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Submission #396287

# Submission time Handle Problem Language Result Execution time Memory
396287 2021-04-29T16:44:08 Z Berted Islands (IOI08_islands) C++14
90 / 100
 1806 ms 131072 KB 
#include <iostream>
#include <vector>
#include <algorithm>
#include <deque>
#define ll long long
#define pii pair<int, int>
#define pip pair<int, pii>
#define fst first
#define snd second

using namespace std;

const int SZ = 1000000;

int N;
pip edge[2 * SZ + 5]; int szz = 0;
int H[SZ + 5]; vector<int> vis;

vector<pii> cyc;
ll DP[SZ + 5];
deque<pair<ll, int>> dq;

ll M[2], ans = 0;

int DFS1(int u, pii p)
{
	int ret = H[u] + 1;
	vis.push_back(u);

	//cerr << "D1: " << u << " " << H[u] << "\n";
	for (int i = lower_bound(edge, edge + szz, make_pair(u, make_pair(-1, -1))) - edge; i < szz && edge[i].fst == u; i++)
	{
		const pii& v = edge[i].snd;
		if (p == v) {p = {-1, -1}; continue;}
		if (H[v.fst] == -1)
		{
			H[v.fst] = H[u] + 1;
			ret = DFS1(v.fst, {u, v.snd});
		}
		else if (H[v.fst] < H[u]) {ret = H[v.fst];}
		if (ret <= H[u])
		{
			cyc.push_back({u, v.snd});
			break;
		}
	}
	return ret;
}

ll DFS2(int u)
{
	ll ret = 0;
	for (int i = lower_bound(edge, edge + szz, make_pair(u, make_pair(-1, -1))) - edge; i < szz && edge[i].fst == u; i++)
	{
		const pii& v = edge[i].snd;
		if (H[v.fst] == -1)
		{
			H[v.fst] = H[u] + 1;
			ret = max(ret, DFS2(v.fst));
			DP[u] = max(DP[u], DP[v.fst] + v.snd);
		}
	}
	M[0] = 0; M[1] = 0;
	for (int i = lower_bound(edge, edge + szz, make_pair(u, make_pair(-1, -1))) - edge; i < szz && edge[i].fst == u; i++)
	{
		const pii& v = edge[i].snd;
		if (H[v.fst] > H[u])
		{
			if (DP[v.fst] + v.snd > M[0]) {M[1] = M[0]; M[0] = DP[v.fst] + v.snd;}
			else if (DP[v.fst] + v.snd > M[1]) {M[1] = DP[v.fst] + v.snd;}
		}
	}
	return max(ret, M[0] + M[1]);
}

int main()
{
	ios :: sync_with_stdio(0); cin.tie(0); cout.tie(0);
	cin >> N;
	for (int i = 0; i < N; i++)
	{
		int u, c; cin >> u >> c; u--;
		edge[szz++] = {u, {i, c}};
		edge[szz++] = {i, {u, c}};
		H[i] = -1;
	}

	sort(edge, edge + szz);

	for (int k = 0; k < N; k++)
	{
		if (H[k] == -1)
		{
			ll rr = 0; H[k] = 0;
			DFS1(k, {-1, -1});
			for (const auto &u : vis) H[u] = -1;
			vis.clear();
			
			for (const auto &u : cyc) H[u.fst] = 0;
			for (const auto &u : cyc) rr = max(rr, DFS2(u.fst));

			//cerr << k << ": " << rr << " " << cyc.size() << "\n";

			ll s = 0, t = 0;
			for (int i = 1; i < cyc.size(); i++)
			{
				//cerr << "id: " << i << " " << cyc[i].fst << " - " << DP[cyc[i].fst] << "\n";
				s += cyc[i].snd;
				while (dq.size() && dq.back().fst <= s + DP[cyc[i].fst]) 
				{
					//cerr << "Popped\n";
					dq.pop_back();
				}
				//cerr << "Pushed: " << s + DP[cyc[i].fst] << ", " << i << "\n";
				dq.push_back({s + DP[cyc[i].fst], i});
			}
			s += cyc[0].snd;

			for (int i = 0; i < cyc.size(); i++)
			{
				if (dq.front().snd == i) dq.pop_front();
				//cerr << i << " " << " " << cyc[i].fst << " " << dq.front().fst << " " << t << " " << DP[cyc[i].fst] << "\n";
				rr = max(rr, dq.front().fst + t + DP[cyc[i].fst]);
				while (dq.size() && dq.back().fst + t <= s + DP[cyc[i].fst]) {dq.pop_back();}
				dq.push_back({s + DP[cyc[i].fst] - t, i});
				t -= cyc[(i + 1) % cyc.size()].snd;
			}

			dq.clear();
			cyc.clear();

			//cerr << k << ": " << rr << "\n";

			ans += rr;
		}
	}
	
	cout << ans << "\n";
	return 0;
}

Compilation message

islands.cpp: In function 'int main()':
islands.cpp:105:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  105 |    for (int i = 1; i < cyc.size(); i++)
      |                    ~~^~~~~~~~~~~~
islands.cpp:119:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  119 |    for (int i = 0; i < cyc.size(); i++)
      |                    ~~^~~~~~~~~~~~

Subtask #1
33.0 / 33.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 332 KB Output is correct
2 Correct 1 ms 332 KB Output is correct
3 Correct 1 ms 332 KB Output is correct
4 Correct 1 ms 332 KB Output is correct
5 Correct 1 ms 332 KB Output is correct
6 Correct 1 ms 332 KB Output is correct
7 Correct 1 ms 336 KB Output is correct
8 Correct 1 ms 332 KB Output is correct
9 Correct 1 ms 332 KB Output is correct
10 Correct 1 ms 332 KB Output is correct
11 Correct 1 ms 332 KB Output is correct

Subtask #2
3.0 / 3.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 332 KB Output is correct
2 Correct 2 ms 332 KB Output is correct

Subtask #3
4.0 / 4.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 348 KB Output is correct
2 Correct 4 ms 716 KB Output is correct

Subtask #4
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 13 ms 1100 KB Output is correct
2 Correct 30 ms 3768 KB Output is correct
3 Correct 18 ms 1236 KB Output is correct
4 Correct 8 ms 716 KB Output is correct

Subtask #5
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 38 ms 4908 KB Output is correct
2 Correct 56 ms 6208 KB Output is correct

Subtask #6
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 129 ms 10904 KB Output is correct
2 Correct 135 ms 17792 KB Output is correct
3 Correct 157 ms 29760 KB Output is correct

Subtask #7
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 221 ms 15924 KB Output is correct
2 Correct 306 ms 46612 KB Output is correct
3 Correct 352 ms 53300 KB Output is correct
4 Correct 410 ms 77100 KB Output is correct

Subtask #8
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 591 ms 31920 KB Output is correct
2 Correct 891 ms 100240 KB Output is correct
3 Correct 443 ms 30168 KB Output is correct
4 Correct 603 ms 77464 KB Output is correct
5 Correct 571 ms 76816 KB Output is correct
6 Correct 1806 ms 37364 KB Output is correct
7 Correct 602 ms 116904 KB Output is correct

Subtask #9
0 / 10.0

# Verdict Execution time Memory Grader output
1 Runtime error 413 ms 131072 KB Execution killed with signal 9
2 Halted 0 ms 0 KB -