Submission #421388

#	Time	Username	Problem	Language	Result	Execution time	Memory
421388		codebuster_10	Railway (BOI17_railway)	C++17	100 / 100	469 ms	111648 KiB

railway

#include <bits/stdc++.h>

using namespace std ;

#define int int64_t //be careful about this 
#define endl "\n"
#define f(i,a,b) for(int i=int(a);i<int(b);++i)

#define pr pair
#define ar array
#define fr first
#define sc second
#define vt vector
#define pb push_back
#define eb emplace_back
#define LB lower_bound  
#define UB upper_bound
#define PQ priority_queue

#define sz(x) ((int)(x).size())
#define all(a) (a).begin(),(a).end()
#define allr(a) (a).rbegin(),(a).rend()
#define mem(a,b) memset(a, b, sizeof(a))

template<class A> void rd(vt<A>& v);
template<class T> void rd(T& x){ cin >> x; }
template<class H, class... T> void rd(H& h, T&... t) { rd(h) ; rd(t...) ;}
template<class A> void rd(vt<A>& x) { for(auto& a : x) rd(a) ;}

template<class T> bool ckmin(T& a, const T& b) { return b < a ? a = b, 1 : 0; }
template<class T> bool ckmax(T& a, const T& b) { return a < b ? a = b, 1 : 0; }

template<typename T>
void __p(T a) {
  cout<<a; 
}
template<typename T, typename F>
void __p(pair<T, F> a) {
  cout<<"{";
  __p(a.first);
  cout<<",";
  __p(a.second);
  cout<<"}\n"; 
}
template<typename T>
void __p(std::vector<T> a) {
  cout<<"{";
  for(auto it=a.begin(); it<a.end(); it++)
    __p(*it),cout<<",}\n"[it+1==a.end()]; 
}
template<typename T, typename ...Arg>
void __p(T a1, Arg ...a) {
  __p(a1);
  __p(a...);
}
template<typename Arg1>
void __f(const char *name, Arg1 &&arg1) {
  cout<<name<<" : ";
  __p(arg1);
  cout<<endl;
}
template<typename Arg1, typename ... Args>
void __f(const char *names, Arg1 &&arg1, Args &&... args) {
  int bracket=0,i=0;
  for(;; i++)
    if(names[i]==','&&bracket==0)
      break;
    else if(names[i]=='(')
      bracket++;
    else if(names[i]==')')
      bracket--;
  const char *comma=names+i;
  cout.write(names,comma-names)<<" : ";
  __p(arg1);
  cout<<" | ";
  __f(comma+1,args...);
}

void setIO(string s = "") {
  ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0); 
  cin.exceptions(cin.failbit); 
	cout.precision(15);	cout << fixed;
  if(sz(s)){
  	freopen((s+".in").c_str(),"r",stdin);
  	freopen((s+".out").c_str(),"w",stdout);
  }
}































struct LCA {
  int N, timer = 0, LOG ; 
  vector< vector<int> > up, dis, max_edge ;
  vector< vector<array<int,2> > > adj ;
  vector<int> tin, tout, depth ;
 
  void init(int _N) { 
    N = _N ; LOG = log2(N) + 5 ; 
    adj.resize(N) ; 
    up.resize(N, vector<int> (LOG)) ;
    dis.resize(N, vector<int> (LOG)) ;
    max_edge.resize(N, vector<int> (LOG)) ;
    tin = tout = depth = vector<int> (N) ; 
  }
 
  void ae(int x, int y,int w = 1) { // add edge
    adj[x].push_back({y,w}), adj[y].push_back({x,w}); 
  }
 
  void dfs(int v, int p, int w){
    tin[v] = ++timer;
    up[v][0] = p;
    dis[v][0] = w ;
    max_edge[v][0] = w ;
    for(int i = 1; i < LOG; i++){
      up[v][i] = up[up[v][i-1]][i-1] ;
      dis[v][i] = dis[v][i-1] + dis[up[v][i-1]][i-1] ;
      max_edge[v][i] = max(max_edge[v][i-1],max_edge[up[v][i-1]][i-1]) ;
    } 
    for(auto arr:adj[v]){
    	int u = arr[0], w = arr[1];
    	if(u != p){
      	depth[u] = depth[v] + 1 ; dfs(u,v,w) ;
      }
    }
    tout[v] = ++timer;
  }
 
  void gen(int R = 0) { 
    depth[R] = 0 ;
    dfs(R,R,0); 
  }
 
  bool is_ancestor(int u, int v){
    return tin[u] <= tin[v] && tout[u] >= tout[v];
  }
 
  int lca(int u, int v){
    if( is_ancestor(u,v) )  return u;
    if( is_ancestor(v,u) )  return v;
    for(int i=LOG-1;i>=0;--i) {
      if( !is_ancestor(up[u][i],v) ){
        u = up[u][i] ;
      } 
    }
    return up[u][0];
  }
 
  int dist(int u, int v) {
    return depth[u] + depth[v] - 2*depth[lca(u,v)]; 
  }
	
	int weighted_dist(int u,int v){
		int temp = lca(u,v);
		int x1 = kth_ancestor_weighted_dist(u,depth[u] - depth[temp]);
		int x2 = kth_ancestor_weighted_dist(v,depth[v] - depth[temp]);
		return x1 + x2 ;
	}
	
