PROBLEM #1720 (Decode XORed Array | Array, Bit Manipulation)

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.

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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]

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Example 2

Input: encoded = [6,2,7,3], first = 4
Output: [4,2,0,7,4]

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SOLUTIONS

BIT MANIPULATION

• JAVA

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