Java--算法--稀疏数组

1. 稀疏数组的应用场景：
   1. 

2. 基本介绍：

   1. 
   2. 

       

       

3. 稀疏数组的应用实例：

   1. 

4.  

   package com.model.DataStructures;
   
   import java.io.*;
   import java.util.ArrayList;
   import java.util.HashMap;
   
   /**
    * @Description:测试类
    * @Author: 张紫韩
    * @Crete 2021/6/23 11:39
    * 稀疏数组的实现 棋盘案例
    */
   public class SparseArrayDemo01 {
       public static void main(String[] args) throws IOException {
           /**
            * 创建一个原始的二维数组代替棋盘
            * 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("原始的数组");
           for (int[] arr2:arr1){
               for (int val:arr2){
                   System.out.printf("%d\t",val);
               }
               System.out.println();
           }
   
           System.out.println("*********************");
           System.out.println("转成稀疏数组");
           //找出原始数组中的元素个数
           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("将稀疏数组保存到文件中");
           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("写入成功");
   
   
           System.out.println("*********************");
           System.out.println("读取文件中的稀疏数组,并转换未二维数组");
           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("成功读到文件中的稀疏数组");
   
   
   
           System.out.println("*********************");
   
           System.out.println("稀疏数组转换为普通的二维数组");
   
           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();
           }
   
   
       }
   
   }