#include <bits/stdc++.h>
#define task "main"
using namespace std;
const long long inf = 1e9;
const int N = 1e5 + 5;
int n, RootTree, Spec, Par[N];
vector < int > V[N];
struct DisjointSet
{
int par[N];
void init()
{
for(int i = 1; i <= 1e5; i++) par[i] = -1;
}
int root(int u)
{
return (par[u] < 0) ? u : (par[u] = root(par[u]));
}
void Merge(int u, int v)
{
if((u = root(u)) == (v = root(v))) return;
if(par[u] > par[v]) swap(u, v);
par[u] += par[v];
par[v] = u;
}
} DSU;
void DFS(int u)
{
for(int v : V[u])
if(v != Par[u])
{
Par[v] = u;
DFS(v);
}
}
int dp[N][2][2][2][2];
int Sol(int x, int me, int up, int rt, int sp)
{
if(x == RootTree && me != rt) return inf;
if(x == Spec && me != sp) return inf;
if(x == Spec && up && rt) return inf;
if(dp[x][me][up][rt][sp] != -1) return dp[x][me][up][rt][sp];
bool covered = 0;
if(up) covered = 1;
if(x == RootTree && sp) covered = 1;
if(x == Spec && rt) covered = 1;
long long sum = me, Min = 1e9;
for(int v : V[x])
if(v != Par[x])
{
sum += 1LL * Sol(v, 0, me, rt, sp);
Min = min(Min, 1LL * (Sol(v, 1, me, rt, sp) - Sol(v, 0, me, rt, sp)));
}
if(covered) return dp[x][me][up][rt][sp] = sum;
return dp[x][me][up][rt][sp] = min(sum + Min, inf);
}
int main()
{
if(fopen(task ".inp","r"))
{
freopen(task ".inp","r",stdin);
freopen(task ".out","w",stdout);
}
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
cin >> n;
DSU.init();
for(int i = 1; i <= n; i++)
{
int u, v;
cin >> u >> v;
if(DSU.root(u) == DSU.root(v))
{
RootTree = u;
Spec = v;
}
else
{
DSU.Merge(u, v);
V[u].push_back(v);
V[v].push_back(u);
}
}
DFS(RootTree);
for(int i = 0; i <= n; i++)
for(int me = 0; me <= 1; me++)
for(int up = 0; up <= 1; up++)
for(int rt = 0; rt <= 1; rt++)
for(int sp = 0; sp <= 1; sp++) dp[i][me][up][rt][sp] = -1;
int ans = inf;
for(int rt = 0; rt <= 1; rt++)
for(int sp = 0; sp <= 1; sp++)
ans = min(ans, Sol(RootTree, rt, 0, rt, sp));
if(ans == inf) cout << -1;
else cout << ans;
}
Compilation message
Main.cpp: In function 'int main()':
Main.cpp:63:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
63 | freopen(task ".inp","r",stdin);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:64:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
64 | freopen(task ".out","w",stdout);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
3012 KB |
Output is correct |
2 |
Correct |
2 ms |
3020 KB |
Output is correct |
3 |
Correct |
2 ms |
3020 KB |
Output is correct |
4 |
Correct |
2 ms |
3020 KB |
Output is correct |
5 |
Correct |
173 ms |
26488 KB |
Output is correct |
6 |
Correct |
188 ms |
26396 KB |
Output is correct |
7 |
Correct |
185 ms |
26492 KB |
Output is correct |
8 |
Correct |
202 ms |
26436 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Incorrect |
2 ms |
3020 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Incorrect |
2 ms |
3020 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
3012 KB |
Output is correct |
2 |
Correct |
2 ms |
3020 KB |
Output is correct |
3 |
Correct |
2 ms |
3020 KB |
Output is correct |
4 |
Correct |
2 ms |
3020 KB |
Output is correct |
5 |
Correct |
173 ms |
26488 KB |
Output is correct |
6 |
Correct |
188 ms |
26396 KB |
Output is correct |
7 |
Correct |
185 ms |
26492 KB |
Output is correct |
8 |
Correct |
202 ms |
26436 KB |
Output is correct |
9 |
Incorrect |
2 ms |
3020 KB |
Output isn't correct |
10 |
Halted |
0 ms |
0 KB |
- |