LeetCode 1748: Sum of Unique Elements Solution

Master LeetCode problem 1748 (Sum of Unique Elements), a easy challenge, with our optimized solutions in Java, C++, and Python. Explore detailed explanations, test your code in our interactive editor, and prepare for coding interviews.

1748. Sum of Unique Elements

Easy

Array Hash Table Counting

Problem Explanation

Explanation

To solve this problem, we can use a hashmap to keep track of the frequency of each element in the input array. Then, we iterate over the hashmap and sum up the unique elements (elements with frequency 1). Finally, we return the total sum.

Algorithm:
1. Initialize a hashmap to store the frequency of each element.
2. Iterate over the input array and update the frequency in the hashmap.
3. Iterate over the hashmap and sum up the unique elements.
4. Return the total sum.
Time Complexity: O(n) where n is the number of elements in the input array.
Space Complexity: O(n) for the hashmap.

Solution Code

class Solution {
    public int sumOfUnique(int[] nums) {
        Map<Integer, Integer> frequencyMap = new HashMap<>();
        int sum = 0;
        
        for (int num : nums) {
            frequencyMap.put(num, frequencyMap.getOrDefault(num, 0) + 1);
        }
        
        for (int key : frequencyMap.keySet()) {
            if (frequencyMap.get(key) == 1) {
                sum += key;
            }
        }
        
        return sum;
    }
}

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