题目：
题解：
python
class Trie:
def __init__(self):
# 左子树指向表示 0 的子节点
self.left = None
# 右子树指向表示 1 的子节点
self.right = None
class Solution:
def findMaximumXOR(self, nums: List[int]) -> int:
# 字典树的根节点
root = Trie()
# 最高位的二进制位编号为 30
HIGH_BIT = 30
def add(num: int):
cur = root
for k in range(HIGH_BIT, -1, -1):
bit = (num >> k) & 1
if bit == 0:
if not cur.left:
cur.left = Trie()
cur = cur.left
else:
if not cur.right:
cur.right = Trie()
cur = cur.right
def check(num: int) -> int:
cur = root
x = 0
for k in range(HIGH_BIT, -1, -1):
bit = (num >> k) & 1
if bit == 0:
# a_i 的第 k 个二进制位为 0，应当往表示 1 的子节点 right 走
if cur.right:
cur = cur.right
x = x * 2 + 1
else:
cur = cur.left
x = x * 2
else:
# a_i 的第 k 个二进制位为 1，应当往表示 0 的子节点 left 走
if cur.left:
cur = cur.left
x = x * 2 + 1
else:
cur = cur.right
x = x * 2
return x
n = len(nums)
x = 0
for i in range(1, n):
# 将 nums[i-1] 放入字典树，此时 nums[0 .. i-1] 都在字典树中
add(nums[i - 1])
# 将 nums[i] 看作 ai，找出最大的 x 更新答案
x = max(x, check(nums[i]))
return x