稀疏数组sparseArray详解

1.背景

2.代码

package com.ldp.structure.demo01SparseArray;

import org.junit.Test;

import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;

/**
 * @author 姿势帝-博客园
 * @address https://www.cnblogs.com/newAndHui/
 * @WeChat 851298348
 * @create 04/09 8:25
 * @description <p>
 * 博客:https://www.cnblogs.com/butingxue/p/16120794.html
 * </p>
 */
public class Test01 {
    @Test
    public void test01() {
        int[][] array = createArray();
        printArray(array, "二维数组");
        int[][] sparseArray = arrayToSparse(array);
        printArray(sparseArray, "稀疏数组");
        int[][] arrayNew = sparseToArray(sparseArray);
        printArray(arrayNew, "稀疏数组-->二维数组");
    }

    /**
     * 1.确定稀疏数组的行:遍历数组得到数组的值个数n,n+1作为稀疏数组的行
     * 2.稀疏数组的列为固定值3
     * 二维数组转为稀疏数组
     */
    public int[][] arrayToSparse(int[][] array) {
        // 确定数组有效值个数
        int row = 0, col = 0, n = 0;
        // 记录二维数组每个值的行列值,格式(行,列,值)
        LinkedList<String> arrayStrList = new LinkedList<>();
        for (int[] ints : array) {
            row++;
            col = 0;
            for (int anInt : ints) {
                col++;
                if (anInt != 0) {
                    n++;
                    // 行,列,值
                    String str = "" + (row - 1) + "," + (col - 1) + "," + anInt;
                    arrayStrList.addLast(str);
                }
            }
        }
        // 第一行是 行,列,个数
        String strFirst = "" + row + "," + col + "," + n;
        arrayStrList.addFirst(strFirst);
        // 创建稀疏数组对象
        int[][] sparseArray = new int[n + 1][3];
        for (int i = 0; i < (n + 1); i++) {
            String s = arrayStrList.get(i);
            // System.out.println(s);
            String[] rowStr = s.split(",");
            sparseArray[i][0] = Integer.valueOf(rowStr[0]);
            sparseArray[i][1] = Integer.valueOf(rowStr[1]);
            sparseArray[i][2] = Integer.valueOf(rowStr[2]);
        }
        return sparseArray;
    }

    /**
     * 稀疏数组转二维数组
     *
     * @param sparseArray
     * @return
     */
    public int[][] sparseToArray(int[][] sparseArray) {
        int row = sparseArray[0][0];
        int col = sparseArray[0][1];
        int n = sparseArray[0][2];
        int[][] array = new int[row][col];
        for (int i = 1; i < n; i++) {
            int row_ = sparseArray[i][0];
            int col_ = sparseArray[i][1];
            int value_ = sparseArray[i][2];
            array[row_][col_] = value_;
        }
        return array;
    }

    /**
     * 创建五子棋盘
     */
    public int[][] createArray() {
        int[][] array = new int[11][11];
        array[1][2] = 1;
        array[2][3] = 2;

        array[2][4] = 1;
        array[4][6] = 2;
        return array;
    }

    /**
     * 打印数组
     *
     * @param array
     */
    public void printArray(int[][] array, String message) {
        System.out.println("----------" + message + "-----start-----------");
        for (int[] ints : array) {
            for (int anInt : ints) {
                System.out.printf("%d\t", anInt);
            }
            System.out.println();
        }
        System.out.println("----------" + message + "------end------------");
    }
}