數組應用——二維數組轉稀疏數組、循環隊列

1.數組實現循環隊列

import java.util.Scanner;

public class CircleArrayQueueDemo {
    public static void main(String[] args) {
        //測試循環隊列
        //創建一個隊列
        CircleArray queue = new CircleArray(4);//有效數據最大爲3
        char key = ' ';//接受用戶輸入
        Scanner scanner = new Scanner(System.in);
        boolean loop = true;
        while (loop){
            System.out.println("s(show):顯示隊列");
            System.out.println("e(exit):退出程序");
            System.out.println("a(add):添加數據到隊列");
            System.out.println("g(get):從隊列取出數據");
            System.out.println("h(head):查看隊列頭的數據");
            key = scanner.next().charAt(0);
            switch (key){
                case 's'://展示數據
                    queue.showQueue();
                    break;
                case 'a'://添加數據
                    System.out.println("輸入一個數：");
                    int value = scanner.nextInt();
                    queue.addQueue(value);
                    break;
                case 'g'://取出數據
                    try{
                        int res = queue.getQueue();
                        System.out.printf("取出的數據是:%d\n",res);
                    }catch (RuntimeException e){
                        System.out.println(e.getMessage());
                    }
                    break;
                case 'h'://查看隊列頭數據
                    try{
                        int res = queue.headQueue();
                        System.out.printf("隊列頭數據是:%d\n",res);
                    }catch (RuntimeException e){
                        System.out.println(e.getMessage());
                    }
                    break;
                case 'e':
                    scanner.close();
                    loop = false;
                    break;
                default:
                    break;
            }
        }
        System.out.println("程序退出！！！");
    }
}

class CircleArray {
    private int maxSize;//數組最大容量
    private int front;//隊列第一個元素
    private int rear;//隊列最後一個元素的後一個位置
    private int[] arr;//用於存放數據，模擬隊列

    public CircleArray(int maxSize) {
        this.maxSize = maxSize;
        arr = new int[maxSize];
    }
    //判斷隊列是否滿
    public boolean isFull(){
        return (rear+1)%maxSize==front;
    }
    //判斷隊列是否爲空
    public  boolean isEmpty(){
        return rear==front;
    }
    //添加數據到隊列
    public void addQueue(int n){
        //判斷隊列是否滿
        if (isFull()){
            System.out.println("隊列滿，不能加入數據");
            return;
        }
        arr[rear]=n;
        rear = (rear+1)%maxSize;
    }
    public int getQueue(){
        //判斷是否爲空
        if (isEmpty()){
            //通過拋出異常
            throw new RuntimeException("隊列空，不能取數據");
        }
        int value = arr[front];
        front = (front + 1)%maxSize;
        return value;
    }
    //顯示隊列所有數據
    public void showQueue(){
        //遍歷
        if (isEmpty()){
            System.out.println("隊列空，沒有數據");
            return;
        }
        for (int i = front; i < front+size(); i++) {
            System.out.printf("arr[%d]=%d\n",i%maxSize,arr[i%maxSize]);
        }
    }
    //求出當前隊列有效數據的個數
    public int size(){
        return (rear+maxSize-front)%maxSize;
    }
    //顯示隊列的頭數據，注意不是取數據
    public int headQueue(){
        //判斷
        if (isEmpty()){
            throw new RuntimeException("隊列空，沒有數據");
        }
        return arr[front];
    }
}

2.二維數組轉稀疏數組

public class SparseArray {
    public static void main(String[] args) {
        //創建一個原始的二維數組
        //0：無棋子，1：表示黑子，2：表示白子
        int[][] chessArray = new int[11][11];
        chessArray[1][2] = 1;
        chessArray[2][3] = 2;
        //輸出原始二維數組
        System.out.println("原始二維數組:");
        for (int[] row : chessArray) {
            for (int data : row) {
                System.out.printf("%d\t",data);
            }
            System.out.println();
        }

        //遍歷二維數組，轉稀疏數組
        int sum = 0;
        for (int i = 0; i < 11; i++) {
            for (int j = 0; j < 11; j++) {
                if (chessArray[i][j]!=0){
                    sum++;
                }
            }
        }
        //創建對應稀疏數組
        int[][] sparseArray = new int[sum+1][3];
        //給稀疏數組賦值
        sparseArray[0][0] = 11;
        sparseArray[0][1] = 11;
        sparseArray[0][2] = sum;
        //遍歷二維數組，將非0值存放到spareArray中
        int count = 0;//用於記錄是第幾個非零值
        for (int i = 0; i < 11; i++) {
            for (int j = 0; j < 11; j++) {
                if (chessArray[i][j]!=0){
                    count++;
                    sparseArray[count][0]=i;
                    sparseArray[count][1]=j;
                    sparseArray[count][2]=chessArray[i][j];
                }
            }
        }
        //輸出稀疏數組
        System.out.println();
        System.out.println("得到的稀疏數組：");
        for (int i = 0; i < sparseArray.length; i++) {
            System.out.printf("%d\t%d\t%d\t\n",sparseArray[i][0],sparseArray[i][1],sparseArray[i][2]);
        }
        System.out.println();

        //稀疏數組轉二維數組
        int[][] chessArray2 = new int[sparseArray[0][0]][sparseArray[0][1]];
        //讀取稀疏數組數據，給二維數組賦值
        for (int i = 1; i < sparseArray.length; i++) {
            chessArray2[sparseArray[i][0]][sparseArray[i][1]]=sparseArray[i][2];
        }
        System.out.println();
        System.out.println("恢復後的二維數組：");
        for (int[] row : chessArray2) {
            for (int data : row) {
                System.out.printf("%d\t",data);
            }
            System.out.println();
        }
    }
}