param>
        /// <param name="arr2">数组2</param>
        /// <returns>返回交集的数组</returns>
        static int[] Intersection(int[] arr1, int[] arr2)
        {
            int[] MaxArr = arr1.Length > arr2.Length ? arr1 : arr2;
            int[] MinArr = arr1.Length < arr2.Length ? arr1 : arr2;

            // 存储两个数组中的交集
            int[] newArr = { };
            for (int i = 0; i < MinArr.Length; i++)
            {
                // 获取当前元素在大数据中存储的位置
                int index = FindFirstIndex(MaxArr, MinArr[i]);
                // 判断索引是否存在
                if (index != -1)
                {
                    // 如果存在则说明是交集 就存储到新数组中
                    newArr = Add(newArr, MinArr[i]);
                }
            }
            return newArr;
        }
        static int FindFirstIndex(int[] arr, int value)
        {
            int index = -1;// 索引初始值为 -1 表示没有找到相关元素
            for (int i = 0; i < arr.Length; i++)
            {
                if (arr[i] == value)
                {
                    index = i;
                    break;
                }
            }
            return index;
        }
        static int[] Remove(int[] arr, int index)
        {
            if (index >= arr.Length)
            {
                return arr;
            }
            int[] newArr = new int[arr.Length - 1];
            int count = 0;
            for (int i = 0; i < arr.Length; i++)
            {
                if (i != index)
                {
                    newArr[count++] = arr[i];
                }
            }
            return newArr;
        }
        static int[] Add(int[] arr, int item)
        {
            int[] newArr = new int[arr.Length + 1];
            for (int i = 0; i < arr.Length; i++)
            {
                newArr[i] = arr[i];
            }
            newArr[newArr.Length - 1] = item;
            return newArr;
        }

    }
}