<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>

struct TrieNode {
    TrieNode* child[2];
    bool endFlag;
    char data;

    TrieNode(char ch){
        data = ch;
        for(int i=0; i<2; i++){
            child[i] = NULL;
        }
        endFlag = false;
    }
};

class Solution {
private:
    TrieNode* root = new TrieNode('0');
public:
    void insert(string word) {
        int index = word[0] - '0';
        int i = 0;
        TrieNode* node = root;
        while(i < word.length()){
            int index =  word[i] - '0';
            if(node -> child[index] == NULL){
                TrieNode* newNode = new TrieNode(word[i]);
                node -> child[index] = newNode;
            }
            node = node -> child[index];
            if(i == word.length()-1) node -> endFlag = true;
            i++;
        }
    }

    int search(string word) {
        int index = word[0] - '0';
        int toFind = index;
        int i = 0;
        int count = 0;
        TrieNode* node = root;
        while(i < word.length()){
            index = word[i] - '0';
            toFind = abs(index-1);
            if(node -> child[toFind] != NULL){
                count = (count << 1) | 1;
                node = node -> child[toFind];
            // }else if(node -> child[index] != NULL){
            //     count = (count << 1) | 0;
            //     node = node -> child[index];
            }else{
                count = (count << 1) | 0;
                node = node -> child[index];
            }
            i++;
        }
        return count;
    }

    int findMaximumXOR(vector<int>& nums) {
        string word = "";
        for(auto &n : nums){
            bitset<32> bits(n);
            word = bits.to_string();
            insert(word);
        }
        int maxDepth = 0;
        for(auto &n : nums){
            bitset<32> bits(n);
            word = bits.to_string();
            maxDepth = max(maxDepth, search(word));
        }
        return maxDepth;
    }
};
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