Formatted question description: https://leetcode.ca/all/1748.html
1748. Sum of Unique Elements
Level
Easy
Description
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
Solution
Use a hash map to store each number’s occurrence in nums
. Then loop over the hash map and calculate the sum of the elements that occur only once.
class Solution {
public int sumOfUnique(int[] nums) {
Map<Integer, Integer> map = new HashMap<Integer, Integer>();
for (int num : nums) {
int count = map.getOrDefault(num, 0) + 1;
map.put(num, count);
}
int sum = 0;
Set<Integer> set = map.keySet();
for (int num : set) {
int count = map.get(num);
if (count == 1)
sum += num;
}
return sum;
}
}