<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{
        char ch;
        bool isLast;
        vector<Node*> vec;

        Node(char ch)
        {
            this->ch = ch;
            isLast = false;
            vec = vector<Node*>(2, nullptr);
        }
    };

    class Trie{

        public:
        Node* root;

        Trie()
        {
            root = new Node('\0');
        }

        void insert(int num)
        {
            Node* cur = root;
            for(int i = 31 ; i>=0 ; i--)
            {
                int temp = num >> i;
                if(temp & 1)
                {
                    if(!cur->vec[1])
                        cur->vec[1] = new Node('1');
                    cur = cur->vec[1];
                }
                else
                {
                    if(!cur->vec[0])
                        cur->vec[0] = new Node('0');
                    cur = cur->vec[0];
                } 
            }
        }

        int findMaxXor(int numb)
        {
            if(!root->vec[0] && !root->vec[1])
            {
                return -1;
            }

            Node* cur = root;
            std::string str = "";
            for(int i = 31 ; i >=0 ; i--)
            {
                int temp = numb >> i;
                if(temp&1)
                {
                    if(cur->vec[0])
                    {
                        str.push_back('0');
                        cur = cur->vec[0];
                    }
                    else
                    {
                        str.push_back('1');
                        cur = cur->vec[1];
                    }  
                }
                else
                {
                    if(cur->vec[1])
                    {
                        str.push_back('1');
                        cur = cur->vec[1];
                    }
                    else
                    {
                        str.push_back('0');
                        cur = cur->vec[0];
                    }

                }
            }
            
            int ans = 0;

            //std::cout << str << std::endl;

            for(int i = 0 ; i < str.size() ; i++)
            {
                if(str[i] == '1')
                {
                    ans = ans << 1 | 1;
                }
                else
                {
                    ans = ans << 1;
                }
            }

            //cout << ans << endl;

            return numb ^ ans;
        }

    };

static bool compare(pair<int, vector<int>> &p1, pair<int, vector<int>> &p2)
{
    return p1.second[1] < p2.second[1];
}

class Solution {
public:
    vector<int> maximizeXor(vector<int>& nums, vector<vector<int>>& queries) {
        
        sort(nums.begin() , nums.end());

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

        vector<pair<int, vector<int>>> vec;

        for(int i = 0 ; i < queries.size(); i++)
        {
            vec.push_back({i, queries[i]});
        }

        sort(vec.begin(), vec.end(), compare);

        int idx = 0;

        vector<int> ans(queries.size());

        Trie t;

        for(int i = 0 ; i < vec.size() ; i++)
        {
            while(idx < nums.size())
            {
                if(idx < nums.size() && nums[idx] <= vec[i].second[1])
                {
                    t.insert(nums[idx]);
                    idx++;
                }
                else
                {
                    break;
                }
            }

            ans[vec[i].first] = t.findMaxXor(vec[i].second[0]);

        }

        return ans;

    }
};
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