<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 Node{
    Node* child[2];
    int cnt;
    vector<int> wend;

    Node(){
        child[0] = NULL;
        child[1] = NULL;
        
        cnt = 0;     
    }
};
class Trie{
public:
    Node* root;

    Trie(){
        root = new Node;
    }

    void insert(int n, int ln){
        Node* curr = root;
        for(int i=(ln-1); i>=0; i--){
            curr->cnt++;
            int x = (n&(1<<i)) ? 1 : 0;

            if(curr->child[x] == NULL){
                curr->child[x] = new Node;
            }

            curr=curr->child[x];
        }
        curr->wend.push_back(n);
    }

    int getXorMax(int x, int ln){
        Node* curr = root;
        for(int i=(ln-1); i>=0; i--){
            curr->cnt++;
            int bit = (x&(1<<i)) ? 1 : 0;

            if(curr->child[0] == NULL){
                curr = curr->child[1];
            }
            else if(curr->child[1] == NULL){
                curr = curr->child[0];
            }
            else{
                if(!bit){
                    curr = curr->child[1];
                }
                if(bit){
                    curr = curr->child[0];
                }
            }
        }

        return curr->wend[0];
    }
};
class Solution {
public:
    int findMaximumXOR(vector<int>& nums) {
        int n=nums.size();

        int ln = 31;
        Trie trie;
        trie.insert(nums[0], ln);

        int ans = 0;
        for(int i=1; i<n; i++){
            int x = nums[i];
            int y = trie.getXorMax(x, ln);

            ans = max(ans, x^y);
            trie.insert(nums[i], ln);
        }

        return ans;
    }
};
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