Decode XORed Permutation - LeetCode solutions

Problem

There is an integer array perm that is a permutation of the first n positive integers, where n is always odd.

It was encoded into another integer array encoded of length n - 1, such that encoded[i] = perm[i] XOR perm[i + 1]. For example, if perm = [1,3,2], then encoded = [2,1].

Given the encoded array, return the original array perm. It is guaranteed that the answer exists and is unique.

Example 1:

Input: encoded = [3,1]
Output: [1,2,3]
Explanation: If perm = [1,2,3], then encoded = [1 XOR 2,2 XOR 3] = [3,1]

Example 2:

Input: encoded = [6,5,4,6]
Output: [2,4,1,5,3]

Constraints:

3 <= n < 10^5
n is odd.
encoded.length == n - 1

Solution (Java)

class Solution {
    public int[] decode(int[] encoded) {
        int[] decoded = new int[encoded.length + 1];
        for (int i = 1; i < encoded.length; i = i + 2) {
            decoded[0] = decoded[0] ^ encoded[i];
            decoded[0] = decoded[0] ^ i;
            decoded[0] = decoded[0] ^ i + 1;
        }
        decoded[0] = decoded[0] ^ decoded.length;
        for (int i = 1; i < decoded.length; i++) {
            decoded[i] = decoded[i - 1] ^ encoded[i - 1];
        }
        return decoded;
    }
}

Explain:

nope.

Complexity:

Time complexity : O(n).
Space complexity : O(n).