//#pragma GCC optimize("O3")
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/rope>
#define mem(a,v) memset((a), (v), sizeof (a))
#define enl printf("\n")
#define case(t) printf("Case #%d: ", (t))
#define ni(n) scanf("%d", &(n))
#define nl(n) scanf("%I64d", &(n))
#define nai(a, n) for (int i = 0; i < (n); i++) ni(a[i])
#define nal(a, n) for (int i = 0; i < (n); i++) nl(a[i])
#define pri(n) printf("%d\n", (n))
#define prl(n) printf("%I64d\n", (n))
#define pii pair<int, int>
#define pil pair<int, long long>
#define pll pair<long long, long long>
#define vii vector<pii>
#define vil vector<pil>
#define vll vector<pll>
#define vi vector<int>
#define vl vector<long long>
#define pb push_back
#define mp make_pair
#define fi first
#define se second
using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
typedef cc_hash_table<int,int,hash<int>> ht;
typedef tree<int,null_type,less<int>,rb_tree_tag,tree_order_statistics_node_update> oset;
const double pi = acos(-1);
const int MOD = 1e9 + 7;
const int INF = 1e9 + 7;
const int MAXN = 1e5 + 5;
const double eps = 1e-9;
vi adj[MAXN];
int cnt = 1, par[MAXN], par2[MAXN], lo[MAXN];
int qry(int x) { return x == par[x] ? x : par[x] = qry(par[x]); }
void join(int u, int v) { u = qry(u), v = qry(v); par[u] = v; }
int qry2(int x) { return x == par2[x] ? x : par2[x] = qry2(par2[x]); }
void join2(int u, int v) { u = qry2(u), v = qry2(v); par2[u] = v; }
void dfs(int u, int p) {
par[u] = lo[u] = cnt++;
while (!adj[u].empty()) {
int v = adj[u].back();
adj[u].pop_back();
if (!par[v]) {
dfs(v, u);
lo[u] = min(lo[u], lo[v]);
if (lo[v] > par[u] && qry2(u) != qry2(v))
printf("%d %d\n", u, v);
} else if (v != p)
lo[u] = min(lo[u], par[v]);
}
}
int main() {
int n, m;
scanf("%d %d", &n, &m);
for (int i = 1; i <= n; i++)
par[i] = par2[i] = i;
for (int i = 0; i < m; i++) {
int u, v; scanf("%d %d", &u, &v);
if (qry2(u) == qry2(v))
continue;
if (qry(u) == qry(v)) {
adj[u].pb(v);
adj[v].pb(u);
join2(u, v);
continue;
}
join(u, v);
adj[u].pb(v);
adj[v].pb(u);
}
for (int i = 1; i <= n; i++)
par[i] = lo[i] = 0;
for (int i = 1; i <= n; i++)
if (!par[i])
dfs(i, 0);
return 0;
}
Compilation message
pipes.cpp: In function 'int main()':
pipes.cpp:63:11: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
scanf("%d %d", &n, &m);
~~~~~^~~~~~~~~~~~~~~~~
pipes.cpp:67:22: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
int u, v; scanf("%d %d", &u, &v);
~~~~~^~~~~~~~~~~~~~~~~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
5 ms |
2680 KB |
Output is correct |
| 2 |
Correct |
6 ms |
2680 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
11 ms |
3064 KB |
Output is correct |
| 2 |
Correct |
9 ms |
2936 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
139 ms |
3020 KB |
Output is correct |
| 2 |
Correct |
137 ms |
2936 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
243 ms |
3580 KB |
Output is correct |
| 2 |
Correct |
282 ms |
3220 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
399 ms |
4856 KB |
Output is correct |
| 2 |
Correct |
346 ms |
4700 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
559 ms |
9336 KB |
Output is correct |
| 2 |
Correct |
495 ms |
6904 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
863 ms |
10340 KB |
Output is correct |
| 2 |
Correct |
818 ms |
8152 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1156 ms |
12148 KB |
Output is correct |
| 2 |
Correct |
1079 ms |
8416 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1397 ms |
12156 KB |
Output is correct |
| 2 |
Correct |
1319 ms |
8568 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1722 ms |
11600 KB |
Output is correct |
| 2 |
Correct |
1613 ms |
9548 KB |
Output is correct |
