157 lines
3.1 KiB
C++
157 lines
3.1 KiB
C++
/* Problem URL: https://codeforces.com/edu/course/2/lesson/7/2/practice/contest/289391/problem/F */
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#include <bits/stdc++.h>
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#include <ext/pb_ds/assoc_container.hpp>
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#include <ext/pb_ds/tree_policy.hpp>
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using namespace std;
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using namespace __gnu_pbds;
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template <class T, class comp = less<>>
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using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
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#define V vector
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#define rmin(a, b) a = min(a, b)
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#define rmax(a, b) a = max(a, b)
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#define rep(i, lim) for (int i = 0; i < (lim); i++)
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#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
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#define repv(i, v) for (auto &i : (v))
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#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
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#define sortv(v) sort(v.begin(), v.end())
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#define all(v) (v).begin(), (v).end()
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using vi = vector<int>;
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using vvi = vector<vi>;
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using vvvi = vector<vvi>;
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using vvvvi = vector<vvvi>;
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using ll = long long;
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using vl = vector<ll>;
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using vvl = vector<vl>;
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using vvvl = vector<vvl>;
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using vvvvl = vector<vvvl>;
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template<class v>
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auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
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os << vec[0];
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for (size_t i = 1; i < vec.size(); i++) {
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os << ' ' << vec[i];
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}
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os << '\n';
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return os;
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}
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template<class v>
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auto operator>>(istream &is, vector<v> &vec)->istream& {
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for (auto &i : vec) {
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is >> i;
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}
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return is;
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}
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template<class v>
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auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
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for (auto &i : vec) {
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os << i[0];
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for (size_t j = 1; j < i.size(); j++) {
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os << ' ' << i[j];
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}
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os << '\n';
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}
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return os;
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}
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template<class v>
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auto operator>>(istream &is, vector<vector<v>> &vec)->istream& {
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for (auto &i : vec) {
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for (auto &j : i) {
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is >> j;
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}
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}
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return is;
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}
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int main()
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{
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ios::sync_with_stdio(false);
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cin.tie(nullptr);
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int n, m;
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cin >> n >> m;
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vvi graph(n);
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V<tuple<ll, int, int>> edges(m);
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for (auto &[c, u, v] : edges) {
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cin >> u >> v >> c;
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u--, v--;
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}
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vi dsu(n);
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function<int(int)> find_p = [&](int i) {
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if (dsu[i] == i) {
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return i;
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}
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return dsu[i] = find_p(dsu[i]);
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};
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auto join = [&](int a, int b) {
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a = find_p(a);
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b = find_p(b);
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dsu[b] = a;
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return a != b;
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};
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sortv(edges);
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ll oo = INT64_MAX >> 1;
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auto getans = [&]() {
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ll ans = oo;
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rep(i, m) {
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rep(j, n) {
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dsu[j] = j;
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}
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ll minimal = oo;
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ll maximal = -oo;
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int num = n - 1;
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int j = i;
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while (j < m && num > 0) {
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auto [c, u, v] = edges[j];
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if (join(u, v)) {
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rmin(minimal, c);
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rmax(maximal, c);
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num--;
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}
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j++;
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}
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if (num > 0) {
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return ans;
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}
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rmin(ans, abs(maximal - minimal));
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}
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return ans;
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};
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ll ans = getans();
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if (ans == oo) {
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cout << "NO\n";
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return 0;
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}
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cout << "YES\n" << ans << '\n';
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}
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