What is a program to sort a two dimensional integer array?

Answer 1

Any multi-dimensional array can be flattened into a linear array. For instance,

[[1,2,3],[4,5,6],[7,8,9]]

can be flattened into

[1,2,3,4,5,6,7,8,9].

So a solution to your problem (certainly not the most efficient) would be to flatten the 2d array into a linear array, and sort using a traditional sorting algorithm or Arrays.sort. You would then insert the sorted elements back into the 2d array. This would have nlog(n) complexity.

An implementation below:

public static void sort2d(int[][] arr)

{

int r = arr.length;

int c = arr[0].length;

int[] flat = new int[r*c];

for (int i = 0; i < r; i++)

for (int j = 0; j < c; j++)

flat[i*c+j] = arr[i][j];

Arrays.sort(flat);

for (int i = 0; i < flat.length; i++)

arr[i/r][i%c] = flat[i];

}