Submission #604940

#	Time	Username	Problem	Language	Result	Execution time	Memory
604940		valerikk	Pipes (CEOI15_pipes)	C++17	100 / 100	1255 ms	13064 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;

int mem[2 * N];

int *dsu1 = &mem[0];
int *dsu2 = &mem[N];

int get1(int u) {
	return dsu1[u] == u ? u : dsu1[u] = get1(dsu1[u]);
}

int get2(int u) {
	return dsu2[u] == u ? u : dsu2[u] = get2(dsu2[u]);
}

void merge1(int u, int v) {
	u = get1(u);
	v = get1(v);
	if (u != v) {
		dsu1[u] = v;
	}
}

void merge2(int u, int v) {
	u = get2(u);
	v = get2(v);
	if (u != v) {
		dsu2[u] = v;
	}
}

bool same1(int u, int v) {
	return get1(u) == get1(v);
}

bool same2(int u, int v) {
	return get2(u) == get2(v);
}

int n, m;
int ex[2 * N], es = 0;
vector<int> g[N];
int *tin = &mem[0];
int *fup = &mem[N];
int t = 0;
bool vis[N];

void dfs(int u, int pe = -1) {
	vis[u] = true;
	tin[u] = t++;
	fup[u] = tin[u];
	for (const int &e : g[u]) {
		if (e == pe) continue;
		int v = ex[e] ^ u;
		if (!vis[v]) {
			dfs(v, e);
			fup[u] = min(fup[u], fup[v]);
			if (fup[v] > tin[u]) {
				printf("%d %d\n", u + 1, v + 1);
			}
		} else {
			fup[u] = min(fup[u], tin[v]);
		}
	}
}
 
int main() {
	scanf("%d%d", &n, &m);
	for (int i = 0; i < n; ++i) {
		dsu1[i] = dsu2[i] = i;
	}
	for (int i = 0; i < m; ++i) {
		int a, b;
		scanf("%d%d", &a, &b);
		--a, --b;
		if (same1(a, b) && same2(a, b)) continue;
		int e = es++;
		g[a].push_back(e);
		g[b].push_back(e);
		ex[e] = a ^ b;
		++e;
		if (same1(a, b)) {
			merge2(a, b);
		} else {
			merge1(a, b);
		}
	}
	for (int i = 0; i < n; ++i) {
		if (!vis[i]) {
			dfs(i);
		}
	}
	return 0;
}

Compilation message (stderr)

pipes.cpp: In function 'int main()':
pipes.cpp:80:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   80 |  scanf("%d%d", &n, &m);
      |  ~~~~~^~~~~~~~~~~~~~~~
pipes.cpp:86:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   86 |   scanf("%d%d", &a, &b);
      |   ~~~~~^~~~~~~~~~~~~~~~

• 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: 10 / 10
• Subtask 9: 10 / 10
• Subtask 10: 10 / 10