索引查找Java实现

package 索引查找;

import java.util.Scanner;

public class IndexSearch {

public static long stu[] = {
1080101,1080102,1080103,1080104,1080105,1080106,0,0,0,0,
1080201,1080202,1080203,1080204,0,0,0,0,0,0,
1080301,1080302,1080303,1080304,0,0,0,0,0,0
};

static Item[]indexTable = {
new Item(10801,0,6),
new Item(10802,10,4),
new Item(10803,20,4)
};

public static int indexSearch(int key){
int i,index1,start = 0,length = 0;
index1 = key/100;
for (i = 0;i<indexTable.length;i++) {
if (indexTable[i].index == index1) {
start = indexTable[i].start;
length = indexTable[i].length;
break;
}
}
if (i >= indexTable.length) {
return -1;
}
for (i = start;i<start+length;i++) {
if (stu[i] == key) {
return i;
}
}
return -1;
}

//向主表中插入元素，从stu这个数组中我们可以看出来里面有0的值，这些值就是预留的空间
/**
* 我们只需要把这些0的值替换掉就行了，值涉及到了索引表和相应的字表，而不是整个表
* 所以比较和移动的效率比较高
*/

public static int insertNode(int key){
int i,index1,start = 0,length = 0;
index1 = key/100;
for (i = 0;i<indexTable.length;i++) {
if (indexTable[i].index == index1) {
start = indexTable[i].start;
length = indexTable[i].length;
break;
}
}
if (i >= indexTable.length) {
return -1;
}

//保存关键字到主表中
stu[start+length] = key;
indexTable[i].length++;
return 0;
}

public static void main(String[] args) {
Scanner input = new Scanner(System.in);

System.out.println("原始数据：");
for (int i = 0;i<stu.length;i++) {
System.out.print(stu[i]+" ");
}
System.out.println();
//		System.out.println("输入查找的关键字");
//		int key = input.nextInt();
//		int pos = indexSearch(key);
//		if (pos >= 0) {
//			System.out.printf("查找成功，该关键字位于数组的第%d个位置\n",pos);
//		}else{
//			System.out.println("查找失败！");
//		}

System.out.println("输入插入的关键字");
int num = input.nextInt();
if (insertNode(num) == -1) {
System.out.println("插入失败！");
}else {
for (int i = 0;i<stu.length;i++) {
System.out.print(stu[i]+" ");
}
System.out.println();
}

}

}

package 索引查找; import java.util.Scanner; public class IndexSearch { public static long stu[] = { 1080101,1080102,1080103,1080104,1080105,1080106,0,0,0,0, 1080201,1080202,1080203,1080204,0,0,0,0,0,0, 1080301,1080302,1080303,1080304,0,0,0,0,0,0 }; static Item[]indexTable = { new Item(10801,0,6), new Item(10802,10,4), new Item(10803,20,4) }; public static int indexSearch(int key){ int i,index1,start = 0,length = 0; index1 = key/100; for (i = 0;i<indexTable.length;i++) { if (indexTable[i].index == index1) { start = indexTable[i].start; length = indexTable[i].length; break; } } if (i >= indexTable.length) { return -1; } for (i = start;i<start+length;i++) { if (stu[i] == key) { return i; } } return -1; } public static void main(String[] args) { Scanner input = new Scanner(System.in); System.out.println("原始数据："); for (int i = 0;i<stu.length;i++) { System.out.print(stu[i]+" "); } System.out.println(); System.out.println("输入查找的关键字"); int key = input.nextInt(); int pos = indexSearch(key); if (pos >= 0) { System.out.printf("查找成功，该关键字位于数组的第%d个位置\n",pos); }else{ System.out.println("查找失败！"); } } }