Submission #1245312

#	Time	Username	Problem	Language	Result	Execution time	Memory
1245312		nanaseyuzuki	Pastiri (COI20_pastiri)	C++20	100 / 100	579 ms	95548 KiB

pastiri

#include <bits/stdc++.h>
/*
    --> Author: Kazuki_Hoshino__8703 <--
    I love Nanasaki Ai ☆*: .｡. o(≧▽≦)o .｡.:*☆
*/
#define fi first
#define se second
#define pii pair<int, int>
using namespace std;

const int mn = 5e5 + 5, bm = (1 << 15) + 1, mod = 1e9;
const int inf = 1e9 + 7;

int n, k, d[mn], par[mn];
vector <int> a[mn];

void dfs(int u, int p){
    for(auto v : a[u]){
        if(v == p) continue;
        d[v] = d[u] + 1;
        par[v] = u;
        dfs(v, u);
    }
}

vector <int> ilu;

int d1[mn], ok[mn];
vector <int> pre[mn], near[mn];

void bfs(){
    for(int i = 1; i <= n; i++) d1[i] = inf;
    queue <pii> q;
    for(auto i : ilu){
        d1[i] = 0;
        q.push({i, i});
    }
    while(q.size()){
        int u = q.front().fi;
        int p = q.front().se;
        q.pop();
        for(auto v : a[u]){
            if(d1[v] > d1[u] + 1){
                d1[v] = d1[u] + 1;
                q.push({v, p});
            }
        }
    }
}

void spread(int x){
    queue <int> q;
    q.push(x);
    while(q.size()){
        int u = q.front();
        q.pop();
        for(auto v : a[u]){
            if(ok[v] || d1[v] != d1[u] - 1) continue;
            ok[v] = 1;
            q.push(v);
        }
    }
}

bool cmp(int a, int b){
    return d[a] > d[b];
}

void solve(){
    cin >> n >> k;
    for(int i = 1; i < n; i++){
        int u, v; cin >> u >> v;
        a[u].push_back(v);
        a[v].push_back(u);
    }
    dfs(1, -1);
    for(int i = 1; i <= k; i++){
        int x; cin >> x;
        ilu.push_back(x);
    }
    bfs();
    sort(ilu.begin(), ilu.end(), cmp);
    vector <int> res;
    for(auto i : ilu){
        if(ok[i]) continue;
        int h = d[i];
        int target = i;
        while(par[target] != 0 && d1[par[target]] == d[i] - d[par[target]]){
            target = par[target];
        }
        res.push_back(target);
        spread(target);
    }
    cout << res.size() << '\n';
    for(auto i : res) cout << i << ' ';
}

main(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
    int t = 1;
    // cin >> t;
    while(t --){
        solve();
    }
}

Compilation message (stderr)

pastiri.cpp:98:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   98 | main(){
      | ^~~~

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