Submission #943951

#	Time	Username	Problem	Language	Result	Execution time	Memory
943951		vjudge1	Dynamic Diameter (CEOI19_diameter)	C++17	18 / 100	5022 ms	29956 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;
int p[N], d[N], dp[N], _res[N];
map<pair<int,int>,int> w;
vector<int> g[N], order;
multiset<int> ans;

void dfs(int v){
	for(auto to : g[v]){
		if(to != p[v]){
			p[to] = v;
			d[to] = d[v] + 1;
			dfs(to);
		}
	}
	order.pb(v);
}

void solve(){
	int n, q, wmax;
	cin >> n >> q >> wmax;
	vector<pair<int,int> > edges(n + 1);
	for(int i = 0; i < n - 1; i++){
		int u, v, wi;
		cin >> u >> v >> wi;
		g[u].pb(v);
		g[v].pb(u);
		w[{u, v}] = wi;
		w[{v, u}] = wi;
		edges[i] = {u, v};
	}
	dfs(1);
	for(int v : order){
		for(auto to : g[v]){
			if(to != p[v]){
				dp[v] = max(dp[v], dp[to] + w[{v, to}]);
				_res[v] += dp[to] + w[{v, to}];
			}
		}
		
		ans.insert(_res[v]);
	}
	int last = 0;
	while(q--){
		int ind, val;
		cin >> ind >> val;
		ind = (ind + last) % (n - 1);
		val = (val + last) % wmax;
		auto [u, v] = edges[ind];
		if(d[u] < d[v]) swap(u, v);
		w[{u, v}] = val;
		w[{v, u}] = val;
		while(v){
			int res = 0;
			dp[v] = 0;
			for(auto to : g[v]){
				if(to != p[v]){
					dp[v] = max(dp[v], dp[to] + w[{v, to}]);
					res += dp[to] + w[{v, to}];
				}
			}
			
			ans.erase(ans.find(_res[v]));
			ans.insert(res);
			_res[v] = res;
			
			v = p[v];
		}
		
		last = *ans.rbegin();
		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:87:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   87 | main(){
      | ^~~~

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