Find the Row with the Maximum Number of 1's

You are given a non-empty grid MAT with 'N' rows and 'M' columns, where each element is either 0 or 1. All rows are sorted in ascending order.

Your task is to determine the index of the row that contains the maximum number of 1's.

Example:

For the given grid, the row with the maximum number of 1's is at index 1 (0-indexed).

Input:

The first line contains an integer ‘T’, representing the number of test cases. Then each test case is as follows:
The first line contains two space-separated integers ‘N’ and ‘M’, representing the number of rows and columns of the grid, respectively.
The following ‘N’ lines each contain ‘M’ space-separated integers, representing the rows of the grid.

Output:

For each test case, output the index of the row with the maximum number of 1's. Print each result on a new line.

Constraints:

• 1 <= T <= 100
• 1 <= N <= 50
• 1 <= M <= 50
• 0 <= MAT[i][j] <= 1

Note: If two rows have the same number of 1's, return the one with the smaller index. The actual output does not need to be printed explicitly; it has been handled. Just implement the function to achieve the result.