Submission #604909

#	Time	Username	Problem	Language	Result	Execution time	Memory
604909		valerikk	Pipes (CEOI15_pipes)	C++17	40 / 100	1232 ms	46580 KiB

pipes

#include <bits/stdc++.h>
 
using namespace std;
 
#define x first
#define y second
#define all(a) begin(a), end(a)
#define sz(a) ((int) (a).size())
 
using ll = long long;
using ld = long double;
 
const int N = 1e5 + 7;
 
struct Dsu {
	int dsu[N];
 
	int get(int u) {
		return dsu[u] == u ? u : dsu[u] = get(dsu[u]);
	}
 
	void merge(int u, int v) {
		u = get(u);
		v = get(v);
		if (u != v) {
			dsu[u] = v;
		}
	}
 
	bool same(int u, int v) {
		return get(u) == get(v);
	}
 
	Dsu() {
		iota(all(dsu), 0);
	}
} dsu1, dsu2;
 
int n, m;
list<int> g[N];
int tin[N], fup[N], t = 0;
bool vis[N];
 
void dfs(int u, int p = -1) {
	vis[u] = true;
	tin[u] = t++;
	fup[u] = tin[u];
	for (const int &v : g[u]) {
		if (v == p) continue;
		if (!vis[v]) {
			dfs(v, u);
			fup[u] = min(fup[u], fup[v]);
			if (fup[v] > tin[u] && !dsu2.same(u, v)) {
				printf("%d %d\n", u, v);
			}
		} else {
			fup[u] = min(fup[u], tin[v]);
		}
	}
}
 
int main() {
	scanf("%d%d", &n, &m);
	for (int i = 0; i < m; ++i) {
		int a, b;
		scanf("%d%d", &a, &b);
		if (dsu1.same(a, b) && dsu2.same(a, b)) continue;
		g[a].push_back(b);
		g[b].push_back(a);
		if (dsu1.same(a, b)) {
			dsu2.merge(a, b);
		} else {
			dsu1.merge(a, b);
		}
	}
	for (int i = 1; i <= n; ++i) {
		if (!vis[i]) {
			dfs(i);
		}
	}
	return 0;
}

Compilation message (stderr)

pipes.cpp: In function 'int main()':
pipes.cpp:63:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   63 |  scanf("%d%d", &n, &m);
      |  ~~~~~^~~~~~~~~~~~~~~~
pipes.cpp:66:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   66 |   scanf("%d%d", &a, &b);
      |   ~~~~~^~~~~~~~~~~~~~~~

• 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