#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)1e5];
bitset <N> g[N];
//vector <int> 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 = cnt[v][to];
if (how > 2) how = 2;
while (how --) {
// for (auto to : g[v]) {
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;
// }
cnt[x][y] ++;
cnt[y][x] ++;
g[x][y] = g[y][x] = 1;
// g[x].pb (y);
// g[y].pb (x);
}
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
pipes.cpp: In function 'void dfs(int, int)':
pipes.cpp:53:13: error: 'cnt' was not declared in this scope
int how = cnt[v][to];
^~~
pipes.cpp:53:13: note: suggested alternative: 'int'
int how = cnt[v][to];
^~~
int
pipes.cpp: In function 'void Solve()':
pipes.cpp:97:3: error: 'cnt' was not declared in this scope
cnt[x][y] ++;
^~~
pipes.cpp:97:3: note: suggested alternative: 'int'
cnt[x][y] ++;
^~~
int
pipes.cpp: At global scope:
pipes.cpp:110:7: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
main () {
^
