Java稀疏数组实现

压缩

//压缩
    public static int[][] toXS(int[][] sum) {
        //获取原数组行，列，非0数量
        int count = 0;//非0数量
        int lin = 0;//行
        int row = 0;//列
        for (int[] a1 : sum) {
            for (int b : a1) {
                if (b != 0) {
                    ++count;
                }
            }
            lin++;
            row = a1.length;
        }
        int[][] yzm = new int[count + 1][3];//初始化
        yzm[0][0] = lin;
        yzm[0][1] = row;
        yzm[0][2] = count;
        for (int i = 0; i < lin; i++) {
            for (int j = 0; j < row; j++) {
                if (sum[i][j] != 0) {
                    yzm[count][0] = i;
                    yzm[count][1] = j;
                    yzm[count][2] = sum[i][j];
                    --count;
                }
            }
        }
        return yzm;
    }

还原

//还原
    public static int[][] toArray(int[][] yzm) {
        int[][] num = new int[yzm[0][0]][yzm[0][1]];
        for (int i = 1; i <= yzm[0][2]; i++) {//i从1开始，到i=count
            num[yzm[i][0]][yzm[i][1]] = yzm[i][2];
        }
        return num;
    }

输出

public static void outTo(int[][] num) {
        for (int[] num1 : num) {
            for (int num2 : num1) {
                System.out.print(num2 + "\t");
            }
            System.out.println();
        }
    }

Test

public static void main(String[] args) {
        /*
       稀疏数组，三元数组 sum[原数组非0数总数+1][3]
       sum[0][0]=原数组总行数 sum[0][1]=原数组总列数  sum[0][2]=原数组非0数总数
       sum[1++][0]=非0数行 sum[1++][1]=非0数列  sum[1++][2]=非0数
        */
        int[][] array = new int[6][7];
        array[3][2]=1;
        array[5][4]=2;
        array[3][1]=1;
        array[2][2]=3;
        int [][] sum,num;
        sum=toXS(array);
        outTo(array);
        outTo(sum);
        num=toArray(sum);
        outTo(num);
    }