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integer_trie_template.cpp
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integer_trie_template.cpp
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#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
int getRand(int l, int r)
{
uniform_int_distribution<int> uid(l, r);
return uid(rng);
}
// typedefs
typedef tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update> ordered_set;
typedef long long ll;
// debug section
// print section
void print()
{
cout << endl;
}
template <typename T1, typename... T2>
void print(T1 var1, T2... var2)
{
cout << var1 << ' ';
print(var2...);
}
// vector operator overload - input
template <typename T>
istream &operator>>(istream &os, vector<T> &v)
{
for (int i = 0; i < v.size(); ++i)
{
os >> v[i];
}
return os;
}
// vector operator overload - output
template <typename T>
ostream &operator<<(ostream &os, const vector<T> &v)
{
for (int i = 0; i < v.size(); ++i)
{
os << v[i];
if (i != v.size() - 1)
os << ' ';
}
return os;
}
struct Node
{
Node *links[2];
// checks if the reference trie is present or not
bool containsKey(int bit)
{
return (links[bit] != NULL);
}
// creating reference trie
void put(int bit, Node *node)
{
links[bit] = node;
}
// to get the next node for traversal
Node *get(int bit)
{
return links[bit];
}
};
class Trie
{
Node *root;
public:
Trie()
{
root = new Node();
}
void insert(int num)
{
Node *node = root;
for (int i = 31; i >= 0; i--)
{
int bit = (num >> i) & 1;
if (!node->containsKey(bit))
node->put(bit, new Node());
node = node->get(bit);
}
}
int findMaxXorVia(int num)
{
Node *node = root;
int maxNum = 0;
for (int i = 31; i >= 0; i--)
{
int bit = (num >> i) & 1;
if (node->containsKey(!bit))
{
maxNum = maxNum | (1 << i);
node = node->get(!bit);
}
else
{
node = node->get(bit);
}
}
return maxNum;
}
};
int maxXOR(int n, int m, vector<int> &arr1, vector<int> &arr2)
{
Trie *t = new Trie();
for (auto i : arr1)
t->insert(i);
int ans = 0;
for (auto i : arr2)
ans = max(ans, t->findMaxXorVia(i));
return ans;
}
vector<int> maxXorQueries(vector<int> &arr, vector<vector<int>> &queries)
{
// Write your coode here.
int q = queries.size();
for (int i = 0; i < q; i++)
queries[i].push_back(i);
sort(queries.begin(), queries.end(), [&](vector<int> &a, vector<int> &b) -> bool
{ return a[1] < b[1]; });
sort(arr.begin(), arr.end());
Trie *t = new Trie();
vector<int> ans(q);
int itr = 0;
for (int i = 0; i < q; i++)
{
int x = queries[i][0];
int less = queries[i][1];
int index = queries[i][2];
while (itr < arr.size() && arr[itr] <= less)
t->insert(arr[itr++]);
if (itr == 0)
ans[index] = -1;
else
ans[index] = t->findMaxXorVia(x);
}
return ans;
}
int main()
{
int t;
cin >> t;
while (t--)
{
int n, q;
cin >> n >> q;
vector<int> v(n);
cin >> v;
vector<vector<int>> qr;
for (int i = 0; i < q; i++)
{
int x, a;
cin >> x >> a;
qr.push_back({x, a});
}
cout << maxXorQueries(v, qr) << endl;
}
return 0;
}