Submission #86699

#	Time	Username	Problem	Language	Result	Execution time	Memory
86699		Pancake	Pipes (CEOI15_pipes)	C++14	0 / 100	384 ms	65536 KiB

pipes

#pragma GCC optimize("Ofast")
#pragma GCC target("sse,sse2,sse3,sse3,sse4,popcnt,abm,mmx")

#include <bits/stdc++.h>	
#include <stdio.h>    
 
using namespace std;
     
#define F first
#define S second
#define lb lower_bound          	    
#define ub upper_bound
#define pb push_back
#define pf push_front    
#define ppb pop_back
#define mp make_pair
#define bpp __builtin_popcount                                                                                        
#define sqr(x) ((x) * (x))
#define al 0x3F3F3F3F
#define sz(x) (int)x.size()
#define all(x) x.begin(), x.end()
#define in insert
#define ppf pop_front
#define endl '\n'
//#define int long long
 
typedef unsigned long long ull;
typedef long long ll;
typedef long double ld;
typedef pair <int, int> pii;
 
const int mod = (int)1e9 + 7;                                  
const int N = (int)3e4 + 123;
const ll inf = (ll)3e18 + 1;
                                       
const double pi = acos(-1.0);
const double eps = 1e-7;
const int dx[] = {0, 0, 1, 0, -1};   																																					
const int dy[] = {0, 1, 0, -1, 0};  

int n, m, tin[N], fup[N], timer;
bool used[N];
set <pii> ans;
int u[N * 10 + (int)3e4];
bitset <N> g[N];

void dfs (int v, int p = 0) {
	used[v] = 1;
	tin[v] = fup[v] = ++ timer;
	int ok = 0;
	for (int to = g[v]._Find_first (); to < sz (g[v]); to = g[v]._Find_next (to)) {
		int how = min (u[v * 10 + to], 3);
		while (how --) {
		if (to == p) {
	//		if (u[to * 10 + v] == -1) {
	//			fup[v] = min (fup[v], tin[to]);
	//		}
			if (!ok) {
				ok ++;
				continue;
			}
		}                    
	//	cout << v << ' ' << to << endl;
		if (used[to]) fup[v] = min (fup[v], tin[to]);
		else {
			dfs (to, v);
			fup[v] = min (fup[v], fup[to]);
			if (fup[to] > tin[v]) {
	//			if (u[to * 10 + v] == -1) continue;
				ans.in ({min (v, to), max (v, to)});
			}
		}
		}
	}     
}

inline void boost () {
	ios_base :: sync_with_stdio (NULL);
	cin.tie (NULL), cout.tie (NULL);          
}

inline void Solve () {
	cin >> n >> m;
	while (m --) {
		int x, y;
		cin >> x >> y;
		if (x == y) continue;
//		if (u[x * 10 + y] == -1 || u[y * 10 + x] == -1) continue;
		u[x * 10 + y] ++, u[y * 10 + x] ++;
	//	if (u[x * 10 + y] > 1) {
//			u[x * 10 + y] = u[y * 10 + x] = -1;
	//		continue;
//		}
		g[x][y] = g[y][x] = 1;
	}
	for (int i = 1; i <= n; i ++) 
		if (!used[i])
			dfs (i);
	for (auto to : ans)
		cout << to.F << ' ' << to.S << endl;
}                                          
                  
main () {                                       
//	freopen ("gcm.in", "r", stdin);    
//	freopen ("gcm.out", "w", stdout); 	          
	boost ();
	int tt = 1;
//	cin >> tt;   
	while (tt --) {                  
		Solve ();
	}                                               
	return 0;      
}                                                             

Compilation message (stderr)

pipes.cpp:103:7: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
 main () {                                       
       ^

• Subtask 1: 0 / 10
• Subtask 2: 0 / 10
• Subtask 3: 0 / 10
• Subtask 4: 0 / 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