#include <bits/stdc++.h>
using namespace std;
typedef pair<int,int> pii;
vector<vector<int>> muchii;
int comp[100005],myroot[100005],dp[19][100005],val[100005],par[100005],niv[100005],lg[100005];
int n,m;
int what;
int LCA(int a,int b)
{
if(niv[a]<niv[b])
swap(a,b);
int dif=niv[a]-niv[b];
for(int i=0;i<=17;i++)
if((dif>>i)&1)
a=dp[i][a];
if(a==b)
return a;
for(int i=17;i>=0;i--)
if(dp[i][a]!=0&&dp[i][b]!=0)
if(dp[i][a]!=dp[i][b])
{
a=dp[i][a];
b=dp[i][b];
}
assert(par[a]==par[b]&&a!=b);
return par[a];
}
void dfscalc(int nod)
{
for(int q:muchii[nod])
{
int i=abs(q);
if(i!=par[nod])
{
dfscalc(i);
val[nod]+=val[i];
}
}
if(val[nod])
{
int a=min(nod,par[nod]);
int b=max(nod,par[nod]);
for(int &i:muchii[a])
if(i==b&&i>0)
i=-i;
for(int &i:muchii[b])
if(i==a&&i>0)
i=-i;
}
comp[nod]=what;
}
void dfsbuild(int nod)
{
val[nod]=0;
dp[0][nod]=par[nod];
for(int i=1;i<=17;i++)
dp[i][nod]=dp[i-1][dp[i-1][nod]];
for(int q:muchii[nod])
{
int i=abs(q);
if(i!=par[nod])
{
par[i]=nod;
niv[i]=niv[nod]+1;
dfsbuild(i);
}
}
}
void dsumerge(int a, int b)
{
int c1=comp[a],c2=comp[b];
if(lg[c1]<lg[c2])
{
swap(a,b);
swap(c1,c2);
}
what=c1;
dfscalc(myroot[c2]);
par[b]=a;
lg[c1]+=lg[c2];
lg[c2]=0;
niv[b]=niv[a]+1;
muchii[a].push_back(b);
muchii[b].push_back(a);
dfsbuild(b);
}
int main()
{
cin>>n>>m;
muchii.resize(n+1);
for(int i=1;i<=n;i++)
{
niv[i]=1;
lg[i]=1;
comp[i]=i;
myroot[i]=i;
par[i]=0;
val[i]=0;
}
int cnt=0;
for(int z=1;z<=m;z++)
{
int a,b;
cin>>a>>b;
if(comp[a]!=comp[b])
{
cnt++;
dsumerge(a,b);
}
else
{
int lca=LCA(a,b);
val[a]++;
val[b]++;
val[lca]-=2;
}
}
assert(cnt<=n-1);
for(int i=1;i<=n;i++)
if(lg[i])
dfscalc(myroot[i]);
for(int i=1;i<=n;i++)
for(int j:muchii[i])
if(j>i&&j>0)
cout<<i<<' '<<j<<'\n';
return 0;
}
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
340 KB |
Output is correct |
2 |
Correct |
0 ms |
340 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
8 ms |
980 KB |
Output is correct |
2 |
Correct |
8 ms |
1060 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
316 ms |
928 KB |
Output is correct |
2 |
Correct |
301 ms |
880 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
562 ms |
1844 KB |
Output is correct |
2 |
Correct |
644 ms |
1872 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
944 ms |
4028 KB |
Output is correct |
2 |
Correct |
778 ms |
4708 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1274 ms |
10768 KB |
Output is correct |
2 |
Correct |
1178 ms |
10772 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
2049 ms |
12472 KB |
Output is correct |
2 |
Runtime error |
2012 ms |
45836 KB |
Memory limit exceeded |
3 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
2917 ms |
15180 KB |
Output is correct |
2 |
Runtime error |
2913 ms |
56464 KB |
Memory limit exceeded |
3 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
3626 ms |
15120 KB |
Output is correct |
2 |
Runtime error |
3771 ms |
65536 KB |
Memory limit exceeded |
3 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
4469 ms |
14396 KB |
Output is correct |
2 |
Runtime error |
4139 ms |
65536 KB |
Memory limit exceeded |
3 |
Halted |
0 ms |
0 KB |
- |