Introduction

In this blog post, we will explore how to solve the LeetCode problem "2433" using AI. LeetCode is a popular platform for preparing for coding interviews, and with the help of AI tools like Chatmagic, we can generate solutions quickly and efficiently - helping you pass the interviews and get the job offer without having to study for months.

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 <= 105 0 <= pref[i] <= 106

Explanation

Here's the solution to the problem:

• Key Idea: The core idea is to leverage the properties of the XOR operation. Specifically, a ^ a = 0 and a ^ 0 = a. Since pref[i] = arr[0] ^ arr[1] ^ ... ^ arr[i] and pref[i-1] = arr[0] ^ arr[1] ^ ... ^ arr[i-1], then pref[i] ^ pref[i-1] = arr[i].
• Iterative Calculation: We can iterate through the pref array, calculating each arr[i] by XORing pref[i] with pref[i-1]. The first element arr[0] is simply pref[0].

• In-place Modification (Optional): To save space, it is possible to perform the array modification in-place. But in this solution to improve readability a new array for results is created.

• Runtime & Storage Complexity: O(n) runtime, O(n) storage.

Code

    def find_array(pref: list[int]) -> list[int]:
    """
    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]

    Example 2:
    Input: pref = [13]
    Output: [13]
    """
    n = len(pref)
    arr = [0] * n
    arr[0] = pref[0]

    for i in range(1, n):
        arr[i] = pref[i] ^ pref[i-1]

    return arr