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

**Note:**

Your algorithm should have a linear runtime complexity. Could you implement it without using extra memory?

Example 1:

Input: [2,2,1]

Output: 1

Example 2:Input: [4,1,2,1,2]

Output: 4

```
func singleNumber(nums []int) int {
result := 0
for _, v := range nums {
result ^= v
}
return result;
}
```