#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N = 1e5 + 10, MOD = 998244353;
#define int long long
int n;
vector<int> g[N];
vector<pair<int, int>> e;
int used[N], rt, sp, dp[N][2][2][2][2], sum[N][2][2][2][2];
void dfs(int v, int pr = -1)
{
used[v] = 1;
for (int to : g[v])
{
if (to == pr)
continue;
if (!used[to])
{
dfs(to, v);
}
else if (used[to] == 1)
{
sp = v;
rt = to;
}
}
used[v] = 2;
}
void fill(int v,int val){
for (int me = 0; me <= 1; me++)
{
for (int up = 0; up <= 1; up++)
{
for (int r = 0; r <= 1; r++)
{
for (int s = 0; s <= 1; s++)
{
dp[v][me][up][r][s] = val;
}
}
}
}
}
int go(int v,int me,int up,int r,int s,int pr = -1){
if(dp[v][me][up][r][s] != -1){
return dp[v][me][up][r][s];
}
int res = 1e9;
dp[v][me][up][r][s] = res;
if(v == sp &&me != s) return res;
if(v == rt && r != me) return res;
if(v == sp && up && rt) return res;
bool is_black = 0;
if(up) is_black = 1;
if(v == sp && r) is_black = 1;
if(v == rt && s) is_black = 1;
int sum = me;
for(int to:g[v]){
if(to == pr) continue;
sum += go(to,0,me,r,s,v);
}
if(is_black){
return dp[v][me][up][r][s] = sum;
}
for(int to:g[v]){
if(to == pr) continue;
res = min(dp[v][me][up][r][s],sum - go(to,0,me,r,s,v) + go(to,1,me,r,s,v));
}
return dp[v][me][up][r][s] = res;
}
void test()
{
cin >> n;
for (int i = 1; i <= n; i++)
{
int x, y;
cin >> x >> y;
g[x].push_back(y);
g[y].push_back(x);
e.push_back({x, y});
}
dfs(1);
for (int i = 1; i <= n; i++)
{
g[i].clear();
}
for (auto [x, y] : e)
{
if ((x == rt && y == sp) || (x == sp && y == rt))
continue;
g[x].push_back(y);
g[y].push_back(x);
}
int res = 1e9;
for(int i = 1;i <= n;i++){
fill(i,-1);
}
for (int me = 0; me <= 1; me++)
{
for (int up = 0; up <= 0; up++)
{
for (int r = 0; r <= 1; r++)
{
for (int s = 0; s <= 1; s++)
{
res = min(res,go(1,me,up,r,s));
// if(go(1,me,up,r,s) == 1){
// cout << me << ' ' << up << ' ' <<r << ' ' << s << '\n';
// }
}
}
}
}
if(res == 1e9) res = -1;
cout << res;
}
main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
int T = 1;
// cin >> T;
for (int i = 1; i <= T; i++)
{
test();
}
}
Compilation message
Main.cpp:117:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
117 | main()
| ^~~~
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
5724 KB |
Output is correct |
2 |
Correct |
1 ms |
5724 KB |
Output is correct |
3 |
Correct |
1 ms |
5724 KB |
Output is correct |
4 |
Correct |
1 ms |
5724 KB |
Output is correct |
5 |
Correct |
123 ms |
34408 KB |
Output is correct |
6 |
Correct |
129 ms |
34492 KB |
Output is correct |
7 |
Correct |
162 ms |
34492 KB |
Output is correct |
8 |
Correct |
136 ms |
34396 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
2 ms |
5724 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
2 ms |
5724 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
5724 KB |
Output is correct |
2 |
Correct |
1 ms |
5724 KB |
Output is correct |
3 |
Correct |
1 ms |
5724 KB |
Output is correct |
4 |
Correct |
1 ms |
5724 KB |
Output is correct |
5 |
Correct |
123 ms |
34408 KB |
Output is correct |
6 |
Correct |
129 ms |
34492 KB |
Output is correct |
7 |
Correct |
162 ms |
34492 KB |
Output is correct |
8 |
Correct |
136 ms |
34396 KB |
Output is correct |
9 |
Incorrect |
2 ms |
5724 KB |
Output isn't correct |
10 |
Halted |
0 ms |
0 KB |
- |