Sorted Matrix

You are given an N x N matrix 'MAT' of positive integers, where every row and column is sorted in non-decreasing order.

Your task is to return a list containing all elements of the matrix in sorted order.

For example :

If the matrix is:

10 20 30 40
15 20 35 42
27 29 37 46
32 33 38 49

The output will be the elements of matrix in sorted order:
10 15 20 20 27 29 30 32 33 35 37 38 40 42 46 49

Follow Up:

Can you solve this in O((N ^ 2) * log(N)) time and O(N) space complexity?

Input format :

The first line of input contains a single integer T, representing the number of test cases or queries to be run. 
Then the T test cases follow.

The first line of each test case contains a positive integer N, which represents the number of rows and columns in the matrix.

The next 'N' lines, each contains 'N' single space-separated positive integers representing the elements in a row of the matrix.

Output Format :

For each test case, print a single line containing the elements of the matrix in sorted order.

Note:

You do not need to print anything. It has already been taken care of. Just implement the given function.

Constraint :

1 <= T <= 10
1 <= N <= 100
1 <= MAT[i][j] <= 10^5

Time Limit: 1 sec