LeetCode-in-All
136. Single Number
Easy
Given a non-empty array of integers nums, every element appears twice except for one. Find that single one.
You must implement a solution with a linear runtime complexity and use only constant extra space.
Example 1:
Input: nums = [2,2,1]
Output: 1
Example 2:
Input: nums = [4,1,2,1,2]
Output: 4
Example 3:
Input: nums = [1]
Output: 1
Constraints:
1 <= nums.length <= 3 * 104-3 * 104 <= nums[i] <= 3 * 104- Each element in the array appears twice except for one element which appears only once.
Solution
defmodule Solution do
@spec single_number(nums :: [integer]) :: integer
def single_number(nums) do
nums
|> Enum.frequencies()
|> Enum.find(fn {k, v} -> v == 1 end)
|> elem(0)
end
end