索引查找——算法系列

索引查找

其实这个算法没有怎么理解了。

上代码：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
//哈希查找程序
namespace Test
{
    class Program
    {
        //索引实体
        class IndexItem
        {
            public int index;
            public int start;
            public int length;
        }

        static void Main(string[] args)
        {
            Console.WriteLine("原始数据为：" + string.Join(",", students));
            int value = 205;
            Console.WriteLine("\n插入数据" + value);
            var index = insert(value);
            if (index == 1)
            {
                Console.WriteLine("\n插入后数据: " + string.Join(",", students));
                Console.WriteLine("\n插入元素：205在数组中的位置为：{0}", indexSearch(205) + "位");
            }
            Console.ReadLine();
        }

        static int[] students = {
                                    101,102,103,104,105,0,0,0,0,0,
                                    201,202,203,204,0,0,0,0,0,
                                    301,302,303,0,0,0,0,0,0
                                };

        static IndexItem[] indexItem = {
                                           new IndexItem(){index=1,start=0,length=5},
                                           new IndexItem(){index=2,start=10,length=4},
                                           new IndexItem(){index=3,start=20,length=3}
                                       };

        public static int insert(int key)
        {
            IndexItem item = null;
            var index = key / 100;
            int i = 0;
            for (i = 0; i < indexItem.Count(); i++)
            {
                if (indexItem[i].index == index)
                {
                    item = new IndexItem()
                    {
                        start = indexItem[i].start,
                        length = indexItem[i].length
                    };
                    break;
                }
            }
            if (item == null)
                return -1;
            students[item.start + item.length] = key;
            indexItem[i].length++;
            return 1;
        }

        public static int indexSearch(int key)
        {
            IndexItem item = null;
            var index = key / 100;
            for (int i = 0; i < indexItem.Count(); i++)
            {
                if (indexItem[i].index == index)
                {
                    item = new IndexItem()
                    {
                        start = indexItem[i].start,
                        length = indexItem[i].length
                    };
                    break;
                }
            }

            if (item == null)
                return -1;
            for (int i = item.start; i < item.start + item.length; i++)
            {
                if (students[i] == key)
                    return i;
            }
            return -1;
        }

    }
}