<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 TrieNode {
public:
    int val;
    TrieNode* child[2];
    bool isTerminal;
    TrieNode(int val) {
        this->val = val;
        child[0] = child[1] = NULL;
        isTerminal = false;
    }
};
class Trie {
public:
    TrieNode* root;
    Trie() { root = new TrieNode(-1); }
    void insert(string s) {
        TrieNode* t = root;
        for (int i = 0; i < s.length(); i++) {
            if (t->child[s[i] - '0'] != NULL) {
                t = t->child[s[i] - '0'];
            } else {
                t->child[s[i] - '0'] = new TrieNode(s[i] - '0');
                t = t->child[s[i] - '0'];
            }
        }
        t->isTerminal = true;
    }
    int getmax(string s) {
        TrieNode* t = root;
        int ans = 0, curr = 31;
        for (int i = 0; i < s.length(); i++) {
            int f = 0;
            if (s[i] == '0') {
                f = 1;
            }
            if (t->child[f] != NULL) {
                t = t->child[f];
                ans = (ans | (1 << curr));
            } else if (t->child[1 - f] != NULL) {
                t = t->child[1 - f];
            } else {
                break;
            }
            curr--;
        }
        return ans;
    }
};
class Solution {
public:
    int findMaximumXOR(vector<int>& nums) {
        Trie* t = new Trie();
        int ans =0 ;
        for(int j = 0;j<nums.size();j++){
            string s = "";
            for(int i = 31;i>=0;i--){
                if(((1LL<<i)&nums[j])){
                    s += '1';
                }else{
                    s += '0';
                }
            }
            t->insert(s);
            ans = max(ans,t->getmax(s));
        }
        return ans;
    }
};
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