Submission #1022662

#	Time	Username	Problem	Language	Result	Execution time	Memory
1022662		stefanopulos	Pastiri (COI20_pastiri)	C++17	0 / 100	322 ms	68744 KiB

pastiri

#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <bits/stdc++.h>
 
using namespace std;
using namespace __gnu_pbds;
 
typedef long long ll;
typedef long double ldb;
 
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef pair<ldb,ldb> pdd;

#define ff(i,a,b) for(int i = a; i <= b; i++)
#define fb(i,b,a) for(int i = b; i >= a; i--)
#define trav(a,x) for(auto& a : x)
 
#define sz(a) (int)(a).size()
#define fi first
#define se second
#define pb push_back
#define lb lower_bound
#define ub upper_bound
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
 
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

template<typename T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

// os.order_of_key(k) the number of elements in the os less than k
// *os.find_by_order(k)  print the k-th smallest number in os(0-based)

const int mod = 1000000007;
const int inf = 1e9 + 5;
const int mxN = 500005; 

int n, k;

vector<int> g[mxN];
bool mark[mxN];

int d[mxN];

int id[mxN];
bool cmp(int i, int j){
    return d[i] > d[j];
}

bool los[mxN];

bool dbr[mxN];
bool dodat[mxN];

vector<int> vec[mxN];
vector<int> svi[mxN];

int r = 0;
void dfs(int v, int p, int duz){
    if(duz == 0){
        if(mark[v]){
            vec[v].pb(r);
            svi[r].pb(v);
        }
        return;
    }
 
    for(auto u : g[v]){
        if(u != p){
            dfs(u, v, duz - 1);
        }
    }
 
}

int main(){
    cin.tie(0)->sync_with_stdio(0);

    cin >> n >> k;
    
    vector<pii> edge;
    ff(i,1,n - 1){
        int u, v;
        cin >> u >> v;
        g[u].pb(v);
        g[v].pb(u);
        edge.pb({u, v});
    }

    ff(i,1,k){
        int X;
        cin >> X;
        mark[X] = 1;
    }

    ff(i,1,n)d[i] = inf;

    queue<int> que;
    ff(i,1,n){
        if(mark[i] == 1){
            que.push(i);
            d[i] = 0;
        }
    }

    while(sz(que)){
        int v = que.front(); que.pop();
        for(auto u : g[v]){
            if(d[u] == inf){
                d[u] = d[v] + 1;
                que.push(u);
            }
        }
    }

    ff(i,1,n)id[i] = i;
    sort(id + 1, id + n + 1, cmp);
 
    ff(i,1,n){
        int u = id[i];
 
        int br = 0; bool ok = 0;
        for(auto c : g[u]){
            if(!los[c]){
                br += (d[c] == d[u] - 1);
                ok |= (d[c] == d[u] + 1);
            }
        }
 
        if(br == 1 || ok == 1){
            los[u] = 1;
            continue;
        }

        r = u; dfs(u, -1, d[u]);

    }

    vector<int> res;
    ff(i,1,n){
        if(mark[i] && sz(vec[i]) == 1){
            int X = vec[i][0];
            if(dodat[X] == 0){
                for(auto c : svi[X])dbr[c] = 1;
                res.pb(X); dodat[X] = 1;
            }
        }
    }

    ff(i,1,n){
        if(mark[i] && !dbr[i]){
            int X = vec[i][0]; 
            if(dodat[X] == 0){
                for(auto c : svi[X])dbr[c] = 1;
                res.pb(X); dodat[X] = 1;
            }
        }
    }
 
    cout << sz(res) << '\n';
    for(auto c : res)cout << c << " ";
    cout << '\n';

    return 0;
}
/*

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// probati bojenje sahovski
*/
 
 
 
 
 

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