<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>

#include <vector>
using namespace std;

class Solution {
public:
    struct trieNode {
        trieNode* left = nullptr;
        trieNode* right = nullptr;
    };

    void insert(trieNode* root, int num) {
        trieNode* pCrawl = root;
        for (int i = 31; i >= 0; i--) {
            int ithbit = (num >> i) & 1;
            if (ithbit == 0) {
                if (pCrawl->left == nullptr) {
                    pCrawl->left = new trieNode();
                }
                pCrawl = pCrawl->left;
            } else {
                if (pCrawl->right == nullptr) {
                    pCrawl->right = new trieNode();
                }
                pCrawl = pCrawl->right;
            }
        }
    }

    int findMaxXor(trieNode* root, int num) {
        int maxXor = 0;
        trieNode* pCrawl = root;

        for (int i = 31; i >= 0; i--) {
            int ithbit = (num >> i) & 1;
            if (ithbit == 1) {
                if (pCrawl->left != nullptr) {
                    maxXor += (1 << i);
                    pCrawl = pCrawl->left;
                } else {
                    pCrawl = pCrawl->right;
                }
            } else {
                if (pCrawl->right != nullptr) {
                    maxXor += (1 << i);
                    pCrawl = pCrawl->right;
                } else {
                    pCrawl = pCrawl->left;
                }
            }
        }
        return maxXor;
    }

    int findMaximumXOR(vector<int>& nums) {
        trieNode* root = new trieNode();
        for (int num : nums) {
            insert(root, num);
        }

        int rs = 0;
        for (int num : nums) {
            int temp = findMaxXor(root, num);
            rs = max(rs, temp);
        }

        return rs;
    }
};

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