Submission #651862

#	Time	Username	Problem	Language	Result	Execution time	Memory
651862		kym	Pastiri (COI20_pastiri)	C++14	8 / 100	676 ms	159024 KiB

pastiri

#include <bits/stdc++.h>
using namespace std;
#define int ll 
#define FOR(i,s,e) for(ll i = s; i <= (ll)e; ++i)
#define DEC(i,s,e) for(ll i = s; i >= (ll)e; --i)
#define IAMSPEED ios_base::sync_with_stdio(false); cin.tie(0);
#ifdef LOCAL
#define db(x) cerr << #x << "=" << x << "\n"
#define db2(x, y) cerr << #x << "=" << x << " , " << #y << "=" << y << "\n"
#define db3(a,b,c) cerr<<#a<<"="<<a<<","<<#b<<"="<<b<<","<<#c<<"="<<c<<"\n"
#define dbv(v) cerr << #v << ":"; for (auto ite : v) cerr << ite << ' '; cerr <<"\n"
#define dbvp(v) cerr << #v << ":"; for (auto ite : v) cerr << "{"  << ite.f << ',' << ite.s << "} "; cerr << "\n"
#define dba(a,ss,ee) cerr << #a << ":"; FOR(ite,ss,ee) cerr << a[ite] << ' '; cerr << "\n"
#else
#define db(x)
#define db2(x,y)
#define db3(a,b,c)
#define dbv(v)
#define dbvp(v)
#define dba(a,ss,ee)
#endif
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
#define ll long long 
#define pb push_back
#define eb emplace_back
#define all(x) (x).begin(), (x).end()
#define f first 	
#define s second
#define g0(x) get<0>(x)
#define g1(x) get<1>(x)
#define g2(x) get<2>(x)
#define g3(x) get<3>(x)
#define reach cerr << "LINE: " << __LINE__ << "\n";
typedef pair <ll, ll> pi;
typedef tuple<ll,ll,ll> ti3;
typedef tuple<ll,ll,ll,ll> ti4;
ll rand(ll a, ll b) { return a + rng() % (b-a+1); }
const int MOD = 1e9 + 7;
const int inf = (int)1e9 + 500;
const long long oo = (ll)1e18 + 500;
template <typename T> bool chmax(T& a, const T b) { return a<b ? a = b, 1 : 0; }
template <typename T> bool chmin(T& a, const T b) { return a>b ? a = b, 1 : 0; }
const int MAXN = 500005;
int n,k;
vector<int> V[MAXN];
int dist[MAXN]; // dist to nearest sheep
bool done[MAXN];
int depth[MAXN];
int dd[MAXN];
int twok[MAXN][20];

void dfs(int x, int p) {
	twok[x][0]=p;
	FOR(i,1,19) {
		if(twok[x][i-1]==-1)break;
		twok[x][i]=twok[twok[x][i-1]][i-1];
	}
	for(auto v:V[x])if(v^p) {
		depth[v]=depth[x]+1;
		dfs(v,x);
	}
}

int32_t main() 
{
	IAMSPEED
	memset(twok,-1,sizeof twok);
	cin >> n >> k;
	queue<int> q;
	vector<int> sheep;
	FOR(i,1,n-1) {
		int a,b; cin >> a >> b;
		V[a].pb(b);
		V[b].pb(a);
	}
	FOR(i,1,k) {
		int x; cin >> x;
		sheep.pb(x);
	}
	FOR(i,0,MAXN-1)dist[i]=oo;
	for(auto i:sheep){
		q.push(i);
		dist[i]=0;
	}
	map<int,vector<int>> mp;
	int pre=0;
	vector<int> out;
	vector<int> push;
	int curdist=0;
	while(q.size()) {
		int x=q.front(); q.pop();
		for(auto v:V[x]){
			if(dist[v] == oo){
				dist[v]=dist[x]+1;
				q.push(v);
			}
		}
		
	}
	dfs(1,-1);
	sort(all(sheep), [](int a, int b) {
		return depth[a] > depth[b];
	});
	FOR(i,0,MAXN-1)dd[i]=oo;
	dba(dist,1,n);
	dba(depth,1,n);
	for(auto sh:sheep) {
		//db(sh);
		dba(done,1,n);
		if(done[sh])continue;
		int cur=sh;
		DEC(i,20,0) {
			if(twok[cur][i] == -1)continue;
			if(dist[twok[cur][i]] != (depth[sh] - depth[twok[cur][i]]))continue;
			cur=twok[cur][i]; // lift it there.
		}
		//put a shephard at cur.
		db2(sh,cur);
		q.push(cur);
		dd[cur]=0;
		out.pb(cur);
		int finaldist=dist[cur];
		while(q.size()) {
			int x=q.front(); q.pop();
			done[cur]=1;
			if(dd[x]==finaldist)continue;
			for(auto v:V[x]) {
				if(dd[v]==oo || dd[v] > dd[x]+1) {
					done[v]=1;
					q.push(v);
					dd[v]=dd[x]+1;
				}
			}
		}
		
	}

	cout << out.size() << '\n';
	for(auto i:out)cout<<i<<' ';
}

Compilation message (stderr)

pastiri.cpp: In function 'int32_t main()':
pastiri.cpp:86:6: warning: unused variable 'pre' [-Wunused-variable]
   86 |  int pre=0;
      |      ^~~
pastiri.cpp:89:6: warning: unused variable 'curdist' [-Wunused-variable]
   89 |  int curdist=0;
      |      ^~~~~~~

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