JAVA 二维数组与稀疏数组转换

public class Main {

    private int[][] commonArray;

    public static void main(String[] args) {

        Main main =  new Main();
        main.initCommonArray();
        int[][] sparseArray = main.toSparseArray(main.commonArray);
        main.toCommonArray( sparseArray );
    }


    public  void initCommonArray(){
        commonArray = new int[9][9];
        commonArray[1][1]  = 2;
        commonArray[2][2]  = 3;

        System.out.println("普通数组为: ");
        for ( int i=0; i<9; i++  ){
            for ( int j=0; j<9; j++ ){
                System.out.print(commonArray[i][j] + " ");
            }
            System.out.println();
        }
        System.out.println();
    }


    /**
     *   二维数组转稀疏数组
     * */
    public  int[][]  toSparseArray( int[][] commonArray ) {


        if ( commonArray != null && commonArray.length > 0 ){

            //获取数组的长宽
            int totalLength = commonArray.length;
            int totalWidth  = commonArray[0].length;

            //扫描数组的有效数据的长度
            int availableCount = 0;
            for ( int i=0; i<commonArray.length; i++ ){

                int[] temp = commonArray[i];
                for ( int j=0; j<temp.length; j++ ){

                    if ( commonArray[i][j] != 0 ){
                        availableCount++;
                    }
                }
            }

            int[][] spareArray = new int[availableCount+1][3];
            spareArray[0][0] = totalLength; //存二维数组的长度
            spareArray[0][1] = totalWidth;  //存二维数组的宽度
            spareArray[0][2] = 0; //存二维数组中初始化的值
            int k = 1;
            for ( int i=0; i<commonArray.length; i++ ){

                int[] temp = commonArray[i];
                for ( int j=0; j<temp.length; j++ ){

                    if ( commonArray[i][j] != 0 ){
                        spareArray[k][0] = i;
                        spareArray[k][1] = j;
                        spareArray[k][2] = commonArray[i][j];
                        k++;
                    }
                }
            }

            System.out.println("转换成的稀疏数组为: ");
            for ( int i=0; i<spareArray.length; i++ ){

                int[] temp = spareArray[i];
                for ( int j=0; j<temp.length; j++ ){

                    System.out.print(spareArray[i][j] + "  ");
                }
                System.out.println();
            }
            System.out.println();
            return spareArray;
        }

        return null;
    }


    /**
     *  稀疏数组转二维数组
     * */
    public  void toCommonArray( int[][] sparseArray ){


        if ( sparseArray == null  || sparseArray.length  == 0 ){
            return;
        }

        //根据第一行获取二维数组的高宽，以及默认值
        int height = sparseArray[0][0];
        int width  = sparseArray[0][1];
        int defaultValue = sparseArray[0][2];
        int[][] commonArray = new int[height][width];
        for ( int i=0; i<height; i++ ){
            for ( int j=0; j<width; j++ ){
                commonArray[i][j] = defaultValue;
            }
        }

        //将有效数据填充到数组中
        for ( int i=1; i<sparseArray.length; i++ ){
                int y = sparseArray[i][0];
                int x = sparseArray[i][1];
                int value = sparseArray[i][2];
                commonArray[y][x] = value;
        }


        System.out.println("稀疏矩阵转普通数组为: ");
        for ( int i=0; i<height; i++ ){
            for ( int j=0; j<width; j++ ){
                System.out.print(commonArray[i][j] + " ");
            }
            System.out.println();
        }
    }
}