Submission #944287

#	Time	Username	Problem	Language	Result	Execution time	Memory
944287		vjudge1	Dynamic Diameter (CEOI19_diameter)	C++17	11 / 100	5041 ms	24216 KiB

diameter

#include <bits/stdc++.h>
using namespace std;
 
#define int long long
#define pb push_back
#define ff first
#define ss second
#define all(v) v.begin(), v.end()
#define rall(v) v.rbegin(), v.rend()
#define sz(v) (int)v.size()
 
const int INF = 1e18;
const int mod = 998244353;
const int N = 1e5+5;
vector<int> g[N];
map<pair<int,int>,int> w;

void solve(){
	int n, qr, maxw;
	cin >> n >> qr >> maxw;
	vector<pair<int,int> > edges;
	for(int i = 1; i < n; i++){
		int u, v, iw;
		cin >> u >> v >> iw;
		g[u].pb(v);
		g[v].pb(u);
		w[{u, v}] = iw;
		w[{v, u}] = iw;
		edges.pb({u, v});
	}
	int last = 0;
	while(qr--){
		int ind, val;
		cin >> ind >> val;
		ind = (ind + last) % (n - 1);
		val = (val + last) % maxw;
		auto [x, y] = edges[ind];
		w[{x, y}] = val;
		w[{y, x}] = val;
		
		vector<int> dis(n + 1, INF);
		dis[1] = 0;
		priority_queue<pair<int,int>, vector<pair<int,int> >, greater<pair<int,int> > > q;
		q.push({0, 1});
		while(!q.empty()){
			auto [disv, v] = q.top();
			q.pop();
			
			if(disv > dis[v]) continue;
			
			for(auto to : g[v]){
				if(dis[v] + w[{v, to}] < dis[to]){
					dis[to] = dis[v] + w[{v, to}];
					q.push({dis[to], to});
				}
			}
		}
		
		dis[0] = 0;
		int mx = max_element(all(dis)) - dis.begin();
		dis = vector<int>(n + 1, INF);
		dis[mx] = 0;
		q.push({0, mx});
		while(!q.empty()){
			auto [disv, v] = q.top();
			q.pop();
			
			if(disv > dis[v]) continue;
			
			for(auto to : g[v]){
				if(dis[v] + w[{v, to}] < dis[to]){
					dis[to] = dis[v] + w[{v, to}];
					q.push({dis[to], to});
				}
			}
		}
		
		dis[0] = 0;
		last = *max_element(all(dis));
		cout << last << '\n';
	}
}

main(){
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	
	int tt = 1;
	//cin >> tt;
	while (tt--) {
		solve();
	}
}

Compilation message (stderr)

diameter.cpp:84:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   84 | main(){
      | ^~~~

• Subtask 1: 11 / 11
• Subtask 2: 0 / 13
• Subtask 3: 0 / 7
• Subtask 4: 0 / 18
• Subtask 5: 0 / 24
• Subtask 6: 0 / 27