<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* link[2];
    int flag = false;
    int val = -1;
    bool containsKey(int ch)
    {
        return link[ch] != NULL;
    }
    void put(int ch, Node* node)
    {
        link[ch] = node;
    }
    Node* get(int ch)
    {
        return link[ch];
    }
};
class Trie{
    public:
    Node* root;
    Trie(){
        root = new Node();
    }
    void insert(vector<int>& bits, int val)
    {
        Node* node = root;
        for(int i=0;i<32;i++)
        {
            if(!node->containsKey(bits[i]))
            {
                node->put(bits[i], new Node());
            }
            node = node->get(bits[i]);
        }
        node->val = val;
        node->flag = true;
    }
    int getxor(vector<int>& bits, int num)
    {
        Node* node = root;
        for(int i=0;i<32;i++)
        {
            if(node->containsKey((bits[i]+1)%2))
            {
                node = node->get((bits[i]+1)%2);
            }
            else if(node->containsKey(bits[i]))
                node = node->get(bits[i]);
        }
        // cout <<"xor: " << num << " " << node->val << endl;
        return num ^ node->val;
    }
};
class Solution {
public:
    vector<int> convert(int num)
    {
        vector<int> bits(32,0);
        for(int i=31;i>=0;i--)
        {
            bits[i] = (num & (1 << (31-i)) ? 1 : 0);
        }
        // cout << "num: " << num << " ";
        // for(auto x : bits)
        //     cout << x << " ";
        //     cout << endl;
        return bits;
    }
    vector<int> maximizeXor(vector<int>& nums, vector<vector<int>>& queries) {
        int n = nums.size();
        sort(nums.begin(), nums.end());
        for(int i=0;i<queries.size();i++)
        {
            queries[i].push_back(i);
        }
        sort(queries.begin(), queries.end(), [](vector<int>& a, vector<int>& b){
            return a[1] < b[1];
        });
        // for(auto x : queries)
        // {
        //     cout << x[0] << " "<<x[1] <<" "<< x[2] << endl;
        // }
        Trie* t = new Trie();
        int insert_index = 0;
        vector<int> ans(queries.size(),-1);
        for(int i=0;i<queries.size();i++)
        {
            int num = queries[i][0];
            int limit = queries[i][1];
            int qindex = queries[i][2];
            while(insert_index < n && limit >= nums[insert_index])
            {
                auto x = convert(nums[insert_index]);
                t->insert(x, nums[insert_index]);
                insert_index++;
            }
            // cout << insert_index << " ";
            if(insert_index > 0)
            {
                auto x = convert(num);
                int res = t->getxor(x, num);
                ans[qindex] = res;
            }
        }
        return ans;
    }
};
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