<p>You are given an array <code>nums</code> consisting of non-negative integers. You are also given a <code>queries</code> array, where <code>queries[i] = [x<sub>i</sub>, m<sub>i</sub>]</code>.</p>

<p>The answer to the <code>i<sup>th</sup></code> query is the maximum bitwise <code>XOR</code> value of <code>x<sub>i</sub></code> and any element of <code>nums</code> that does not exceed <code>m<sub>i</sub></code>. In other words, the answer is <code>max(nums[j] XOR x<sub>i</sub>)</code> for all <code>j</code> such that <code>nums[j] &lt;= m<sub>i</sub></code>. If all elements in <code>nums</code> are larger than <code>m<sub>i</sub></code>, then the answer is <code>-1</code>.</p>

<p>Return <em>an integer array </em><code>answer</code><em> where </em><code>answer.length == queries.length</code><em> and </em><code>answer[i]</code><em> is the answer to the </em><code>i<sup>th</sup></code><em> query.</em></p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> nums = [0,1,2,3,4], queries = [[3,1],[1,3],[5,6]]
<strong>Output:</strong> [3,3,7]
<strong>Explanation:</strong>
1) 0 and 1 are the only two integers not greater than 1. 0 XOR 3 = 3 and 1 XOR 3 = 2. The larger of the two is 3.
2) 1 XOR 2 = 3.
3) 5 XOR 2 = 7.
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> nums = [5,2,4,6,6,3], queries = [[12,4],[8,1],[6,3]]
<strong>Output:</strong> [15,-1,5]
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= nums.length, queries.length &lt;= 10<sup>5</sup></code></li>
	<li><code>queries[i].length == 2</code></li>
	<li><code>0 &lt;= nums[j], x<sub>i</sub>, m<sub>i</sub> &lt;= 10<sup>9</sup></code></li>
</ul>

class Node{
    vector<Node*> link = vector<Node*> (2, NULL);
public:
    bool isEmpty(){
        return (link[0] == link[1] && link[1] == NULL);
    }
    bool linkPresent(int bit){
        return link[bit] != NULL;
    }
    void put(int bit, Node* node){
        link[bit] = node;
    }
    Node* get(int bit){
        return link[bit];
    }
};
class Trie{
    Node* root;
public:
    Trie(){
        root = new Node();
    }
    void insert(int num){
        Node* node = root;

        for(int i = 31; i>-1; i--){
            int bit = (num>>i) & 1;

            if(!node->linkPresent(bit)){
                node->put(bit, new Node());
            }
            node = node->get(bit);
        }
    }
    int getMax(int num){
        int maxx = 0;
        Node* node = root;
        if(node->isEmpty()) return -1;
        for(int i = 31; i>-1; i--){
            int bit = (num>>i) & 1;

            if(node->linkPresent(1-bit)){
                maxx = maxx | (1<<i);
                node = node->get(1-bit);
            }
            else node = node->get(bit);
        }
        return maxx;
    }
};
class Solution {
public:
    vector<int> maximizeXor(vector<int>& nums, vector<vector<int>>& queries) {
        ios_base::sync_with_stdio(false);
        cin.tie(nullptr);
        cout.tie(nullptr);
        sort(nums.begin(), nums.end());
        // sort(queries.begin(), queries.end(), [](vector<int> a, vector<int> b){
        //     return a[1] < b[1];
        // });

        priority_queue<pair<int,int>, vector<pair<int,int>>, greater<pair<int,int>>> pq;

        for(int i =0; i<queries.size(); i++){
            pq.push({queries[i][1], i});
        }

        Trie* trie = new Trie();
        vector<int>ans (queries.size(), -1);

        int i = 0;
        while(pq.empty()== false){
            int ind = pq.top().second;
            pq.pop();

            while(i<nums.size() && nums[i] <= queries[ind][1]){
                trie->insert(nums[i++]);
            }
            
            ans[ind] = trie->getMax(queries[ind][0]);
        }

        return ans;
    }
};
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