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Submission #676681

# Submission time Handle Problem Language Result Execution time Memory
676681 2022-12-31T17:33:16 Z QwertyPi Islands (IOI08_islands) C++14
80 / 100
 688 ms 131072 KB 
#include <bits/stdc++.h>
#define fi first
#define se second
using namespace std;

const int N = 1e6 + 11;
vector<pair<int, int>> G[N];
int p[N], w[N], tin[N], t = 0;
long long dp[N];
bool vis[N], cyc[N];
struct edge{
	int u, v, w;
};

vector<edge> extra;
void dfs(int id, int v, int pa = -1){
	vis[v] = true; tin[v] = ++t;
	for(auto i : G[v]){
		if(!vis[i.fi]){
			p[i.fi] = v;
			dfs(id, i.fi, v);
			w[i.fi] = i.se;
		}else if(i.fi != pa){
			extra[id] = {v, i.fi, i.se};
		}
	}
}

bool is_anc(int u, int v){
	return tin[u] <= tin[v];
}

long long dfs_dp(int id, int v, int pa = -1){
	vector<long long> dis;
	long long ans = 0;
	for(auto i : G[v]){
		if(!cyc[i.fi] && i.fi != pa){
			long long r = dfs_dp(id, i.fi, v);
			ans = max(ans, r);
			dis.push_back(dp[i.fi] + i.se);
		}
	}
	sort(dis.begin(), dis.end());
	if(dis.size() >= 2) ans = max(ans, dis.back() + dis[dis.size() - 2]);
	if(dis.size()) dp[v] = dis.back(), ans = max(ans, dis.back());
	return ans;
}

long long solve(int id, vector<long long>& DP, vector<int>& W){
	int n = W.size();
	vector<long long> S(n * 2 + 1);
	S[0] = 0;
	for(int i = 0; i < n; i++){
		S[i + 1] = S[i] + W[i];
	}
	for(int i = 0; i < n; i++){
		S[n + i + 1] = S[n + i] + W[i];
	}
	priority_queue<long long> pq, _pq;
	for(int i = 0; i < n; i++){
		pq.push(S[i] + DP[i]);
	}
	long long ans = 0;
	for(int i = 0; i < n; i++){
		_pq.push(S[i] + DP[i]);
		while(pq.size() && _pq.size() && pq.top() == _pq.top()) pq.pop(), _pq.pop();
		ans = max(ans, DP[i] - S[i] + pq.top());
		pq.push(S[i + n] + DP[i]);
	}
	return ans;
}

int32_t main(){
	cin.tie(0); cout.tie(0)->sync_with_stdio(false);
	int n; cin >> n;
	for(int i = 1; i <= n; i++){
		int v, _w; cin >> v >> _w;
		G[i].push_back({v, _w});
		G[v].push_back({i, _w});
	}
	for(int i = 1; i <= n; i++){
		G[i].shrink_to_fit();
	}
	
	vector<int> roots;
	for(int i = 1; i <= n; i++){
		if(!vis[i]){
			extra.resize(extra.size() + 1);
			dfs(roots.size(), i);
			roots.push_back(i);
		}
	}
	
	int CC = roots.size();
	long long ans = 0;
	for(int i = 0; i < CC; i++){
		vector<pair<int, int>> cyc_L, cyc_R;
		int x = extra[i].u, y = extra[i].v;
		vector<int> cyc_v;
		while(!is_anc(x, y)){
			cyc_v.push_back(x);
			cyc[x] = true;
			cyc_L.push_back({x, w[x]});
			x = p[x];
		}
		while(!is_anc(y, x)){
			cyc_v.push_back(y);
			cyc[y] = true;
			cyc_R.push_back({y, w[y]});
			y = p[y];
		}
		int l = x;
		cyc_v.push_back(l);
		cyc[l] = true;
		long long rans = 0;
		for(auto v : cyc_v){
			rans = max(rans, dfs_dp(i, v));
		}
		cyc_v.resize(0); 
		vector<int> W; vector<long long> DP;
		for(auto i : cyc_L){
			DP.push_back(dp[i.fi]);
			W.push_back(i.se);
		}
		DP.push_back(dp[l]);
		for(int i = (int) cyc_R.size() - 1; i >= 0; i--){
			DP.push_back(dp[cyc_R[i].fi]);
			W.push_back(cyc_R[i].se); 
		}
		cyc_L.resize(0); cyc_R.resize(0);
		W.push_back(extra[i].w);
		rans = max(rans, solve(i, DP, W));
		ans += rans;
	}
	cout << ans << endl;
}

Subtask #1
33.0 / 33.0

# Verdict Execution time Memory Grader output
1 Correct 11 ms 23764 KB Output is correct
2 Correct 12 ms 23800 KB Output is correct
3 Correct 12 ms 23880 KB Output is correct
4 Correct 13 ms 23764 KB Output is correct
5 Correct 12 ms 23788 KB Output is correct
6 Correct 11 ms 23764 KB Output is correct
7 Correct 13 ms 23764 KB Output is correct
8 Correct 14 ms 23764 KB Output is correct
9 Correct 12 ms 23768 KB Output is correct
10 Correct 14 ms 23764 KB Output is correct
11 Correct 13 ms 23756 KB Output is correct

Subtask #2
3.0 / 3.0

# Verdict Execution time Memory Grader output
1 Correct 13 ms 23912 KB Output is correct
2 Correct 12 ms 23892 KB Output is correct

Subtask #3
4.0 / 4.0

# Verdict Execution time Memory Grader output
1 Correct 12 ms 23888 KB Output is correct
2 Correct 14 ms 24404 KB Output is correct

Subtask #4
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 18 ms 25204 KB Output is correct
2 Correct 27 ms 28280 KB Output is correct
3 Correct 21 ms 25172 KB Output is correct
4 Correct 18 ms 24456 KB Output is correct

Subtask #5
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 34 ms 30152 KB Output is correct
2 Correct 50 ms 32308 KB Output is correct

Subtask #6
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 92 ms 38892 KB Output is correct
2 Correct 103 ms 47988 KB Output is correct
3 Correct 129 ms 62836 KB Output is correct

Subtask #7
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 155 ms 48172 KB Output is correct
2 Correct 207 ms 84024 KB Output is correct
3 Correct 247 ms 90784 KB Output is correct
4 Correct 296 ms 120972 KB Output is correct

Subtask #8
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 346 ms 91804 KB Output is correct
2 Runtime error 688 ms 131072 KB Execution killed with signal 9
3 Halted 0 ms 0 KB -

Subtask #9
0 / 10.0

# Verdict Execution time Memory Grader output
1 Runtime error 305 ms 131072 KB Execution killed with signal 9
2 Halted 0 ms 0 KB -