LeetCode in Kotlin

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

Solution

class Solution {
    fun decode(encoded: IntArray, first: Int): IntArray {
        val arr = IntArray(encoded.size + 1)
        arr[0] = first
        for (i in encoded.indices) {
            arr[i + 1] = encoded[i] xor arr[i]
        }
        return arr
    }
}

This site is open source. Improve this page.