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https://git.sb/baoshuo/OI-codes.git
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68 lines
1.3 KiB
C++
68 lines
1.3 KiB
C++
#include <iostream>
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#include <algorithm>
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#include <ctime>
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#include <random>
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#include <unordered_map>
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#include <vector>
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using std::cin;
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using std::cout;
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const char endl = '\n';
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const int N = 1e5 + 5;
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int n;
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long long w[N], ans;
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std::mt19937 rng(std::random_device{}());
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int random(int l, int r) {
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return std::uniform_int_distribution<int>(l, r)(rng);
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}
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int main() {
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std::ios::sync_with_stdio(false);
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cin.tie(nullptr);
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cin >> n;
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for (int i = 1; i <= n; i++) {
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cin >> w[i];
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}
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while (clock() <= 0.6 * CLOCKS_PER_SEC) {
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int p = random(1, n);
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std::unordered_map<long long, int> cnt;
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std::vector<long long> v;
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for (int i = 1; i <= n; i++) {
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cnt[std::__gcd(w[i], w[p])]++;
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}
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for (int i = 1; i <= w[p] / i; i++) {
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if (w[p] % i == 0) {
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v.push_back(i);
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if ((w[p] / i) != i) v.push_back(w[p] / i);
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}
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}
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for (long long x : v) {
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int sum = 0;
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for (long long y : v) {
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if (y % x == 0) {
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sum += cnt[y];
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}
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}
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if (sum >= (n + 1) / 2) {
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ans = std::max(ans, x);
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}
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}
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}
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cout << ans << endl;
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return 0;
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}
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