oj.uz

Submission #125097

# Submission time Handle Problem Language Result Execution time Memory
125097 2019-07-04T15:17:51 Z NMAC427 Islands (IOI08_islands) C++17
0 / 100
 774 ms 131076 KB 
// https://oj.uz/problem/view/IOI08_islands

#include <bits/stdc++.h>
#define coutV(v) for (auto &e: v) {cerr << e << " ";} cerr << "\n"
#define int int64_t
#define ff first
#define ss second

using namespace std;

int N;

vector<pair<int, int>> to;
vector<vector<int>> from;
vector<bool> inCycle;

pair<int, int> dfsSolve(int v) {
	int max1 = 0;
	int max2 = 0;

	int maxInternal = 0; // Maximum internal path;

	for (const int child: from[v]) {
		if (inCycle[child]) continue;  // Check here because we want to be able to pass in a node of the cycle

		auto childDFS = dfsSolve(child);
		childDFS.ff += to[child].ss;

		if (childDFS.ss >= max1) {
			max2 = max1;
			max1 = childDFS.ff;
		} else if (childDFS.ss > max2) {
			max2 = childDFS.ff;
		}

		maxInternal = max(maxInternal, childDFS.ff);
	}

	maxInternal = max(maxInternal, max1 + max2);

	return {max1, maxInternal};
}

signed main() {

	#ifndef __APPLE__
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	#endif

	cin >> N;

	to.resize(N);
	from.resize(N);

	for (int i = 0; i < N; i++) {
		cin >> to[i].ff >> to[i].ss;
		to[i].ff -= 1;

		from[to[i].ff].push_back(i);
	}


	// Generate inCycle Vector
	inCycle.assign(N, false);

	vector<bool> visited (N, false);
	vector<int> __cycle;

	for (int i = 0; i < N; i++) {
		if (visited[i]) continue;

		__cycle.clear();

		queue<int> q;
		q.push(i);

		while (!q.empty()) {
			auto front = q.front();
			q.pop();

			__cycle.push_back(front);

			if (visited[front]) {
				bool __inCycle = false;
				for (auto v: __cycle)  {
					if (to[i].ff == v) __inCycle = true;
					if (__inCycle) inCycle[v] = true;
				}

				continue;
			}

			visited[front] = true;
			q.push(to[front].ff);
		}
	}

	// Solve
	int ans = 0;

	for (int i = 0; i < N; i++) {
		if (!inCycle[i]) continue;

		int compAns = 0;

		int next = i;
		vector<int> cycle;
		vector<int> dfsV;

		do {
			auto dfs = dfsSolve(next);
			compAns = max(compAns, dfs.ss);  // Internal Path

			cycle.push_back(next);
			dfsV.push_back(dfs.ff);
			next = to[next].ff;
		} while (next != i);

		for (int v: cycle) {
			inCycle[v] = false;  // Don't visit same component twice
		}

		coutV(cycle);

		int leftPtr = 0;
		int rightPtr = 1;
		int diameter = cycle.size();
		int prefix = dfsV[0] + to[i].ss;

		while (leftPtr < diameter && rightPtr < diameter * 2) {

			// cerr << leftPtr << " " << rightPtr << "\n";

			if (leftPtr == (rightPtr % diameter)) {
				prefix -= dfsV[leftPtr];
				prefix -= to[cycle[leftPtr]].ss;
				leftPtr++;
			}

			compAns = max(compAns, prefix + dfsV[rightPtr % diameter]);

			if (prefix <= dfsV[rightPtr % diameter]) {
				prefix  = dfsV[rightPtr % diameter];
				leftPtr = rightPtr % diameter;
			}
			
			prefix   += to[cycle[rightPtr % diameter]].ss;
			rightPtr += 1;
		}

		cerr << "CompAns = " << compAns << "\n";
		cerr << "-----------------\n";

		ans += compAns;
	}

	cout << ans << "\n";

	return 0;
}

Subtask #1
0 / 33.0

# Verdict Execution time Memory Grader output
1 Incorrect 2 ms 376 KB Output isn't correct
2 Runtime error 353 ms 131076 KB Execution killed with signal 9 (could be triggered by violating memory limits)
3 Incorrect 4 ms 376 KB Output isn't correct
4 Runtime error 117 ms 131076 KB Execution killed with signal 9 (could be triggered by violating memory limits)
5 Incorrect 2 ms 376 KB Output isn't correct
6 Incorrect 2 ms 376 KB Output isn't correct
7 Incorrect 2 ms 380 KB Output isn't correct
8 Runtime error 350 ms 131076 KB Execution killed with signal 9 (could be triggered by violating memory limits)
9 Incorrect 3 ms 376 KB Output isn't correct
10 Incorrect 2 ms 380 KB Output isn't correct
11 Incorrect 4 ms 376 KB Output isn't correct

Subtask #2
0 / 3.0

# Verdict Execution time Memory Grader output
1 Runtime error 142 ms 131076 KB Execution killed with signal 9 (could be triggered by violating memory limits)
2 Halted 0 ms 0 KB -

Subtask #3
0 / 4.0

# Verdict Execution time Memory Grader output
1 Runtime error 348 ms 131076 KB Execution killed with signal 9 (could be triggered by violating memory limits)
2 Halted 0 ms 0 KB -

Subtask #4
0 / 10.0

# Verdict Execution time Memory Grader output
1 Runtime error 677 ms 131076 KB Execution killed with signal 9 (could be triggered by violating memory limits)
2 Halted 0 ms 0 KB -

Subtask #5
0 / 10.0

# Verdict Execution time Memory Grader output
1 Runtime error 326 ms 131072 KB Execution killed with signal 9 (could be triggered by violating memory limits)
2 Halted 0 ms 0 KB -

Subtask #6
0 / 10.0

# Verdict Execution time Memory Grader output
1 Runtime error 774 ms 131076 KB Execution killed with signal 9 (could be triggered by violating memory limits)
2 Halted 0 ms 0 KB -

Subtask #7
0 / 10.0

# Verdict Execution time Memory Grader output
1 Runtime error 471 ms 131076 KB Execution killed with signal 9 (could be triggered by violating memory limits)
2 Halted 0 ms 0 KB -

Subtask #8
0 / 10.0

# Verdict Execution time Memory Grader output
1 Incorrect 411 ms 53732 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #9
0 / 10.0

# Verdict Execution time Memory Grader output
1 Runtime error 464 ms 131076 KB Execution killed with signal 9 (could be triggered by violating memory limits)
2 Halted 0 ms 0 KB -