#include<bits/stdc++.h>
#define taskname "sheep"
using namespace std;
const int inf=1e9;
struct Node{
int val, lazy;
Node (int a=inf, int b=0): val(a), lazy(b){}
friend Node operator+(const Node &a, const Node &b){
return Node(min(a.val, b.val));
}
};
struct SegmentTree{
int n;
vector<Node> t;
void init(int _n){
n=_n;
t.assign(4*n+1, Node());
}
void build(int k, int l, int r, int *a){
if (l==r){
t[k]=Node(a[l]);
return;
}
int mid=(l+r)>>1;
build(k<<1, l, mid, a);
build(k<<1|1, mid+1, r, a);
t[k]=t[k<<1]+t[k<<1|1];
}
void apply(int k, int val){
t[k].val+=val;
t[k].lazy+=val;
}
void push(int k){
apply(k<<1, t[k].lazy);
apply(k<<1|1, t[k].lazy);
t[k].lazy=0;
}
void point_update(int k, int l, int r, int pos, int val){
if (l==r){
t[k]=Node(val);
return;
}
push(k);
int mid=(l+r)>>1;
if (pos<=mid) point_update(k<<1, l, mid, pos, val);
else point_update(k<<1|1, mid+1, r, pos, val);
t[k]=t[k<<1]+t[k<<1|1];
}
void update(int k, int l, int r, int L, int R, int val){
if (r<L || R<l) return;
if (L<=l && r<=R){
apply(k, val);
return;
}
push(k);
int mid=(l+r)>>1;
update(k<<1, l, mid, L, R, val);
update(k<<1|1, mid+1, r, L, R, val);
t[k]=t[k<<1]+t[k<<1|1];
}
int walk(int k, int l, int r, int val){
if (l==r) return l;
push(k);
int mid=(l+r)>>1;
if (t[k<<1].val==val) return walk(k<<1, l, mid, val);
return walk(k<<1|1, mid+1, r, val);
}
} st;
const int N=5e5+1;
int n, k, a[N], dist[N], best[N], tin[N], tout[N], tdfs, f[N], vis[N], tour[N];
vector<int> g[N], trace[N], gg[N];
void pre_dfs(int u, int p){
tin[u]=++tdfs;
tour[tdfs]=u;
for (int v:g[u]) if (v!=p){
dist[v]=dist[u]+1;
pre_dfs(v, u);
}
tout[u]=tdfs;
}
void dfs(int u, int p){
best[u]=st.t[1].val;
for (int v:g[u]) if (v!=p){
st.update(1, 1, n, 1, n, 1);
st.update(1, 1, n, tin[v], tout[v], -2);
dfs(v, u);
st.update(1, 1, n, tin[v], tout[v], 2);
st.update(1, 1, n, 1, n, -1);
}
}
void dfs_trace(int u, int p){
best[u]=st.t[1].val;
if (f[u]){
vector<int> idx;
while (st.t[1].val==best[u]){
idx.push_back(st.walk(1, 1, n, best[u]));
st.point_update(1, 1, n, idx.back(), inf);
trace[u].push_back(tour[idx.back()]);
}
for (int i:idx) st.point_update(1, 1, n, i, best[u]);
}
for (int v:g[u]) if (v!=p){
st.update(1, 1, n, 1, n, 1);
st.update(1, 1, n, tin[v], tout[v], -2);
dfs_trace(v, u);
st.update(1, 1, n, tin[v], tout[v], 2);
st.update(1, 1, n, 1, n, -1);
}
}
int32_t main(){
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
// freopen(taskname".inp", "r", stdin);
// freopen(taskname".out", "w", stdout);
cin >> n >> k;
bool sub1=1;
for (int i=1; i<n; ++i){
int u, v; cin >> u >> v;
sub1&=abs(u-v)==1;
g[u].push_back(v);
g[v].push_back(u);
}
for (int i=1; i<=k; ++i){
int x; cin >> x;
a[x]=1;
}
if (sub1){
vector<int> v;
for (int i=1; i<=n; ++i) if (a[i]) v.push_back(i);
vector<int> ans;
for (int i=0; i<k; ++i){
if (i+1<k && (v[i+1]-v[i])%2==0){
ans.push_back((v[i+1]+v[i])/2);
++i;
}else ans.push_back(v[i]);
}
cout << ans.size() << '\n';
for (int i:ans) cout << i << ' ';
return 0;
}
pre_dfs(1, 0);
st.init(n);
for (int i=1; i<=n; ++i){
if (a[i]) st.point_update(1, 1, n, tin[i], dist[i]);
}
dfs(1, 0);
vector<int> ans;
for (int i=1; i<=n; ++i){
bool check=1;
for (int j:g[i]) check&=best[i]>=best[j];
if (check) f[i]=1, ans.push_back(i);
}
for (int i=1; i<=n; ++i){
if (a[i]) st.point_update(1, 1, n, tin[i], dist[i]);
}
dfs_trace(1, 0);
for (int i=1; i<=n; ++i){
sort(trace[i].begin(), trace[i].end(), [&](int x, int y){
return dist[x]<dist[y];
});
for (int j:trace[i]) gg[j].push_back(i);
}
set<pair<pair<int, int>, int>> st;
for (int i=1; i<=n; ++i) if (trace[i].size()) st.insert({{dist[trace[i].back()], -dist[i]}, i});
vector<int> real;
while (st.size()){
int idx=st.rbegin()->second; st.erase(prev(st.end()));
real.push_back(idx);
vis[idx]=1;
for (int j:trace[idx]) if (!vis[j]){
vis[j]=1;
for (int l:gg[j]) if (trace[l].size() && l!=idx){
st.erase({{dist[trace[l].back()], -dist[l]}, l});
while (trace[l].size() && vis[trace[l].back()]) trace[l].pop_back();
if (trace[l].size()) st.insert({{dist[trace[l].back()], -dist[l]}, l});
}
}
trace[idx].clear();
}
cout << real.size() << '\n';
for (int i:real) cout << i << ' ';
return 0;
}
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
103 ms |
55248 KB |
Output is correct |
| 2 |
Correct |
100 ms |
62800 KB |
Output is correct |
| 3 |
Correct |
111 ms |
62804 KB |
Output is correct |
| 4 |
Correct |
138 ms |
69984 KB |
Output is correct |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
15 ms |
46524 KB |
Output is correct |
| 2 |
Correct |
15 ms |
46168 KB |
Output is correct |
| 3 |
Execution timed out |
1073 ms |
119752 KB |
Time limit exceeded |
| 4 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Incorrect |
12 ms |
45912 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Execution timed out |
1098 ms |
99688 KB |
Time limit exceeded |
| 2 |
Halted |
0 ms |
0 KB |
- |
