Submission #147250

#	Time	Username	Problem	Language	Result	Execution time	Memory
147250		luciocf	Potemkin cycle (CEOI15_indcyc)	C++14	70 / 100	1087 ms	6904 KiB

indcyc

#include <bits/stdc++.h>

#pragma GCC optimize("Ofast")

using namespace std;
 
typedef pair<int, int> pii;

const int maxn = 1e3+10;
const int maxm = 1e5+10;
 
int mat[maxn][maxn];
 
int pai[maxn];
int dist[maxn];
 
bool nope[maxn];

pii edge[maxm];

vector<pii> grafo[maxn];
 
void bfs(int x, int nah)
{
	memset(dist, -1, sizeof dist);
 
	queue<int> fila;
 
	fila.push(x), dist[x] = 0, pai[x] = -1;
 
	while (!fila.empty())
	{
		int u = fila.front(); fila.pop();
 
		for (auto pp: grafo[u])
		{
			int v = pp.first;

			if (u == x && v == nah) continue;
			if (nope[v]) continue;
 
			if (dist[v] == -1)
			{
				dist[v] = dist[u]+1, pai[v] = u;
				fila.push(v);
			}
		}
	}
}
 
int main(void)
{
	int n, m;
	scanf("%d %d", &n, &m);
 
	for (int i = 1; i <= m; i++)
	{
		int u, v;
		scanf("%d %d", &u, &v);
 
		mat[u][v] = mat[v][u] = 1;
 
		grafo[u].push_back({v, i});
		grafo[v].push_back({u, i});

		edge[i] = {u, v};
	}
 	
 	for (int i = 1; i <= m; i++)
 	{
		memset(nope, 0, sizeof nope);

		int u = edge[i].first, v = edge[i].second;

		for (int w = 1; w <= n; w++)
			if (w != u && w != v && mat[w][u] && mat[w][v])
				nope[w] = 1;

		bfs(u, v);

		if (dist[v] != -1)
		{
			while (v != u)
			{
				printf("%d ", v);
				v = pai[v];
			}

			printf("%d\n", u);

			return 0;
		}
	}
 
	printf("no\n");
}

Compilation message (stderr)

indcyc.cpp: In function 'int main()':
indcyc.cpp:54:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d %d", &n, &m);
  ~~~~~^~~~~~~~~~~~~~~~~
indcyc.cpp:59:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d %d", &u, &v);
   ~~~~~^~~~~~~~~~~~~~~~~

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