This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include <bits/stdc++.h>
using namespace std;
struct Dsu
{
vector<int> p;
Dsu(size_t n) { p = vector<int>(n, -1); }
int repr(int u) { return p[u] < 0 ? u : p[u] = repr(p[u]); }
bool merge(int i, int j)
{
i = repr(i);
j = repr(j);
if (i == j)
return 0;
if (p[i] > p[j])
swap(i, j);
p[i] += p[j];
p[j] = i;
return 1;
}
};
constexpr size_t N = 100000;
vector<unsigned> g[N];
unsigned y[N];
pair<unsigned, unsigned> find_bridges(unsigned u, unsigned p, unsigned i)
{
unsigned lu = y[u] = ++i;
bool parent_seen = 0;
for (unsigned const &v : g[u])
{
if (!y[v])
{
unsigned lv;
tie(i, lv) = find_bridges(v, u, i);
lu = min(lu, lv);
if (lv > y[u])
printf("%u %u\n", u + 1, v + 1);
}
else if (v != p || parent_seen)
lu = min(lu, y[v]);
parent_seen = parent_seen || v == p;
}
return make_pair(i, lu);
}
int main()
{
size_t n, m;
scanf("%zu %zu", &n, &m);
Dsu d1(n), d2(n);
while (m--)
{
unsigned u, v;
scanf("%u %u", &u, &v);
u--, v--;
if (d1.merge(u, v) || d2.merge(u, v))
{
g[u].push_back(v);
g[v].push_back(u);
}
}
for (unsigned i = 0; i < n; i++)
if (!y[i])
find_bridges(i, UINT_MAX, 0);
}
Compilation message (stderr)
pipes.cpp: In function 'int main()':
pipes.cpp:58:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
58 | scanf("%zu %zu", &n, &m);
| ~~~~~^~~~~~~~~~~~~~~~~~~
pipes.cpp:65:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
65 | scanf("%u %u", &u, &v);
| ~~~~~^~~~~~~~~~~~~~~~~
# | Verdict | Execution time | Memory | Grader output |
---|
Fetching results... |
# | Verdict | Execution time | Memory | Grader output |
---|
Fetching results... |
# | Verdict | Execution time | Memory | Grader output |
---|
Fetching results... |
# | Verdict | Execution time | Memory | Grader output |
---|
Fetching results... |
# | Verdict | Execution time | Memory | Grader output |
---|
Fetching results... |
# | Verdict | Execution time | Memory | Grader output |
---|
Fetching results... |
# | Verdict | Execution time | Memory | Grader output |
---|
Fetching results... |
# | Verdict | Execution time | Memory | Grader output |
---|
Fetching results... |
# | Verdict | Execution time | Memory | Grader output |
---|
Fetching results... |
# | Verdict | Execution time | Memory | Grader output |
---|
Fetching results... |