<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 Solution {
public:
    struct Node {
        vector<Node*> v = vector<Node*>(2, NULL);
        int number = -1;
        int minn = INT_MAX;
    };
    class Trie {
        public: 
            Node* root;
            Trie() {
                root=new Node();
            }
            void insert(int num) {
                Node* temp = root;
                for(int i=30;i>=0;i--) {
                    int x = (1<<i & num) ? 1 : 0;
                    if(temp->v[x] == NULL) temp->v[x] = new Node();
                    temp = temp->v[x];
                    temp->minn = min(temp->minn, num);
                }
                temp->number = num;
            }
    };
    void f(int num, int thres, Node* temp, bool isAlreadyLess, int place, int *maxx) {
        // cout<<num<<" "<<place<<" "<<thres<<endl;
        if(place == -1) {
            *maxx = max(*maxx, num^temp->number);
            return;
        }
        int x = (1<<place & num) ? 1 : 0;
        int y = (1<<place & thres) ? 1 : 0;
        // cout<<x<<" "<<y<<endl;
        if(x == 1) {
            if(temp->v[0] != NULL) f(num, thres, temp->v[0], isAlreadyLess||(y==1), place-1, maxx);
            else {
                if(!isAlreadyLess && y==0) return;
                else f(num, thres, temp->v[1], isAlreadyLess, place-1, maxx);
            }
        } else {
            if(temp->v[1] != NULL) {
                if(isAlreadyLess || y==1) {
                    f(num, thres, temp->v[1], isAlreadyLess, place-1, maxx);
                    if(temp->v[0]!=NULL && temp->minn<=thres && (*maxx == -1)) f(num, thres, temp->v[0], isAlreadyLess||(y==1), place-1, maxx);
                }
                else {
                    if(temp->v[0]!=NULL && temp->minn<=thres) f(num, thres, temp->v[0], isAlreadyLess||(y==1), place-1, maxx);
                }
            } else f(num, thres, temp->v[0], isAlreadyLess||(y==1), place-1, maxx);
        }
    }
    vector<int> maximizeXor(vector<int>& nums, vector<vector<int>>& queries) {
        sort(nums.begin(), nums.end());
        Trie* t = new Trie();
        for(int i=0;i<nums.size();i++) t->insert(nums[i]);
        vector<int> ans(queries.size(), -1);
        for(int i=0;i<queries.size();i++) {
            int num = queries[i][0];
            int thres = queries[i][1];
            int maxx = -1;
            f(num, thres, t->root, false, 30, &maxx);
            ans[i] = maxx;
        }
        return ans;
    }
};
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