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// T.C: O(n)
// S.C: O(24) = O(1), since the remainders range from 0 to 23
class Solution {
    public int countCompleteDays(int[] hours) {
        int result = 0;
        int[] remainderCount = new int[24]; // Array to count frequencies of remainders
        
        for (int hour : hours) {
            int remainder = hour % 24; // Current remainder
            int complement = (24 - remainder) % 24; // Complement remainder
            
            // Add the frequency of the complement remainder
            result += remainderCount[complement];
            
            // Increment the frequency of the current remainder
            remainderCount[remainder]++;
        }
        
        return result;
    }
}