Как заполнить массив змейкой java

int rows = 4;
int columns = 5;
int[][] arr = new int[rows][columns];

for(int n = 0; n < rows*columns; n++) {
    int i = n / columns;
    int j = i % 2 == 0 ? n % columns : columns - 1 - n % columns;
    arr[i][j] = n;
}

System.out.println(Arrays.deepToString(arr));
// => [[0, 1, 2, 3, 4], [9, 8, 7, 6, 5], [10, 11, 12, 13, 14], [19, 18, 17, 16, 15]]