Submission #1023320

#	Time	Username	Problem	Language	Result	Execution time	Memory
1023320		MarwenElarbi	Pastiri (COI20_pastiri)	C++17	100 / 100	493 ms	115352 KiB

pastiri

#include <bits/stdc++.h>
using namespace std;
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#pragma GCC optimize("Ofast,no-stack-protector")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,avx2,tune=native")
#define ll long long
#define fi first
#define se second
#define pb push_back
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
const int nax=5e5+5;
vector<int> adj[nax];
bool sheep[nax];
bool removed[nax];
bool ans[nax];
int sz[nax];
int dep[nax];
int dp[20][nax];
vector<pair<int,int>> parent[nax];
int dis[nax];
queue<pair<int,int>> q;
void bfs(){
    while(!q.empty()){
        auto cur=q.front();
        q.pop();
        for(auto u:adj[cur.se]){
            if(dis[u]>cur.fi+1){
                dis[u]=cur.fi+1;
                q.push({cur.fi+1,u});
            }
        }
    }
}
void dfs(int x,int p){
    for (int i = 1; i < 20; ++i)
    {
        dp[i][x]=dp[i-1][dp[i-1][x]];
    }
    for(auto u:adj[x]){
        if(u==p) continue;
        dep[u]=dep[x]+1;
        dp[0][u]=x;
        dfs(u,x);
    }
    return;
}
int jump(int x,int d){
    for (int i = 19; i >= 0; --i)
    {
        if(d&(1<<i)) x=dp[i][x];
    }
    return x;
}
bool compare(int x,int y){
    return dep[x]<dep[y];
}
bool vis[nax];
void dfs2(int x){
    vis[x]=true;
    for(auto u:adj[x]){
        if(vis[u]) continue;
        if(dis[x]==dis[u]+1) dfs2(u);
    }
}
signed main(){
    iostream::sync_with_stdio(false);
    int n,k;
    cin>>n>>k;
    vector<int> tab(k);
    for (int i = 0; i < n; ++i)
    {
        dis[i]=1e9;
    }
    for (int i = 0; i < n-1; ++i)
    {
        int x,y;
        cin>>x>>y;
        x--;y--;
        adj[x].pb(y);
        adj[y].pb(x);
    }
    for (int i = 0; i < k; ++i)
    {
        int x;
        cin>>x;
        tab[i]=x-1;
        sheep[--x]=true;
        dis[x]=0;
        q.push({0,x});
    }
    bfs();
    for (int i = 0; i < n; ++i)
    {
        for(auto u:parent[i]){
            dis[i]=min(dis[i],u.se+dis[u.fi]);
        }
    }
    dfs(0,-1);
    sort(tab.rbegin(),tab.rend(),compare);
    for (int i = 0; i < k; ++i)
    {
        if(vis[tab[i]]) continue;
        int cur=0;
        for (int j = 19; j >= 0; --j)
        {
            cur+=(1<<j);
            if(dis[dp[j][tab[i]]]==cur) tab[i]=dp[j][tab[i]];
            else cur-=(1<<j);
        }
        ans[tab[i]]=1;
        dfs2(tab[i]);
    }
    vector<int> cnt;
    for (int i = 0; i < n; ++i)
    {
        if(ans[i]==1) cnt.pb(i);
    }
    cout <<cnt.size()<<endl;
    for (int i = 0; i < cnt.size(); ++i)
    {
        cout <<cnt[i]+1<<" ";
    }cout <<endl;
}

Compilation message (stderr)

pastiri.cpp: In function 'int main()':
pastiri.cpp:120:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  120 |     for (int i = 0; i < cnt.size(); ++i)
      |                     ~~^~~~~~~~~~~~

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