<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>

struct Node{
    Node *links[2];

    Node(){
        for(int i=0;i<2;i++){
            links[i] = NULL;
        }
    }
    void set(int i,Node *node){
        links[i] = node;
    }
    bool containsKey(int i){
        return links[i] != NULL;
    }
    Node *get(int i){
        return links[i];
    }
};

class Trie{
    Node *root;
    public:
    Trie(){
        root = new Node();
    }

    int getBit(int x,int pos){
        return (x & (1<< pos)) != 0;
    }

    int setBit(int x,int pos){
        return x | (1<<pos);
    }

     void insertInteger(int x){
         Node *node = root;
         for(int i=31;i>=0;i--){
             int bit = getBit(x,i);
             if(!node->containsKey(bit)){
                 node->set(bit, new Node());
             }
             node = node->get(bit);
         }
     }

     int getMax(int x){
         int maxXor = 0;
         Node *node = root;
         for(int i=31;i>=0;i--){
             int oppositeBit = !getBit(x, i);
             if(node->containsKey(oppositeBit)){
                 maxXor = setBit(maxXor, i);
                 node = node->get(oppositeBit);
             }
             else{
                 node = node->get(!oppositeBit);
             }
         }
         return maxXor;
     }

      void recDelete(Node *node){
        if(node != NULL){
            for(int i=0;i<2;i++){
                recDelete(node->get(i));
            }
            delete node;
        }
      }

     ~Trie(){
        //   recDelete(root);
     }

};

class Solution {
public:

    static bool comp(vector<int> v1,vector<int> v2){
        return v1[1] < v2[1];
    }

    vector<int> maximizeXor(vector<int>& nums, vector<vector<int>>& queries) {
        int qsize = queries.size();
        int n = nums.size();
        vector<int> ans(qsize,-1);
        Trie tr;

        // x,m,i ==> i index in query
        vector<vector<int>> sortedQueries;

        for(int i=0;i<qsize;i++){
            sortedQueries.push_back({queries[i][0],queries[i][1],i});
        }

        sort(sortedQueries.begin(),sortedQueries.end(),comp);
        sort(nums.begin(),nums.end());

        int ind = 0;

        for(int j=0;j<qsize;j++){
            int x = sortedQueries[j][0];
            int m = sortedQueries[j][1];
            int qIndex = sortedQueries[j][2];

            while(ind < n && nums[ind] <= m){
                tr.insertInteger(nums[ind]);
                ind++;
            }
            if(ind == 0) ans[qIndex] = -1;
            else ans[qIndex] = tr.getMax(x);

        }
        return ans;
    }
};
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