Capture Region Problem Statement

You are given a matrix having N rows and M columns. Each cell of the matrix contains either 'X' or 'O'. Your task is to flip all the regions of 'O' that are completely surrounded by 'X'. This means you need to change all 'O's in the surrounded region to 'X'.

Input:

The first line contains an integer 'T' representing the number of test cases.

For each test case, the first line contains two space-separated integers, 'N' and 'M', describing the dimensions of the matrix.
In the next 'N' lines, each line contains a string of length 'M' consisting of 'X' and 'O'.

Output:

For each test case, output the modified matrix with N lines, each containing M characters, where surrounded 'O' regions are flipped to 'X'.
The result of each test case should be printed on a new line.

Example:

Constraints:

• 1 <= T <= 50
• 1 <= N <= 10^4
• 1 <= M <= 10^4
• 1 <= N * M <= 10^4

Note:

1. O's on the matrix border are not flipped since they are not surrounded.
2. A region of 'O's is considered surrounded if all boundary cells of the region contain 'X'.