Minimum Number of Platforms Required

You are provided with two arrays, AT and DT, representing the arrival and departure times of all trains arriving at a railway station.

Your task is to determine the minimum number of platforms needed at the railway station so that no train has to wait.

Example:

Input:

T = 1
N = 3
AT = [900, 940, 950]
DT = [910, 1200, 1120]

Output:

2

Explanation:

The first train departs at 910. The second train arrives shortly after at 940 and will need a new platform. The third train arrives at 950 while the second is still stationed, necessitating a total of 2 platforms.

Constraints:

• 1 <= T <= 10
• 1 <= N <= 50000
• 0 <= AT[i] <= DT[i] <= 2359
• Time is given in 24H format, without colons

Note:

No need to print the output, just implement the function to return the required result. Consider solving the problem in O(N) time and O(1) space if possible.