查找之索引查找

c代码：

// SearchTest.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"
#include "stdio.h"
#include "stdlib.h"

#define N 10
#define MAX -1

typedef struct dic{
    int max_number;
    int begin,end;
}dic;
dic list[N];

//索引表创建--6为分割点,这个并没有按照每块的最大值顺序排列
int devide(int digit[],int n)
{
    int i=1,k,j=1,temp = n;
    int max;
    while(n>0)
    {
        k = i+5;
        printf("k="+k);printf("
");
        max = MAX;
        if(n<6)
        {
            printf("n<6执行");printf("
");
            list[j].begin = i;
            printf("begin="+list[j].begin);printf("
");
            for(;i<=temp;i++)
            {
                if(digit[i]>max) 
                    max = digit[i];
            }
            list[j].end = temp;
            printf("end ="+list[j].end);printf("
");
        }
        else
        {
            printf("n>=6执行");printf("
");
            list[j].begin = i;
            printf("begin="+list[j].begin);printf("
");
            for(;i<=k;i++)
            {
                if(digit[i]>max)
                    max = digit[i];
            }
            list[j].end = k;
            printf("end ="+list[j].end);printf("
");
        }

        list[j].max_number = max;
        printf("j="+j);printf("
");
        j++;
        printf("n="+n);printf("
");
        n-=6;
        
    }
    return j-1;
}

int Search(int *digit,int k,int count)
{
    int i,pos;
    for(i=1;i<=count;i++)
    {
        if(list[i].max_number == k) return list[i].begin;
        if(list[i].max_number > k) break;//由此看来每块的最大值确实是从小到大排列过的，但是前面哪里排过呢
    }
    for(pos = list[i].begin ;pos<=list[i].end;pos++)
    {
        if(digit[pos]==k) return pos;
    }
    return -1;
}



int _tmain(int argc, _TCHAR* argv[])
{
    int *digit;
    int pos,n,k,count;
    n=10;
    digit = (int *)malloc(sizeof(int)*(n+1));
    digit[0] = 1;
    digit[1] =2;
    digit[2] = 2;
    digit[3]= 4;
    digit[5] = 5;
    digit[6] = 6;
    digit[7] = 7;
    digit[8] = 8;
    digit[9] = 9;
    count = devide(digit,n);
    k = 4;
    if((pos = Search(digit,k,count))!=-1)
        printf("the position of the number is %d
",pos);
    else 
        printf("the number you want to search does not exist.
");
    return 0;
}

虽然可以正确查找，但是试图通过打印控制台分析执行步骤却不方便，还是用自己比较熟悉的java写一遍吧

java代码：

package sjjg;

public class Dic {

    int max_number;
    int begin;
    int end;
    public int getMax_number() {
        return max_number;
    }
    public void setMax_number(int max_number) {
        this.max_number = max_number;
    }
    public int getBegin() {
        return begin;
    }
    public void setBegin(int begin) {
        this.begin = begin;
    }
    public int getEnd() {
        return end;
    }
    public void setEnd(int end) {
        this.end = end;
    }
    
    
}

以上是实体类，也就是c中的结构体，下面是算法：

package sjjg;

import java.util.ArrayList;
import java.util.List;

public class SearchTest {
    static List<Dic> list = new ArrayList<Dic>();
    
    public List<Dic> getList() {
        return list;
    }

    public void setList(List<Dic> list) {
        this.list = list;
    }
    
    static{
        for(int i=0;i<10;i++){
            Dic d = new Dic();
            list.add(d);
        }
    }

    static int devide(int[] digit,int n){
        int i=0,k,j=0,temp = n-1;
        int max;
        
        while(n>0){
            k=i+5;
            System.out.println("k="+k);
            max = -1;
            if(n<6){
                System.out.println("n<6--");
                list.get(j).begin = i;
                System.out.println("begin="+i);
                for(;i<=temp;i++){
                    if(digit[i]>max) max = digit[i];
                }
                list.get(j).end = temp;
                System.out.println("end="+temp);
            }else{
                System.out.println("n>6--");
                list.get(j).begin = i;
                System.out.println("begin="+i);
                for(;i<=k;i++){
                    if(digit[i]>max) max = digit[i];
                }
                list.get(j).end = k;
                System.out.println("end="+k);
            }
            
            list.get(j).max_number = max;
            j++;
            n-=6;
        }
        return j;
    }
    
    static int search(int[] digit,int k,int count){
        System.out.println("search--");
        int i,pos;
        for(i=0;i<count;i++){
            if(list.get(i).max_number == k){
                System.out.println("list.get(i).max_number == k");
                return list.get(i).begin;
            }
            if(list.get(i).max_number >k){
                System.out.println("list.get(i).max_number >k");
                break;
            }
            System.out.println("循环次数i="+i);
        }
        System.out.println("begin to for(pos = list.get(i).begin;pos<=list.get(i).end;pos++)");
        for(pos = list.get(i).begin;pos<=list.get(i).end;pos++){
            System.out.println("pos="+pos+"digit[pos]="+digit[pos]);
            if(digit[pos] == k) return pos;
        }
        return -1;
    }
    
    
    
    public static void main(String[] args) {
        int digit[] = new int[10];
        digit[0] = 1;
        digit[1] =2;
        digit[2] = 2;
        digit[3]= 4;
        digit[5] = 5;
        digit[6] = 6;
        digit[7] = 7;
        digit[8] = 8;
        digit[9] = 9;
        int pos,n,k,count;
        n=10;
        count = devide(digit,n);
        System.out.println("count="+count);
        k = 4;
        if((pos = search(digit,k,count))!=-1){
            System.out.println("pos="+pos);
        }else{
            System.out.println("not exit");
        }
        
    }
}

索引查找是在简单查找的基础上分块，所以又叫分块查找。

未解决的问题：怎么将每个块按照最大值的大小顺序排列，具体的算法分析，等以后会补上。