Sequence table
The sequence table is a linear structure in which a section of storage units with continuous physical addresses store data elements in sequence . Generally, array storage is used . Complete data addition, deletion, checking and modification on the array.
The sequence table can generally be divided into:
- Static sequence table: use fixed-length array storage.
- Dynamic sequence table: use dynamically developed array storage.
The static sequence table is suitable for scenarios where you know how much data you need to store.
The fixed-length array of the static sequence table causes N to be large, the space is too much wasted, and the space is not enough. In contrast, the dynamic sequence table is more flexible, and the space is dynamically allocated according to needs.
import java.util.Arrays;
/**
* Created with IntelliJ IDEA.
* Description:手撕顺序表
* User: starry
* Date: 2021 -02 -10
* Time: 9:45
*/
public class MyArrayList {
private int[] elem; //数组
private int usedsize; //有效数据个数
public MyArrayList() {
this.elem = new int[5];
}
public MyArrayList(int capacity) {
this.elem = new int[capacity];
}
// 打印顺序表
public void display() {
for(int i = 0; i < usedsize; i++) {
System.out.print(elem[i] + " ");
}
System.out.println();
}
//判断顺序表是否为满
public boolean isFull() {
return usedsize == elem.length;
}
//判断pos位置是否合法
public boolean isPos(int pos) {
if(pos < 0 || pos > usedsize) {
return false;
}
return true;
}
//二倍扩容
public void resize() {
elem = Arrays.copyOf(elem,elem.length*2);
}
// 在 pos 位置新增元素
public void add(int pos, int data) {
if(isFull()) {
System.out.println("顺序表满了，自动为您扩容");
resize();
}
if(isPos(pos)) {
for(int i = usedsize; i > pos; i--) {
elem[i] = elem[i-1];
}
elem[pos] = data;
usedsize++;
}else {
System.out.println("pos位置不合法");
}
}
//默认插入到最后一个元素那里
public void addLast(int data) {
if (isFull()) {
System.out.println("顺序表满了，自动为您扩容");
resize();
}
elem[usedsize] = data;
usedsize++;
}
// 判定是否包含某个元素
public boolean contains(int toFind) {
for(int i = 0; i < usedsize; i++) {
if(elem[i] == toFind) {
return true;
}
}
return false;
}
// 查找某个元素对应的位置
public int search(int toFind) {
for(int i = 0; i < usedsize; i++) {
if(elem[i] == toFind) {
return i;
}
}
return -1;
}
// 获取 pos 位置的元素
public int getPos(int pos) {
if(isPos(pos)) {
return elem[pos];
}
return -1;
}
// 给 pos 位置的元素设为 value
public void setPos(int pos, int value) {
if(isPos(pos)) {
elem[pos] = value;
}
}
//删除第一次出现的关键字key
public void remove(int toRemove) {
int index = search(toRemove);
if (index == -1) {
System.out.println("没有你想要删的数据");
return;
}
for (int j = index; j < usedsize-1; j++) {
elem[j] = elem[j+1];
}
usedsize--;
}
// 获取顺序表长度
public int size() {
return usedsize;
}
// 清空顺序表
public void clear() {
usedsize = 0;
}
public static void main(String[] args) {
MyArrayList myArrayList = new MyArrayList();
myArrayList.add(0,1);
myArrayList.add(1,2);
myArrayList.add(2,3);
myArrayList.add(3,4);
myArrayList.add(4,5);
myArrayList.display();
System.out.println("=======================");
myArrayList.addLast(6);
myArrayList.display();
System.out.println("=======================");
System.out.println(myArrayList.contains(3));
System.out.println(myArrayList.contains(10));
System.out.println("=======================");
System.out.println(myArrayList.search(3));
System.out.println(myArrayList.search(10));
System.out.println("=======================");
System.out.println(myArrayList.getPos(3));
System.out.println(myArrayList.getPos(7));
System.out.println("=======================");
myArrayList.setPos(0,11);
myArrayList.display();
System.out.println("=======================");
myArrayList.remove(11);
myArrayList.display();
myArrayList.remove(22);
System.out.println("=======================");
System.out.println(myArrayList.size());
System.out.println("=======================");
myArrayList.clear();
System.out.println(myArrayList.size());
}
}