	int weighted_max_edge(int u,int v){
		int temp = lca(u,v);
		int x1 = kth_ancestor_weighted_max_edge(u,depth[u] - depth[temp]);
		int x2 = kth_ancestor_weighted_max_edge(v,depth[v] - depth[temp]);
		return max(x1, x2) ;
	}
  int kth_ancestor(int i,int k){
    if(depth[i] < k) return int(-1) ;
    for(int j = LOG - 1; j >= 0; --j){
      if( (int(1) << j) <= k ){
        k -= (int(1) << j) ; i = up[i][j] ; 
      }
    }
    return i ;
  }
  int kth_ancestor_weighted_dist(int i,int k){
  	if(depth[i] < k) return int(-1) ;
  	int ans = 0 ;
    for(int j = LOG - 1; j >= 0; --j){
      if( (int(1) << j) <= k ){
        k -= (int(1) << j) ;
        ans += dis[i][j] ;
        i = up[i][j] ; 
      }
    }
    return ans ;
  }
  int kth_ancestor_weighted_max_edge(int i,int k){
  	if(depth[i] < k) return int(-1) ;
  	int ans = 0 ;
    for(int j = LOG - 1; j >= 0; --j){
      if( (int(1) << j) <= k ){
        k -= (int(1) << j) ;
        ckmax(ans,max_edge[i][j]) ;
        i = up[i][j] ; 
      }
    }
    return ans ;
  }
  int d(int i){
  	return depth[i];
  }
};

LCA tree;

const int MAX_N = 1e5 + 7;
vector<int> g[MAX_N], st(MAX_N), en(MAX_N), par(MAX_N);
int timer = 1;
void dfs(int i, int p){
  st[i] = timer++ ;
  par[i] = p;
  for(auto j:g[i]) if(j!=p){
    dfs(j, i);
  }
  en[i] = timer - 1 ;
}

template <class T, int ...Ns> struct BIT {
	T val = 0; void upd(T v) { val += v; }
	T query() { return val; }
};
template <class T, int N, int... Ns> struct BIT<T, N, Ns...> {
	BIT<T,Ns...> bit[N+1];
	template<typename... Args> void upd(int pos, Args... args) { assert(pos > 0);
		for (; pos<=N; pos+=pos&-pos) bit[pos].upd(args...); }
	template<typename... Args> T sum(int r, Args... args) {
		T res=0; for (;r;r-=r&-r) res += bit[r].query(args...); 
		return res; }
	template<typename... Args> T query(int l, int r, Args... 
		args) { return sum(r,args...)-sum(l-1,args...); }
}; 

BIT<int,MAX_N> bit;

signed main(){
  setIO();
  int n,m,k; rd(n,m,k);
  tree.init(n);
  vt<ar<int,2>> edges;
  
  f(_,0,n-1){
  	int u,v; rd(u,v);
  	edges.pb({--u,--v});
  	tree.ae(u,v);
  	g[u].pb(v);
  	g[v].pb(u);
  	
  }
  tree.gen(0);
  dfs(0,0);
  
	set<pr<int,int>> node[n];
	f(j,0,m){
		int SZ; rd(SZ);
		vt<int> a(SZ);
		for(auto& i : a) rd(i),--i;
		int x = a[0];
		for(auto i : a){
			x = tree.lca(i,x);
			bit.upd(st[i],1);// ude bit to get end points.
		}
		int d = tree.d(x);
		for(auto i : a){
			if(bit.query(st[i],en[i]) == 1){
				node[i].insert({-d,j});
			}
		}
		for(auto i : a) bit.upd(st[i],-1);
	}
	
	vt<int> value(n);
	
	function<void(int)> small_to_large = [&](int i){
		for(auto j : g[i]) if(j != par[i]){
			small_to_large(j);
			// merge j and i;
			if( sz(node[j]) > sz(node[i]) ) node[i].swap(node[j]);
			for(auto p : node[j]) node[i].insert(p);
			node[j].clear();
		}
		int d = -1 * tree.d(i);
		while(sz(node[i]) && node[i].begin()->first <= d){
			node[i].erase(node[i].begin());
		}
		value[i] = sz(node[i]);
	};
	small_to_large(0);
	
	set<pr<int,int>> good;
	f(i,0,n) if(value[i] >= k) good.insert({i,par[i]});
	
	vt<int> ans;
	f(i,0,n-1){
		auto [u,v] = edges[i];
		if(good.count({u,v}) || good.count({v,u})) ans.pb(i);
	}
	
	cout << sz(ans) << endl;
	for(auto i : ans) cout << i + 1 << " " ;
	
}

Compilation message (stderr)

railway.cpp: In function 'void setIO(std::string)':
railway.cpp:84:11: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   84 |    freopen((s+".in").c_str(),"r",stdin);
      |    ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
railway.cpp:85:11: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   85 |    freopen((s+".out").c_str(),"w",stdout);
      |    ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 8 / 8
• Subtask 2: 15 / 15
• Subtask 3: 7 / 7
• Subtask 4: 29 / 29
• Subtask 5: 16 / 16
• Subtask 6: 25 / 25