#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
#define ALL(v) (v).begin(), (v).end()
#define MASK(i) (1LL << (i))
#define GETBIT(mask, i) (((mask) >> (i)) & 1)
// mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
mt19937_64 rng(1);
ll rngesus(ll l, ll r){return ((ull) rng()) % (r - l + 1) + l;}
ll max(ll a, ll b){return (a > b) ? a : b;}
ll min(ll a, ll b){return (a < b) ? a : b;}
ll LASTBIT(ll mask){return mask & (-mask);}
ll pop_cnt(ll mask){return __builtin_popcountll(mask);}
ll ctz(ll mask){return __builtin_ctzll(mask);}
ll clz(ll mask){return __builtin_clzll(mask);}
ll logOf(ll mask){return 63 - clz(mask);}
template <class T1, class T2>
bool minimize(T1 &a, T2 b){
if (a > b){a = b; return true;}
return false;
}
template <class T1, class T2>
bool maximize(T1 &a, T2 b){
if (a < b){a = b; return true;}
return false;
}
template <class T>
void printArr(T& a, string separator = " ", string finish = "\n", ostream& out = cout){
for(auto i: a) out << i << separator;
out << finish;
}
template <class T>
void remove_dup(vector<T> &a){
sort(ALL(a));
a.resize(unique(ALL(a)) - a.begin());
}
struct DSU{
int n;
vector<int> parent, sz;
DSU(int _n){
n = _n;
parent.resize(n+1); sz.resize(n+1, 1);
for(int i = 0; i<=n; ++i) parent[i] = i;
}
int find_set(int u){return (u == parent[u]) ? u : (parent[u] = find_set(parent[u]));}
bool same_set(int u,int v){return find_set(u) == find_set(v);}
bool join_set(int u, int v){
u = find_set(u), v = find_set(v);
if (u != v){
if (sz[u] < sz[v]) swap(u, v);
parent[v] = u;
sz[u] += sz[v];
return true;
}
return false;
}
};
const int N = 1e5 + 69;
vector<int> graph[N], chode[N];
int num[N], low[N];
int dfs_cnt = 0;
int edge_cnt = 0;
void tarjan(int u, int p){
num[u] = low[u] = ++dfs_cnt;
for(int v: graph[u]){
if (v == p){p = -1; continue;}
if (num[v]) minimize(low[u], num[v]);
else{
tarjan(v, u);
minimize(low[u], low[v]);
if (low[v] >= num[v]){
cout << u << " " << v << "\n";
}
}
}
}
int main(void){
ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
int n, m; cin >> n >> m;
DSU mst1(n), mst2(n);
for(int i = 1; i<=m; ++i){
int u, v; cin >> u >> v;
// if (i <= n-1) u = i, v = rngesus(i+1, n);
// else u = rngesus(1, n-1), v = rngesus(u+1, n);
if (mst1.join_set(u, v)){
edge_cnt++;
graph[u].push_back(v);
graph[v].push_back(u);
}
else{
mst2.join_set(u, v);
}
}
for(int i = 1; i<=n; ++i) if (mst2.sz[mst2.find_set(i)] > 1)
chode[mst2.find_set(i)].push_back(i);
for(int i = 1; i<=n; ++i) if (chode[i].size() >= 2){
edge_cnt += chode[i].size();
if (edge_cnt > 2e6) exit(1);
for(int j = 0; j < chode[i].size(); ++j){
int k = (j + 1) % chode[i].size();
int u = chode[i][j], v = chode[i][k];
graph[u].push_back(v);
graph[v].push_back(u);
}
}
for(int i = 1; i<=n; ++i) if (num[i] == 0) tarjan(i, i);
return 0;
}
Compilation message
pipes.cpp: In function 'int main()':
pipes.cpp:117:26: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
117 | for(int j = 0; j < chode[i].size(); ++j){
| ~~^~~~~~~~~~~~~~~~~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
2 ms |
5720 KB |
Output is correct |
| 2 |
Correct |
1 ms |
5728 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
4 ms |
6232 KB |
Output is correct |
| 2 |
Correct |
5 ms |
5984 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
76 ms |
9052 KB |
Output is correct |
| 2 |
Correct |
67 ms |
8820 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
144 ms |
11940 KB |
Output is correct |
| 2 |
Correct |
134 ms |
12368 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Runtime error |
193 ms |
16980 KB |
Memory limit exceeded |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Runtime error |
253 ms |
24224 KB |
Memory limit exceeded |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Runtime error |
404 ms |
32212 KB |
Memory limit exceeded |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Runtime error |
542 ms |
39468 KB |
Memory limit exceeded |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Runtime error |
688 ms |
45140 KB |
Memory limit exceeded |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Runtime error |
795 ms |
51612 KB |
Memory limit exceeded |
| 2 |
Halted |
0 ms |
0 KB |
- |
