Leetcode 136 problem.

Given a non-empty array of integers nums, every element appears twice except for one. Find that single one.

Go

• Time complexity: $O(n)$ - n is a length of a number array
• Auxiliary space: $O(1)$ - constant amount of space

func singleNumber(nums []int) int {
    singleNumber := 0

    for _, n := range nums {
        singleNumber ^= n
    }

    return singleNumber
}