我被一个竞争性编程档案中的这个问题困住了，它说：
Given an array of integers A of length n, we need to find the minimum length
subarray such that it has a subsequence with an xor sum of 0. (Subarray is a
contiguous segment of an array and subsequence is a sequence that can be
derived from a subarray by deleting zero or more elements.) The resulting
subarray must have a length of at least 1. (Empty subarray cannot be an answer.)
1 <= n <= 10^5
1 <= …