LeetCode 1904: The Number of Full Rounds You Have Played Solution

class Solution {
    public int numberOfRounds(String startTime, String finishTime) {
        int startMinutes = Integer.parseInt(startTime.substring(0, 2)) * 60 + Integer.parseInt(startTime.substring(3));
        int finishMinutes = Integer.parseInt(finishTime.substring(0, 2)) * 60 + Integer.parseInt(finishTime.substring(3));
        
        if (finishMinutes < startMinutes) {
            finishMinutes += 24 * 60; // add 24 hours in minutes
        }
        
        int startRound = (startMinutes + 14) / 15 * 15; // starting full round after loginTime
        int endRound = finishMinutes / 15 * 15; // ending full round before logoutTime
        
        return Math.max(0, (endRound - startRound) / 15);
    }
}