leetcode

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1748. Sum of Unique Elements

题目

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

题目大意

给你一个整数数组 nums 。数组中唯一元素是那些只出现 恰好一次 的元素。请你返回 nums 中唯一元素的 和 。

解题思路

• 简单题。利用 map 统计出每个元素出现的频次。再累加所有频次为 1 的元素，最后输出累加和即可。

代码

package leetcode

func sumOfUnique(nums []int) int {
	freq, res := make(map[int]int), 0
	for _, v := range nums {
		if _, ok := freq[v]; !ok {
			freq[v] = 0
		}
		freq[v]++
	}
	for k, v := range freq {
		if v == 1 {
			res += k
		}
	}
	return res
}