Mock Interview: Apple

811. Subdomain Visit Count

class Solution {
    public List<String> subdomainVisits(String[] cpdomains) {
        Map<String, Integer> m = new HashMap<String, Integer>();
        
        for (String s : cpdomains) {
            String[] num = s.split("\\s+");
            int c = Integer.valueOf(num[0]);
            String[] parts = num[1].split("\\.");
            
            String site = "";
            
            for (int i = parts.length - 1; i >= 0; i--) {
                if (i < parts.length - 1) {
                    site = parts[i] + "." + site;
                } else {
                    site = parts[i] + site;
                }
                
                m.put(site, m.getOrDefault(site, 0) + c);
            }
        }
            
        List<String> result = new ArrayList<String>();
            
        for (String key : m.keySet()) {
            result.add(m.get(key) + " " + key);
        }
            
        return result; 
        
    }
}

Runtime: 32 ms, faster than 27.58% of Java online submissions for Subdomain Visit Count.
Memory Usage: 41.5 MB, less than 19.52% of Java online submissions for Subdomain Visit Count.

961. N-Repeated Element in Size 2N Array

class Solution {
    public int repeatedNTimes(int[] nums) {
        boolean found = false;
        int i = 0;
        int length = (nums.length-1) / 2;
        Arrays.sort(nums);
        while (! found) {
            if (nums[i] == nums[i+length]) {
                return nums[i];
            } else {
                i++;
            }
        }
        
        return -1;
//         Arrays.sort(nums);
        
//         if (nums.length % 2 == 0) {
//             int firsthalf = nums[nums.length / 4];
//             int lasthalf = nums[3 * nums.length / 4];
//             int middle = nums[nums.length / 2];

//             return (middle == firsthalf) ? firsthalf : lasthalf;
//         } else {
//             return nums[nums.length / 2];
//         }
        
    }
}

Runtime: 5 ms, faster than 38.49% of Java online submissions for N-Repeated Element in Size 2N Array.
Memory Usage: 40 MB, less than 38.23% of Java online submissions for N-Repeated Element in Size 2N Array.

처음에는 반값 찾기 법칙을 쓰려고 했는데
짧은거는 안된다는 걸 꺠닫고 n개 후 같은게 나올때까지 돌렸읍니다

루션이

class Solution {
    public int repeatedNTimes(int[] A) {
        for (int k = 1; k <= 3; ++k)
            for (int i = 0; i < A.length - k; ++i)
                if (A[i] == A[i+k])
                    return A[i];

        throw null;
    }
}

Runtime: 0 ms, faster than 100.00% of Java online submissions for N-Repeated Element in Size 2N Array.
Memory Usage: 39.8 MB, less than 55.46% of Java online submissions for N-Repeated Element in Size 2N Array.

제꺼랑 아이디어는 같은거 같은데.. 이렇게 하면 훨씬 빨라지네요~