# ---
# title: 1310. XOR Queries of a Subarray
# id: problem1310
# author: Indigo
# date: 2021-05-14
# difficulty: Medium
# categories: Bit Manipulation
# link: <https://leetcode.com/problems/xor-queries-of-a-subarray/description/>
# hidden: true
# ---
# 
# Given the array `arr` of positive integers and the array `queries` where
# `queries[i] = [Li, Ri]`, for each query `i` compute the **XOR** of elements
# from `Li` to `Ri` (that is, `arr[Li] **xor** arr[Li+1] **xor** ... **xor**
# arr[Ri]` ). Return an array containing the result for the given `queries`.
# 
# 
# 
# **Example 1:**
# 
#     
#     
#     Input: arr = [1,3,4,8], queries = [[0,1],[1,2],[0,3],[3,3]]
#     Output: [2,7,14,8] 
#     Explanation: 
#     The binary representation of the elements in the array are:
#     1 = 0001 
#     3 = 0011 
#     4 = 0100 
#     8 = 1000 
#     The XOR values for queries are:
#     [0,1] = 1 xor 3 = 2 
#     [1,2] = 3 xor 4 = 7 
#     [0,3] = 1 xor 3 xor 4 xor 8 = 14 
#     [3,3] = 8
#     
# 
# **Example 2:**
# 
#     
#     
#     Input: arr = [4,8,2,10], queries = [[2,3],[1,3],[0,0],[0,3]]
#     Output: [8,0,4,4]
#     
# 
# 
# 
# **Constraints:**
# 
#   * `1 <= arr.length <= 3 * 10^4`
#   * `1 <= arr[i] <= 10^9`
#   * `1 <= queries.length <= 3 * 10^4`
#   * `queries[i].length == 2`
#   * `0 <= queries[i][0] <= queries[i][1] < arr.length`
# 
# 
## @lc code=start
using LeetCode

function xor_queries(arr::Vector{Int}, queries::Vector{Vector{Int}})
    pushfirst!(arr, 0)
    off_arr = OffsetArray(arr, -1)
    for i in 1:(length(arr) - 1)
        @inbounds off_arr[i] = off_arr[i] ⊻ off_arr[i - 1]
    end
    res = fill(0, length(queries))
    for (idx, q) in enumerate(queries)
        @inbounds res[idx] = off_arr[q[2] + 1] ⊻ off_arr[q[1]]
    end
    return res
end
## @lc code=end
