# 1720. Decode XORed Array

Easy
There is a hidden integer array `arr` that consists of `n` non-negative integers.
It was encoded into another integer array `encoded` of length `n - 1`, such that `encoded[i] = arr[i] XOR arr[i + 1]`. For example, if `arr = [1,0,2,1]`, then `encoded = [1,2,3]`.
You are given the `encoded` array. You are also given an integer `first`, that is the first element of `arr`, i.e. `arr[0]`.
Return the original array `arr`. It can be proved that the answer exists and is unique.
Example 1:
Input: encoded = [1,2,3], first = 1
Output:
[1,0,2,1]
Explanation:
If arr = [1,0,2,1], then first = 1 and encoded = [1 XOR 0, 0 XOR 2, 2 XOR 1] = [1,2,3]
Example 2:
Input: encoded = [6,2,7,3], first = 4
Output:
[4,2,0,7,4]
Constraints:
• `2 <= n <= 104`
• `encoded.length == n - 1`
• `0 <= encoded[i] <= 105`
• `0 <= first <= 105`

### 解題

func decode(encoded []int, first int) []int {
res := make([]int, 0)
res = append(res, first)
res = append(res, encoded...)
for i:=1; i<len(res); i++ {
res[i] = res[i] ^ res[i-1]
}
return res
}