#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];
int loga=log2(dif);
for(int i=0;i<=loga;i++)
if((dif>>i)&1)
a=dp[i][a];
if(a==b)
return a;
loga=log2(niv[a]);
for(int i=loga;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];
}
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[b])
if(i==a&&i>0)
{
i=-i;
break;
}
}
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;
}
}
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 |
1 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 |
1044 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
347 ms |
852 KB |
Output is correct |
2 |
Correct |
311 ms |
972 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
581 ms |
1828 KB |
Output is correct |
2 |
Correct |
682 ms |
1816 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1034 ms |
3912 KB |
Output is correct |
2 |
Correct |
867 ms |
4928 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1412 ms |
10768 KB |
Output is correct |
2 |
Correct |
1237 ms |
10884 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
2280 ms |
12340 KB |
Output is correct |
2 |
Correct |
2178 ms |
12272 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
3072 ms |
15092 KB |
Output is correct |
2 |
Correct |
2784 ms |
15124 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
3903 ms |
15088 KB |
Output is correct |
2 |
Correct |
3531 ms |
15288 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
4491 ms |
14344 KB |
Output is correct |
2 |
Correct |
4322 ms |
15356 KB |
Output is correct |