1720. Decode X O Red Array

# 1720. Decode XORed Array#

## 题目 #

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 <= 10^5`

## 解题思路 #

• 简单题。按照题意，求返回解码以后的原数组，即将编码后的数组前后两两元素依次做异或 `XOR` 运算。

## 代码 #

``````package leetcode

func decode(encoded []int, first int) []int {
arr := make([]int, len(encoded)+1)
arr[0] = first
for i, val := range encoded {
arr[i+1] = arr[i] ^ val
}
return arr
}
``````

Apr 8, 2023