Submission #1060817

#	Time	Username	Problem	Language	Result	Execution time	Memory
1060817		xjonwang	Railway (BOI17_railway)	C++17	100 / 100	161 ms	47956 KiB

railway

#include <bits/stdc++.h>
using namespace std;

#define ll long long
#define ld long double
#define ar array

#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp> 
using namespace __gnu_pbds;

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

#define vt vector
#define pb push_back
#define all(c) (c).begin(), (c).end()
#define sz(x) (int)(x).size()
#define pll pair<ll, ll>
#define pii pair<int, int>
#define f first
#define s second

#define F_OR(i, a, b, s) for (int i=(a); (s)>0?i<(b):i>(b); i+=(s))
#define F_OR1(e) F_OR(i, 0, e, 1)
#define F_OR2(i, e) F_OR(i, 0, e, 1)
#define F_OR3(i, b, e) F_OR(i, b, e, 1)
#define F_OR4(i, b, e, s) F_OR(i, b, e, s)
#define GET5(a, b, c, d, e, ...) e
#define F_ORC(...) GET5(__VA_ARGS__, F_OR4, F_OR3, F_OR2, F_OR1)
#define FOR(...) F_ORC(__VA_ARGS__)(__VA_ARGS__)
#define EACH(x, a) for (auto& x: a)

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

ll FIRSTTRUE(function<bool(ll)> f, ll lb, ll rb) {
	while(lb<rb) {
		ll mb=(lb+rb)/2;
		f(mb)?rb=mb:lb=mb+1; 
	} 
	return lb;
}
ll LASTTRUE(function<bool(ll)> f, ll lb, ll rb) {
	while(lb<rb) {
		ll mb=(lb+rb+1)/2;
		f(mb)?lb=mb:rb=mb-1; 
	} 
	return lb;
}

template<class A> void read(vt<A>& v);
template<class A, size_t S> void read(ar<A, S>& a);
template<class A, class B> void read(pair<A, B>& x);
template<class T> void read(T& x) {
	cin >> x;
}
void read(double& d) {
	string t;
	read(t);
	d=stod(t);
}
void read(long double& d) {
	string t;
	read(t);
	d=stold(t);
}
template<class H, class... T> void read(H& h, T&... t) {
	read(h);
	read(t...);
}
template<class A> void read(vt<A>& x) {
	EACH(a, x)
		read(a);
}
template<class A, size_t S> void read(array<A, S>& x) {
	EACH(a, x)
		read(a);
}
template<class A, class B> void read(pair<A, B>& x) {
	cin >> x.first >> x.second;
}


string to_string(char c) {
	return string(1, c);
}
string to_string(bool b) {
	return b?"true":"false";
}
string to_string(const char* s) {
	return string(s);
}
string to_string(string s) {
	return s;
}
string to_string(vt<bool> v) {
	string res;
	FOR(sz(v))
		res+=char('0'+v[i]);
	return res;
}

template<size_t S> string to_string(bitset<S> b) {
	string res;
	FOR(S)
		res+=char('0'+b[i]);
	return res;
}
template<class T> string to_string(T v) {
    bool f=1;
    string res;
    EACH(x, v) {
		if(!f)
			res+=' ';
		f=0;
		res+=to_string(x);
	}
    return res;
}
template<class A, class B> string to_string(pair<A, B>& x) {
	return to_string(x.first) + ' ' + to_string(x.second);
}

template<class A> void write(A x) {
	cout << to_string(x);
}
template<class H, class... T> void write(const H& h, const T&... t) { 
	write(h);
	write(t...);
}
void print() {
	write("\n");
}
template<class H, class... T> void print(const H& h, const T&... t) { 
	write(h);
	if(sizeof...(t))
		write(' ');
	print(t...);
}

int n, m, h;
vt<vt<pii>> adj;
vt<vt<int>> up, rem;
vt<int> d, ans;
vt<set<int>> add;

void dfs(int v, int p=-1) {
	d[v]=v ? d[p]+1 : 0;
	up[v][0]=p;
	for (auto& [u, _] : adj[v]) if (u!=p) dfs(u, v);
}
int lift(int x, int k) {
	FOR(18) if (x!=-1 && k&(1<<i)) x=up[x][i];
	return x;
}
int lca(vt<int> v) {
	int md=INT_MAX;
	EACH(x, v) umin(md, d[x]);
	EACH(x, v) x=lift(x, d[x]-md);
	auto check=[&](vt<int>& v) {
		FOR(i, 1, sz(v)) if (v[i]!=v[i-1]) return false;
		return true;
	};
	auto apply=[&](int k, vt<int>& v) {
		EACH(x, v) if (up[x][k]==-1) return false;
		EACH(x, v) x=up[x][k];
		return true;
	};
	if (check(v)) return v[0];
	vt<int> t=v;
	FOR(i, 17, -1, -1) {
		if (apply(i, t) && !check(t)) apply(i, v);
		t=v;
	}
	return up[v[0]][0];
}
void dfs2(int v, int e=-1, int p=-1) {
	for (auto& [u, e] : adj[v]) {
		if (u==p) continue;
		dfs2(u, e, v);
		if (sz(add[v])<sz(add[u])) swap(add[v], add[u]);
		EACH(x, add[u]) add[v].insert(x);
	}
	EACH(x, rem[v]) add[v].erase(x);
	if (sz(add[v])>=h) ans.pb(e+1);
}

int main() {
	ios::sync_with_stdio(0);
	cin.tie(0);
	read(n, m, h);
	adj.resize(n), d.resize(n), add.resize(n), rem.resize(n), up.assign(n, vt<int>(18, -1));
	int x, y;
	FOR(n-1) {
		read(x, y); --x, --y;
		adj[x].pb({y, i});
		adj[y].pb({x, i});
	}
	dfs(0);
	FOR(i, 1, 18) FOR(j, n) if (up[j][i-1]!=-1) up[j][i]=up[up[j][i-1]][i-1];
	FOR(m) {
		read(x);
		vt<int> v(x); read(v);
		EACH(x, v) add[--x].insert(i);
		rem[lca(v)].pb(i);
	}
	dfs2(0);
	print(sz(ans));
	sort(all(ans));
	print(ans);
}

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