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OI-codes/AcWing/143/143.cpp

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#include <bits/stdc++.h>
using namespace std;
int n, a[100005], ans;
struct node {
int val;
node* next[2];
~node() {
for (auto i : next) {
delete i;
}
}
};
void insert(node* root, int x, int b) {
if (!x) {
root->val++;
return;
}
if (root->next[(x >> b) & 1] == nullptr) root->next[(x >> b) & 1] = new node();
insert(root->next[(x >> b) & 1], x - (((x >> b) & 1) << b), b - 1);
}
int search(node* root, int x) {
int res = 0;
node* p = root;
for (int i = 30; i >= 0; i--) {
if (p == nullptr) break;
if (p->next[!((x >> i) & 1)] != nullptr) {
res += 1 << i;
p = p->next[!((x >> i) & 1)];
} else {
p = p->next[(x >> i) & 1];
}
}
return res;
}
int main() {
node* root = new node();
cin >> n;
for (int i = 0; i < n; i++) {
cin >> a[i];
insert(root, a[i], 30);
}
for (int i = 0; i < n; i++) {
ans = max(ans, search(root, a[i]));
}
cout << ans << endl;
delete root;
return 0;
}