Submission #759016

#	Time	Username	Problem	Language	Result	Execution time	Memory
759016		Ronin13	Pastiri (COI20_pastiri)	C++14	0 / 100	442 ms	79820 KiB

pastiri

#include <bits/stdc++.h>
#define ll long long
#define ull unsigned ll
#define f first
#define s second
#define pii pair<int,int>
#define pll pair<ll,ll>
#define pb push_back
#define epb emplace_back
using namespace std;
const int nmax = 500001;

int x[nmax], d[nmax];
bool active[nmax];
int dp[nmax];
vector <vector <int> > g(nmax);

void dfs(int v, int e = -1){
    for(int to : g[v]){
        if(to == e) continue;
        dfs(to, v);
        d[v] = min(d[v], d[to] + 1);
    }
}

vector <int> ans;

void DFS(int v, int e = -1){
    for(int to : g[v]){
        if(to == e) continue;
        DFS(to, v);
        active[v] |= active[to];
        dp[v] = max(dp[v], dp[to] - 1);
    }
    if(v == 1 && active[v]){
        if(dp[v] >= d[v]) return;
        ans.pb(v);
        dp[v] = 0;
        return;
    }
    if(!active[v])
        return;
    if(d[e] == x[e] && d[e] == d[v] + 1){
        return;
    }
    if(dp[v] >= d[v])
        return;
    dp[v] = d[v];
    active[v] = false;
    ans.pb(v);
}

int main(){
    ios_base::sync_with_stdio(false); cin.tie(0);
    int n; cin >> n;
    int k; cin >> k;
    for(int i = 1; i < n; i++){
        int u, v; cin >> u >> v;
        g[u].pb(v);
        g[v].pb(u);
    }
    //int k; cin >> k;
    for(int i = 1; i <= n; i++){
        x[i] = d[i] = 1e9;
        dp[i] = -1e9;
    }
    queue <int> q;
    for(int i = 1; i <= k; ++i){
        int y; cin >> y;
        q.push(y);
        active[y] = true;
        x[y] = d[y] = 0;
    }
    while(!q.empty()){
        int v = q.front();
        q.pop();
        for(int to : g[v]){
            if(x[to] <= x[v]) continue;
            x[to] = x[v] + 1;
            q.push(to);
        }
    }
    dfs(1);
    DFS(1);
    cout << ans.size() << "\n";
    sort(ans.begin(), ans.end());
    for(int to : ans)
        cout << to << ' ';
    return 0;
}

• Subtask 1: 0 / 8
• Subtask 2: 0 / 18
• Subtask 3: 0 / 23
• Subtask 4: 0 / 51