Submission #1021719

#	Time	Username	Problem	Language	Result	Execution time	Memory
1021719		idiotcomputer	Pipes (CEOI15_pipes)	C++11	100 / 100	736 ms	14224 KiB

pipes

#pragma GCC optimize("O3,unroll-loops")
#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define sz size 
 
const int mxN = 1e5;
int n,m;

vector<int> adj[mxN];
int p[2*mxN];
 
void dfs(int c, int depth, int par){
	p[c] = depth;
	p[c+n] = p[c];
	int op = par;
	for (int i : adj[c]){
		if (i == par){par = -1; continue;}
		if (p[i] != -1){ p[c+n] = min(p[c+n],p[i]); continue;}
		dfs(i,depth+1,c);
		p[c+n] = min(p[c+n], p[i+n]);
	}
	if (p[c+n] >= depth && op != -1) cout << c+1 << " " << op+1 << '\n';
}
 

int gpar(const int &c){
	if (p[c] == c) return c;
	p[c] = gpar(p[c]);
	return p[c];
}

bool ss(const int &a, const int &b){
	return gpar(a) == gpar(b);
}

void un(const int &a, const int &b){
	p[gpar(a)] = gpar(b);
}

 
int main() {
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
 
	cin >> n >> m;
	for (int i = 0; i < 2* n; i++) p[i] = i;
 
	int a,b;
	for (int i = 0; i < m; i++){
		cin >> a >> b;
		a -= 1;
		b -= 1;
		if (!ss(a,b)) un(a,b);
		else if (!ss(a+n,b+n)) un(a+n,b+n);
		else continue;
		adj[a].pb(b);
		adj[b].pb(a);
	}
	for (int i = 0; i < n; i++) p[i] = -1;
	for (int i = 0; i < n; i++) if (p[i] == -1) dfs(i,0,-1);
	return 0;
}

• 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