Submission #959310

#	Time	Username	Problem	Language	Result	Execution time	Memory
959310		Cyber_Wolf	Pipes (CEOI15_pipes)	C++17	40 / 100	1050 ms	65536 KiB

pipes

#include <bits/stdc++.h>
 
using namespace std;
 
vector<int> adj[100005];
int tin[100005], par[100005][2], low[100005];
 
int get1(int src)
{
	return par[src][0] = (src == par[src][0] ? src : get1(par[src][0]));
}
 
int get2(int src)
{
	return par[src][1] = (src == par[src][1] ? src : get2(par[src][1]));
}
 
int n, m, tmp, pa = -1;
void dfs(int src)
{
	bool a = false;
	tin[src] = low[src] = ++tmp;
	for(auto it : adj[src])
	{
		if(it == pa && !a)
		{
			a = true;
			continue;
		}
		if(tin[it])
		{
			low[src] = min(low[src], tin[it]);
			continue;
		}
		swap(pa, src);
		dfs(it);
		swap(pa, src);
		low[src] = min(low[src], low[it]);
		if(low[it] > tin[src])
		{
			printf("%d %d\n", src, it);
		}
	}
	return ;
}
 
int main()
{
	scanf("%d%d", &n, &m);
	for(int i = 1; i <= n; i++)	par[i][0] = par[i][1] = i;
	int u, v, pU, pV;
	while(m--)
	{
		scanf("%d%d", &u, &v);
		pU = get1(u), pV = get1(v);
		if(pU != pV)
		{
			par[pU][0] = pV;
			adj[u].push_back(v), adj[v].push_back(u);
		}
		else{
			pU = get2(u), pV = get2(v);
			if(pU != pV)
			{
				par[pU][1] = pV;
				adj[u].push_back(v), adj[v].push_back(u);
			}
		}
	}
	for(int i = 1; i <= n; i++)
	{
		if(!tin[i])	dfs(i);
	}
 
    return 0;
}

Compilation message (stderr)

pipes.cpp: In function 'int main()':
pipes.cpp:49:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   49 |  scanf("%d%d", &n, &m);
      |  ~~~~~^~~~~~~~~~~~~~~~
pipes.cpp:54:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   54 |   scanf("%d%d", &u, &v);
      |   ~~~~~^~~~~~~~~~~~~~~~

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