<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 Trie {
    struct trieNode {
        trieNode * children[2];
    };

    trieNode * getNode() {
        trieNode * newNode = new trieNode();
        for (int i = 0; i < 2; i++) {
            newNode->children[i] = NULL;
        }
        return newNode;
    }

    trieNode * root;

public:
    Trie() {
        root = getNode();
    }

    void insert(string s) {
        trieNode * crawler = root;
        for (int i = 0; i < s.size(); i++) {
            char ch = s[i];
            int idx = ch-'0';
            if (crawler->children[idx] == NULL) {
                crawler->children[idx] = getNode();
            }
            crawler = crawler->children[idx];
        }
    }

    int find_max(string s) {
        int output = 0;
        trieNode * crawler = root;
        for (int i = 0; i < s.size(); i++) {
            int bit = !(s[i]-'0');
            if (crawler->children[bit]) {
                output = output | (1 << (31-i));
                crawler = crawler->children[bit];
            } else if (crawler->children[!bit]) {
                crawler = crawler->children[!bit];
            }
        }
        // output >> 2;
        return output;
    }
};

class Solution {
public:
    int findMaximumXOR(vector<int>& nums) {
        Trie t;
        for (int i: nums) {
            string s = bitset<32>(i).to_string();
            cout << s << endl;
            t.insert(s);
        }
        int maxi = 0;
        for (int i: nums) {
            maxi = max(maxi, t.find_max(bitset<32>(i).to_string()));
        }
        return maxi;
    }
};
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