public static void main(String[] args) {
        int[][] arr={{1,2,3},{1,2,3},{1,2,3}};
        NumMatrix numMatrix=new NumMatrix(arr);
        System.out.println(numMatrix.getRangeSum(1,1));
        System.out.println(numMatrix.getRangeSum(0,1));
        System.out.println(numMatrix.sumRegion(1,1,1,1));
    }