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2433 - Find the Original array of prefix XOR (Medium)

https://leetcode.com/problems/find-the-original-array-of-prefix-xor/

Problem Statement​

You are given an integer array pref of size n. Find and return the array arr of size n that satisfies:

  • pref[i] = arr[0] ^ arr[1] ^ ... ^ arr[i]. Note that ^ denotes the bitwise-xor operation.

It can be proven that the answer is unique.

Example 1:

Input: pref = [5,2,0,3,1]
Output: [5,7,2,3,2]
Explanation: From the array [5,7,2,3,2] we have the following:
- pref[0] = 5.
- pref[1] = 5 ^ 7 = 2.
- pref[2] = 5 ^ 7 ^ 2 = 0.
- pref[3] = 5 ^ 7 ^ 2 ^ 3 = 3.
- pref[4] = 5 ^ 7 ^ 2 ^ 3 ^ 2 = 1.

Example 2:

Input: pref = [13]
Output: [13]
Explanation: We have pref[0] = arr[0] = 13.

Constraints:

  • 1 <= pref.length <= 10^5
  • 0 <= pref[i] <= 10^6

Approach 1: STL​

Time Complexity: O(n)O(n), where nn - # of elements in the array

Space Complexity: O(n)O(n)

Written by @vigneshshiv
class Solution {
    public int[] findArray(int[] pref) {
        int[] nums = new int[pref.length];
        nums[0] = pref[0];
        for (int i = 1; i < pref.length; i++) {
            nums[i] = pref[i] ^ pref[i - 1];
        }
        return nums;
    }
}