Submission #1162554

#	Time	Username	Problem	Language	Result	Execution time	Memory
1162554		Dan4Life	Islands (IOI08_islands)	C++20	64 / 100	331 ms	153124 KiB

islands

#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define sz(a) (int)a.size()
using ll = long long;
using ar2 = array<int,2>;
using vi = vector<int>;
const int mxN = (int)1e6+10;
ll n, far;
ar2 nx[mxN];
bitset<mxN> cyc;
vector<ar2> radj[mxN];
ll vis[mxN], pref[mxN];

void dfs(vector<ar2> adj[], int s, int p){
	far=max(far,vis[s]);
	for(auto [u,w] : adj[s]){
		if(u==p or cyc[u]) continue;
		vis[u] = vis[s]+w; dfs(adj,u,s);
	}
}

int main(){
	ios_base::sync_with_stdio(false); cin.tie(0);
	cin >> n; ll ans = 0;
	for(int i = 1; i <= n; i++){
		int x, w; cin >> x >> w; 
		nx[i]={x,w}; radj[x].pb({i,w});
	}
	for(int i = 1; i <= n; i++){
		if(vis[i]) continue;
		int x = i; vi v; v.clear();
		while(!vis[x]) vis[x]=1,v.pb(x),x=nx[x][0];
		for(auto u : v) vis[u]=0; v.clear();
		while(!cyc[x]) cyc[x]=1,v.pb(x),x=nx[x][0];
		for(auto u : v){ far = 0; dfs(radj,u,0); vis[u] = far; }
		int m = sz(v); for(int i = 0; i < m; i++) v.pb(v[i]);
		multiset<ll> S; S.clear(); ll sum = 0; pref[0] = 0;
		for(int i = 0; i < sz(v); i++){
			sum=max(sum,vis[v[i]]);
			pref[i+1]=pref[i]+(ll)nx[v[i]][1];
			S.insert(vis[v[i]]-pref[i]);	
		}
		for(int i = m; i < sz(v); i++){
			S.erase(S.find(vis[v[i-m]]-pref[i-m]));
			sum=max(sum, vis[v[i]]+pref[i]+*prev(end(S))); 
		}
		ans+=sum; for(auto u : v) vis[u]=1;
	}
	cout << ans << "\n";
}

• Subtask 1: 27 / 33
• Subtask 2: 3 / 3
• Subtask 3: 4 / 4
• Subtask 4: 0 / 10
• Subtask 5: 10 / 10
• Subtask 6: 10 / 10
• Subtask 7: 10 / 10
• Subtask 8: 0 / 10
• Subtask 9: 0 / 10