<p>Given an integer array <code>nums</code>, return <em>the maximum result of </em><code>nums[i] XOR nums[j]</code>, where <code>0 &lt;= i &lt;= j &lt; n</code>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> nums = [3,10,5,25,2,8]
<strong>Output:</strong> 28
<strong>Explanation:</strong> The maximum result is 5 XOR 25 = 28.
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> nums = [14,70,53,83,49,91,36,80,92,51,66,70]
<strong>Output:</strong> 127
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= nums.length &lt;= 2 * 10<sup>5</sup></code></li>
	<li><code>0 &lt;= nums[i] &lt;= 2<sup>31</sup> - 1</code></li>
</ul>

class TreeNode:
    def __init__(self):
        self.left = None
        self.right = None


class Solution:
    def findMaximumXOR(self, nums: List[int]) -> int:
        n = len(nums)
        root = TreeNode()

        def add(num):
            nonlocal root
            cur = root
            for k in range(30, -1, -1):
                bit = (num >> k) & 1
                node = TreeNode()
                if bit == 1:
                    if not cur.left:
                        cur.left = node
                    cur = cur.left
                else:
                    if not cur.right:
                        cur.right = node
                    cur = cur.right
        
        def search(num):
            nonlocal root
            cur = root
            x = 0
            for k in range(30, -1, -1):
                 bit = (num >> k) & 1
                 if bit == 1:
                    if cur.right:
                        cur = cur.right
                        x = x * 2 + 1
                    else:
                        cur = cur.left
                        x = x * 2
                 else:
                    if cur.left:
                        cur = cur.left
                        x = x * 2 + 1
                    else:
                        cur = cur.right
                        x = x * 2
            return x

        add(nums[0])
        ans = 0
        for i in range(1, n):
            num = nums[i]
            # search 
            ans = max(ans, search(num))
            # add
            add(num)
        return ans
            

             
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