基本介紹：

稀疏陣列的應用例項：

package com.model.DataStructures;

import java.io.*;
import java.util.ArrayList;
import java.util.HashMap;

/**
 * @Description:測試類
 * @Author: 張紫韓
 * @Crete 2021/6/23 11:39
 * 稀疏陣列的實現 棋盤案例
 */
public class SparseArrayDemo01 {
    public static void main(String[] args) throws
 
 IOException {
        /**
         * 建立一個原始的二維陣列代替棋盤
         * 白棋代表1
         * 黑棋代表2
         *
         * */
        int[][] arr1 = new int[11][11];
        //二行三列
        arr1[1][2]=1;
        //三行四列
        arr1[2][3]=2;
        System.out.println("原始的陣列");
        for (int[] arr2:arr1){
            
 
for (int val:arr2){
                System.out.printf("%d\t",val);
            }
            System.out.println();
        }

        System.out.println("*********************");
        System.out.println("轉成稀疏陣列");
        //找出原始陣列中的元素個數
        int sum=0;
        for (int i = 0; i < arr1.length; i++) {
            
 
for (int j = 0; j <arr1[i].length; j++) {
                if (arr1[i][j]!=0) {
                    sum++;
                }
            }
        }
        int[][] sparseArr = new int[sum+1][3];
        sparseArr[0][0]=11;
        sparseArr[0][1]=11;
        sparseArr[0][2]=sum;
        int row=1;
        for (int i = 0; i < arr1.length; i++) {
            for (int j = 0; j <arr1[i].length; j++) {
                if (arr1[i][j] != 0) {
                  sparseArr[row][0]=i;
                  sparseArr[row][1]=j;
                  sparseArr[row][2]=arr1[i][j];
                  row++;
                }
            }
        }
        for (int i = 0; i < sparseArr.length; i++) {
            for (int j = 0; j <sparseArr[i].length; j++) {
                    System.out.print(sparseArr[i][j]+"\t");
            }
            System.out.println();
        }
        System.out.println("*********************");
        System.out.println("將稀疏陣列儲存到檔案中");
        String filePath="D:\\qq\\IDEA\\IdeaProjects\\java_mianshi_test\\mianshi_suanfa\\src\\main\\resources\\File\\map.data";

        BufferedWriter writer=new BufferedWriter(new FileWriter(filePath));
        for (int i = 0; i < sparseArr.length; i++) {
            for (int j = 0; j <sparseArr[i].length; j++) {
               writer.write(sparseArr[i][j]+"\t");
            }
            writer.newLine();
        }
        writer.close();
        System.out.println("寫入成功");


        System.out.println("*********************");
        System.out.println("讀取檔案中的稀疏陣列,並轉換未二維陣列");
        BufferedReader reader = new BufferedReader(new FileReader(filePath));
        String readLine=null;
        String[] str=reader.readLine().split("\t");
        int len=Integer.parseInt(str[0]);
        int len1=Integer.parseInt(str[1]);
        int[][] sparseArr1=new int[len][len1];
        while ((readLine=reader.readLine())!=null){
            String[] f=readLine.split("\t");
            sparseArr1[Integer.parseInt(f[0])][Integer.parseInt(f[1])]=Integer.parseInt(f[2]);
        }
        reader.close();
        for (int i = 0; i < sparseArr1.length; i++) {
            for (int j = 0; j <sparseArr1[i].length; j++) {
                System.out.print(sparseArr1[i][j]+"\t");
            }
            System.out.println();
        }
        System.out.println("成功讀到檔案中的稀疏陣列");



        System.out.println("*********************");

        System.out.println("稀疏陣列轉換為普通的二維陣列");

        int[][] arr2=new int[sparseArr[0][0]][sparseArr[0][1]];
        for (int i = 1; i < sparseArr.length; i++) {
                arr2[sparseArr[i][0]][sparseArr[i][1]]=sparseArr[i][2];

        }
        for (int i = 0; i < arr2.length; i++) {
            for (int j = 0; j < arr2[i].length; j++) {
                System.out.printf("%d\t",arr2[i][j]);
            }
            System.out.println();
        }


    }

}