oj.uz

Submission #546458

# Submission time Handle Problem Language Result Execution time Memory
546458 2022-04-07T15:41:43 Z blue Pipes (CEOI15_pipes) C++17
40 / 100
 1127 ms 65536 KB 
#include <iostream>
#include <vector>
using namespace std;

const int mx = 100'000;


int N, M;

struct disjoint_set
{
	int* parent = new int[1+mx];
	int* subtree = new int[1+mx];

	disjoint_set()
	{
		for(int i = 1; i <= mx; i++)
		{
			parent[i] = i;
			subtree[i] = 1;
		}
	}

	int root(int u)
	{
		if(parent[u] == u) return u;
		else return (parent[u] = root(parent[u]));
	}

	bool join(int u, int v)
	{
		u = root(u);
		v = root(v);
		if(u == v) return 0;

		if(subtree[u] < subtree[v]) swap(u, v);
		parent[v] = u;
		subtree[u] += subtree[v];

		return 1;
	}
};

int lowlink[1+mx];

int dfsind[1+mx];

int dfscurr;

int paredge[1+mx];

int degree[1+mx];

int* edgelist[1+mx];

int eu[2*mx + 1], ev[2*mx + 1];


void dfs(int u)
{
	// cerr << "dfs " << u << '\n';
	// cerr << "paredge = ";
	// for(int i = 1; i <= N; i++) cerr << paredge[i] << ' ';
		// cerr << '\n';
	dfsind[u] = ++dfscurr;

	for(int h = 0; h < degree[u]; h++)
	{
		int e = edgelist[u][h];
		if(e == paredge[u]) continue;

		int v = eu[e] + ev[e] - u;

		if(dfsind[v] == 0)
		{
			// cerr << "edge " << u << " -> " << v << '\n';
			paredge[v] = e;
			dfs(v);
			lowlink[u] = min(lowlink[u], lowlink[v]);
		}
		else
		{
			lowlink[u] = min(lowlink[u], dfsind[v]);
		}
	}

	// cerr << "dfs end " << u << " : " << lowlink[u] << ' ' << dfsind[u] << '\n';
	// cerr << "paredge = ";
	// for(int i = 1; i <= N; i++) cerr << paredge[i] << ' ';
	// 	cerr << '\n';

	if(lowlink[u] >= dfsind[u] && paredge[u] != 0)
	{
		// cerr << "\n\n";
		// cerr << "paredge " << u << " = " << paredge[u] << '\n';
		// cerr << "bridge detected : ";
		cout << eu[paredge[u]] << ' ' << ev[paredge[u]] << '\n';
		// cerr << "\n\n";
	}
}


int main()
{
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);

	cin >> N >> M;

	disjoint_set A;
	disjoint_set B;

	int ect = 0;



	for(int e = 1; e <= M; e++)
	{
		int u, v;
		cin >> u >> v;

		if(A.join(u, v))
		{
			ect++;
			eu[ect] = u;
			ev[ect] = v;
		}
		else if(B.join(u, v))
		{
			ect++;
			eu[ect] = u;
			ev[ect] = v;
		}
	}

	delete[] A.parent;
	delete[] A.subtree;
	delete[] B.parent;
	delete[] B.subtree;

	for(int i = 1; i <= N; i++) degree[i] = 0;

	for(int e = 1; e <= ect; e++)
	{
		degree[eu[e]]++;
		degree[ev[e]]++;
	}

	for(int i = 1; i <= N; i++)
	{
		edgelist[i] = new int[degree[i]];
	}


	int currind[1+N];
	for(int i = 1; i <= N; i++) currind[i] = -1;

	// cerr << "done\n";

	for(int e = 1; e <= ect; e++)
	{
		currind[eu[e]]++;
		currind[ev[e]]++;

		// cerr << currind[eu[e]] << ' ' << degree[eu[e]] << '\n';
		// cerr << currind[ev[e]] << ' ' << degree[ev[e]] << '\n';

		edgelist[eu[e]][currind[eu[e]]] = e;
		edgelist[ev[e]][currind[ev[e]]] = e;
	}

// cerr << "\n\n\n\n";

	for(int i = 1; i <= N; i++) 
	{
		lowlink[i] = 1'000'000;
		dfsind[i] = 0;
		paredge[i] = 0;
	}

	dfscurr = 0;

	for(int i = 1; i <= N; i++)
	{
		if(dfsind[i]) continue;

		dfs(i);
	}
}

Subtask #1
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 1876 KB Output is correct
2 Correct 1 ms 1876 KB Output is correct

Subtask #2
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 1876 KB Output is correct
2 Correct 4 ms 2012 KB Output is correct

Subtask #3
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 115 ms 1960 KB Output is correct
2 Correct 89 ms 2152 KB Output is correct

Subtask #4
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 164 ms 2076 KB Output is correct
2 Correct 180 ms 2260 KB Output is correct

Subtask #5
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 246 ms 3388 KB Output is correct
2 Runtime error 242 ms 17260 KB Memory limit exceeded
3 Halted 0 ms 0 KB -

Subtask #6
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 314 ms 9616 KB Output is correct
2 Runtime error 315 ms 24472 KB Memory limit exceeded
3 Halted 0 ms 0 KB -

Subtask #7
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 554 ms 11036 KB Output is correct
2 Runtime error 535 ms 41628 KB Memory limit exceeded
3 Halted 0 ms 0 KB -

Subtask #8
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 670 ms 13508 KB Output is correct
2 Runtime error 678 ms 50048 KB Memory limit exceeded
3 Halted 0 ms 0 KB -

Subtask #9
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 843 ms 13656 KB Output is correct
2 Runtime error 864 ms 61500 KB Memory limit exceeded
3 Halted 0 ms 0 KB -

Subtask #10
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 1090 ms 13212 KB Output is correct
2 Runtime error 1127 ms 65536 KB Memory limit exceeded
3 Halted 0 ms 0 KB -