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59 lines
1.7 KiB
Markdown
59 lines
1.7 KiB
Markdown
# [1720. Decode XORed Array](https://leetcode.com/problems/decode-xored-array/)
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## 题目
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There is a **hidden** integer array `arr` that consists of `n` non-negative integers.
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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]`.
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You are given the `encoded` array. You are also given an integer `first`, that is the first element of `arr`, i.e. `arr[0]`.
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Return *the original array* `arr`. It can be proved that the answer exists and is unique.
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**Example 1:**
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```
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Input: encoded = [1,2,3], first = 1
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Output: [1,0,2,1]
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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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```
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**Example 2:**
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```
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Input: encoded = [6,2,7,3], first = 4
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Output: [4,2,0,7,4]
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```
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**Constraints:**
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- `2 <= n <= 104`
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- `encoded.length == n - 1`
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- `0 <= encoded[i] <= 105`
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- `0 <= first <= 10^5`
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## 题目大意
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未知 整数数组 arr 由 n 个非负整数组成。经编码后变为长度为 n - 1 的另一个整数数组 encoded ，其中 encoded[i] = arr[i] XOR arr[i + 1] 。例如，arr = [1,0,2,1] 经编码后得到 encoded = [1,2,3] 。给你编码后的数组 encoded 和原数组 arr 的第一个元素 first（arr[0]）。请解码返回原数组 arr 。可以证明答案存在并且是唯一的。
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## 解题思路
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- 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。
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## 代码
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```go
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package leetcode
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func decode(encoded []int, first int) []int {
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arr := make([]int, len(encoded)+1)
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arr[0] = first
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for i, val := range encoded {
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arr[i+1] = arr[i] ^ val
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}
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return arr
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}
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``` |