【数据结构】稀疏数组实现，存在问题：当有效值过多，稀疏数组反而会消耗性能

public class SparseArray {

    public static void main(String[] args) {
        int[][] oldArray = new int[11][11];
        oldArray[1][2] = 1;
        oldArray[2][3] = 2;
        int[][] sparse = saveArray(oldArray);
        int[][] newArr = readArray(sparse);
        printArr(newArr);
    }

    private static int[][] readArray(int[][] sparse) {
        int[][] newArr = new int[sparse[0][0]][sparse[0][1]];
        for (int i = 1; i < sparse.length; i++) {
            newArr[sparse[i][0]][sparse[i][1]] = sparse[i][2];
        }
        return newArr;
    }

    private static int[][] saveArray(int[][] oldArray) {
        printArr(oldArray);
        int rowLength = oldArray.length;
        int colLength = oldArray[0].length;
        int sum = 0;
        for (int i = 0; i < rowLength; i++) {
            for (int j = 0; j < colLength; j++) {
                if(0 != oldArray[i][j]){
                    sum++;
                }
            }
        }

        int[][] sparseArray = new int[sum+1][3];
        sparseArray[0][0] = rowLength;
        sparseArray[0][1] = colLength;
        sparseArray[0][2] = sum;

        int sparseRow = 1;
        for (int i = 0; i < rowLength; i++) {
            for (int j = 0; j < colLength; j++) {
                if(0 != oldArray[i][j]){
                    sparseArray[sparseRow][0] = i;
                    sparseArray[sparseRow][1] = j;
                    sparseArray[sparseRow][2] = oldArray[i][j];
                    sparseRow++;
                }
            }
        }
        return sparseArray;
    }

    private static void printArr(int[][] arr) {
        for (int[] row : arr) {
            for (int data : row) {
                System.out.printf("%d\t", data);
            }
            System.out.println();
        }
    }

}