（二）Java数组的使用

Java数组

　　无序数组插入删除查询操作：

public class ArrayList {

    private static int[] intArray;
    private int nElems;
    public ArrayList(int max){
        intArray=new int[max];
        nElems=0;
    }
    
    public boolean find(long searchKey){
        int j;
        for(j=0;j<nElems;j++){
            if(intArray[j]==searchKey){
                break;
            }
        }
        if(j==nElems){
            return false;
        }else{
            return true;
        }
    }
    
    public void insert(int value){
        intArray[nElems]=value;
        nElems++;
    }
    
    public boolean delete(int value){
        int j;
        for(j=0;j<nElems;j++){
            if(value==intArray[j]){
                break;
            }
        }
        if(j==nElems){
            return false;
        }else{
            for(int k=j;k<nElems;k++){
                intArray[k]=intArray[k+1];
            }
            nElems--;
            return true;
        }
    }
    
    public void display(){
        for(int j=0;j<nElems;j++){
            System.out.print(intArray[j]+" ");
        }
        System.out.println();
    }
    
    public static void main(String[] args) {
        int maxSize=100;
        ArrayList arr=new ArrayList(maxSize);
        
        arr.insert(77);
        arr.insert(99);
        arr.insert(44);
        arr.insert(55);
        arr.insert(22);
        arr.insert(88);
        arr.insert(11);
        arr.insert(00);
        arr.insert(66);
        arr.insert(33);
        
        arr.display();
        
        int searchKey=11;
        if(arr.find(searchKey)){
            System.out.println("found "+searchKey);
        }else{
            System.out.println("can't found "+searchKey);
        }
    
        arr.delete(55);
        arr.display();
    }
}

　　二分查找，按序插入

//线性查找，二分查找
public class OrderList {

    private static int[] intArray;
    private int nElems;

    public OrderList(int max) {
        intArray = new int[max];
        nElems = 0;
    }

    public int size() {
        return nElems;
    }

    // 猜数游戏
    // 二分查找
    public int find(int searchKey) {
        int lowerBound = 0;
        int upperBound = nElems - 1;
        int curIn;
        while (true) {
            curIn = (lowerBound + upperBound) / 2;
            if (intArray[curIn] == searchKey) {
                return curIn;
            } else if (lowerBound > upperBound) {
                return nElems;
            } else {
                if (intArray[curIn] < searchKey) {
                    lowerBound = curIn + 1;
                } else {
                    upperBound = curIn - 1;
                }
            }
        }
    }
    //按顺序插入
    public void insert(int value) {
        int j;
        for (j = 0; j < nElems; j++) {
            if (intArray[j] > value) {
                break;
            }
        }
        for (int k = nElems; k > j; k--) {
            intArray[k] = intArray[k - 1];
        }
        intArray[j] = value;
        nElems++;
    }
    
    public boolean delete(int value){
        int j=find(value);
        if(j==nElems){
            return false;
        }else{
            for(int k=j;k<nElems;k++){
                intArray[k]=intArray[k+1];
            }
            nElems--;
            return true;
        }
    }
    
    public void display(){
        for(int j=0;j<nElems;j++){
            System.out.print(intArray[j]+" ");
        }
        System.out.println();
    }
    
    public static void main(String[] args) {
        int maxSize=100;
        OrderList arr=new OrderList(maxSize);
        
        arr.insert(77);
        arr.insert(99);
        arr.insert(44);
        arr.insert(55);
        arr.insert(22);
        arr.insert(88);
        arr.insert(11);
        arr.insert(00);
        arr.insert(66);
        arr.insert(33);
        
        arr.display();
        
        int searchKey=11;
        if(arr.find(searchKey)!=arr.size()){
            System.out.println("found "+searchKey+":"+arr.find(searchKey));
        }else{
            System.out.println("can't found "+searchKey);
        }
        arr.delete(55);
        arr.display();
    }
}

　　效率

线性查找	O(N)
二分查找	O(log N)
无序数组插入	O(1)
有序数组插入	O(N)
无序数组删除	O(N)
有序数组删除	O(N)