<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 TrieNode{
    public:
    vector<TrieNode*> child;
    int val;
    TrieNode()
    {
        child = vector<TrieNode*>(2, NULL);
        val = -1;
    }
};
bool comp(vector<int> &a, vector<int> &b)
{
    return a[1] < b[1];
}
class Solution {
public:
    TrieNode *head;
    void insert(int x)
    {
        bitset<32> bs(x);
        auto node = head;
        for(int i=31; i>=0; i--)
        {
            int cur = bs[i];
            if(!node->child[cur])
            {
                auto cn = new TrieNode();
                cn->val = cur;
                node->child[cur] = cn;
            }
            node = node->child[cur];
        }
    }
    vector<int> maximizeXor(vector<int>& nums, vector<vector<int>>& queries) {
        sort(nums.begin(), nums.end());
        head = new TrieNode();
        map<vector<int>, int> m;
        vector<vector<int>> v = queries;
        sort(v.begin(), v.end(), comp);
        int i = 0;
        for(auto q: v)
        {
            while(i<nums.size() && nums[i] <= q[1])
            {
                insert(nums[i]);
                i++;
            }
            if(i == 0)
                m[q] = -1;
            else
                m[q] = maxxor(q[0]);   
        }
        vector<int> ans;
        for(auto q: queries)
        {
            ans.push_back(m[q]);
        }
        return ans;
    }
    int maxxor(int x)
    {
        bitset<32> bs(x);
        int ans = 0;
        auto node = head;
        for(int i=31; i>=0; i--)
        {
            if(node->child[!bs[i]])
            {
                ans += (1<<i);
                node = node->child[!bs[i]];
            }
            else
                node = node->child[bs[i]];
        }
        return ans;
    }
};
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