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Java-based LeetCode algorithm problem solutions, regularly updated

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package g1701_1800.s1748_sum_of_unique_elements;

// #Easy #Array #Hash_Table #Counting #2022_04_30_Time_2_ms_(54.08%)_Space_42_MB_(38.95%)

import java.util.HashMap;
import java.util.Map;

/**
 * 1748 - Sum of Unique Elements\.
 *
 * Easy
 *
 * You are given an integer array `nums`. The unique elements of an array are the elements that appear **exactly once** in the array.
 *
 * Return _the **sum** of all the unique elements of_ `nums`.
 *
 * **Example 1:**
 *
 * **Input:** nums = [1,2,3,2]
 *
 * **Output:** 4
 *
 * **Explanation:** The unique elements are [1,3], and the sum is 4.
 *
 * **Example 2:**
 *
 * **Input:** nums = [1,1,1,1,1]
 *
 * **Output:** 0
 *
 * **Explanation:** There are no unique elements, and the sum is 0.
 *
 * **Example 3:**
 *
 * **Input:** nums = [1,2,3,4,5]
 *
 * **Output:** 15
 *
 * **Explanation:** The unique elements are [1,2,3,4,5], and the sum is 15.
 *
 * **Constraints:**
 *
 * *   `1 <= nums.length <= 100`
 * *   `1 <= nums[i] <= 100`
**/
public class Solution {
    public int sumOfUnique(int[] nums) {
        Map map = new HashMap<>();
        int sum = 0;
        for (int num : nums) {
            map.put(num, map.getOrDefault(num, 0) + 1);
        }
        for (Map.Entry entry : map.entrySet()) {
            if (entry.getValue() == 1) {
                sum += entry.getKey();
            }
        }
        return sum;
    }
}