#include<bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
typedef long long ll;
using namespace std;
using namespace __gnu_pbds;
#define ordered_set tree<x, null_type,
ll mod=(ll)1e9+7;
ll mod1=998244353;
///the defines :)
#define endl '\n'
#define vi vector<int>
#define ent(arr) for(int i=0;i<arr.size();i++)cin>>arr[i];
#define all(arr) arr.begin(),arr.end()
#define allr(arr) arr.rbegin(),arr.rend()
#define sz size()
#define int long long
int dp[100002][2][2][2];
bool vs[100002];
vector<vi>adj;
int u,v;
void cycle(int node,int parent)
{
vs[node]=true;
for(auto i:adj[node])
{
if(i==parent)continue;
if(vs[i])
{
u=node,v=i;
return;
}
cycle(i,node);
}
}
int lol=0;
map<int,int>mp;
int ans(int node,int color,int cansee,int vc,int parent)
{
if(node==v)color=vc;
if(node==v&&cansee&&lol)return 1e9;
if(node==v)cansee|=lol;
//cout<<node<<" "<<color<<" "<<cansee<<" "<<vc<<" "<<parent<<endl;
if(dp[node][color][cansee][vc]!=-1)return dp[node][color][cansee][vc];
if(cansee)
{
bool hi=false;
for(auto i:adj[node])
{
if(i==v&&i!=parent)hi=true;
}
if(vc&&hi)return 1e9;
else
{
int e=0;
for(auto i:adj[node])
{
if(i==parent||i==u)continue;
e+=ans(i,0,color,vc,node);
}
return dp[node][color][cansee][vc]=e;
}
}
else
{
int e=1e9,xd=0;
if(node==u)
{
e=1;
for(auto i:adj[node])
{
if(i==v||i==u)continue;
e+=ans(i,0,color,1,node);
xd+=ans(i,0,color,0,node);
}
for(auto i:adj[node])
{
if(i==v||i==u)continue;
e=min(e,xd-ans(i,0,color,0,node)+ans(i,1,color,0,node)+1);
}
}
else
{
bool hi=false;
for(auto i:adj[node])if(i==v&&parent!=i)hi=true;
if(hi&&vc){
e=0;
for(auto i:adj[node])if(i!=parent)e+=ans(i,0,color,vc,node);
}
else if(hi&&!vc)
{
e=0;
int cnt=0;
for(auto i:adj[node])
{
if(i==parent)continue;
e+=ans(i,0,color,vc,node);
cnt++;
}
if(cnt==1)return dp[node][color][cansee][vc]=1e9;
}
else
{
int cnt=0;
for(auto i:adj[node])
{
if(i==parent||i==u)continue;
xd+=ans(i,0,color,vc,node);
cnt++;
}
for(auto i:adj[node])
{
if(i==parent||i==u)continue;
if(i==v)continue;
e=min(e,xd-ans(i,0,color,0,node)+ans(i,1,color,0,node)+1);
}
if(cnt==0)e=1e9;
}
}
return dp[node][color][cansee][vc]=e;
}
}
void preprocess() {}
void solve()
{
memset(dp,-1,sizeof dp);
int n;
cin>>n;
adj.resize(n+1);
for(int i=0;i<n;i++)
{
int a,b;
cin>>a>>b;
adj[a].push_back(b);
adj[b].push_back(a);
}
cycle(1,0);
lol=1;
int x=ans(u,1,0,0,0)+1;
//cout<<x<<endl;
lol=0;
x=min(x,ans(u,0,0,0,0));
if(x>=1e9)cout<<-1<<endl;
else cout<<x<<endl;
}
signed main()
{
// freopen("meta_game_input.txt","r",stdin);
// freopen("otput.txt","w",stdout);
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
preprocess();
int t=1,st;
//cin>>t;
while(t--)
solve();
}
Compilation message
Main.cpp: In function 'int main()':
Main.cpp:155:13: warning: unused variable 'st' [-Wunused-variable]
155 | int t=1,st;
| ^~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1 ms |
6492 KB |
Output is correct |
| 2 |
Correct |
1 ms |
6492 KB |
Output is correct |
| 3 |
Incorrect |
1 ms |
6492 KB |
Output isn't correct |
| 4 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1 ms |
6648 KB |
Output is correct |
| 2 |
Incorrect |
1 ms |
6492 KB |
Output isn't correct |
| 3 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1 ms |
6648 KB |
Output is correct |
| 2 |
Incorrect |
1 ms |
6492 KB |
Output isn't correct |
| 3 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1 ms |
6492 KB |
Output is correct |
| 2 |
Correct |
1 ms |
6492 KB |
Output is correct |
| 3 |
Incorrect |
1 ms |
6492 KB |
Output isn't correct |
| 4 |
Halted |
0 ms |
0 KB |
- |
