Submission #701079

#	Time	Username	Problem	Language	Result	Execution time	Memory
701079		aSSSd	Pastiri (COI20_pastiri)	C++14	100 / 100	847 ms	145740 KiB

pastiri

#include <bits/stdc++.h>
using namespace std;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
int rnd(int l,int r)
{
    return l+rng()%(r-l+1);
}
#define fasty ios_base::sync_with_stdio(0),cin.tie(0),cout.tie(0);
#define forinc(x,a,b) for(int x=a;x<=b;x++)
#define fordec(x,a,b) for(int x=a;x>=b;x--)
#define fi first
#define se second
#define ii pair<int,int>
#define getbit(x,i) ((x>>(i))&1ll)
#define batbit(x,i) (x|(1ll<<(i)))
#define tatbit(x,i) (x&~(1ll<<(i)))
#define endl '\n'
//#define int long long
#define pb push_back
const int N = 5e5+10;
int n, k;
int a[N], l[N];
vector<int> ke[N];
vector<int> adj[N];
int P[N][20];
void dfs(int u, int pr)
{
    forinc( i, 1,18 )   P[u][i] = P[P[u][i-1]][i-1];
    for(auto v : ke[u])
    {
        if(v==pr) continue;
        l[v] = l[u] + 1;
        P[v][0] = u;
        dfs(v,u);
    }
}
int d[N];
queue<int> q;
void bfs()
{
    while(!q.empty())
    {
        int u = q.front();
        q.pop();
        for(auto v : ke[u])
        {
            if(d[v] == -1)
            {
                d[v] = d[u] + 1;
                q.push(v);
            }
            if(d[v] == d[u] + 1)
            {
                adj[v].pb(u);
            }
        }
    }
}
bool cmp(int x, int y)
{
    return l[x] > l[y];
}
int dd[N];
main()
{
   // freopen("task.inp" , "r" , stdin);
    fasty;
    cin >> n >> k;
    forinc(i,1,n-1)
    {
        int a,b;
        cin >> a >> b;
        ke[a].pb(b);
        ke[b].pb(a);
    }
    dfs(1,0);
    forinc(i,1,n) d[i]=-1;
    forinc(i,1,k)
    {
        cin >> a[i];
        d[a[i]]=0;
        q.push(a[i]);
    }
    bfs();
    sort(a+1, a+k + 1, cmp);
    while(!q.empty()) q.pop();
    vector<int> ans;
    forinc(i,1,k)
    {
        if(dd[a[i]] ) continue;
        int cur=a[i];
        fordec(j,17,0)
        {
            int nxt = P[cur][j];
            if(!nxt) continue;
            if(l[a[i]] - l[nxt] <= d[nxt]) cur = nxt;
        }
        if(!dd[cur])
        {
            ans.pb(cur);
            dd[cur]=1;
            q.push(cur);
            while(!q.empty())
            {
                int u = q.front();
                q.pop();
                for(auto v : adj[u])
                {
                    if(!dd[v])
                    {
                        dd[v]=1;
                        q.push(v);
                    }
                }
            }
        }
    }
    cout << ans.size() << "\n";
    for(auto x : ans) cout << x << " ";
}

Compilation message (stderr)

pastiri.cpp:64:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   64 | main()
      | ^~~~

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