Submission #389080

#	Time	Username	Problem	Language	Result	Execution time	Memory
389080		Return_0	Cat in a tree (BOI17_catinatree)	C++17	100 / 100	337 ms	41376 KiB

catinatree

#pragma GCC optimize("Ofast,unroll-loops")
// #pragma comment(linker, "/stack:200000000")
// #pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,avx2,fma,tune=native")

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace std;
using namespace __gnu_pbds;

typedef int ll; typedef long long lol;
typedef long double ld;
typedef pair <ll, ll> pll;

#ifdef SINA
#define dbg(...) __f(#__VA_ARGS__, __VA_ARGS__)
template <typename Arg1> void __f(const char* name, Arg1&& arg1) { cout << name << " : " << arg1 << std::endl; }
template <typename Arg1, typename... Args> void __f (const char* names, Arg1&& arg1, Args&&... args) {
	const char* comma = strchr(names + 1, ',');cout.write(names, comma - names) << " : " << arg1<<" | ";__f(comma+1, args...); }
#define dbg2(x, j, n) cout<< #x << " : "; output((j), (n), x, 1); cout.flush();
#else
#define dbg(...) 0
#define dbg2(x, j, n) 0
#endif
#define SZ(x) ((ll)((x).size()))
#define File(s, t) freopen(s ".txt", "r", stdin); freopen(t ".txt", "w", stdout);
#define input(j, n, a) for (int _i = (j); _i < (n)+(j); _i++) cin>> a[_i];
#define output(j, n, a, t) for (int _i = (j); _i < (n)+(j); _i++) cout<< a[_i] << (((t) && _i != (n)+(j)-1)? ' ' : '\n');
#define kill(x) return cout<< (x) << endl, 0
#define cl const ll
#define fr first
#define sc second
#define lc (v << 1)
#define rc (lc | 1)
#define mid ((l + r) >> 1)
#define All(x) (x).begin(), (x).end()

cl inf = sizeof(ll) == 4 ? (1e9 + 10) : (3e18), mod = 1e9 + 7, MOD = 998244353;

template <class A,class B> ostream& operator << (ostream& out,const pair<A,B>&a){return out<<'('<<a.first<<", "<<a.second<<')';}
template <class A> ostream& operator << (ostream& out, const vector<A> &a) {
	out<< '['; for (int i = -1; ++i < int(a.size());) out<< a[i] << (i + 1 < int(a.size()) ? ", " : ""); return out<<']'; }
template <class T, typename _t = less <T> > using Tree = tree <T, null_type, _t, rb_tree_tag, tree_order_statistics_node_update>;

cl N = 2e5 + 7, lg = 18;

struct segtree {
	ll l, r;
	lol mx, lz;
	segtree *lt, *rt;
	inline segtree (cl &L = 1, cl &R = N - 2) : l(L), r(R), mx(0), lz(0) {}

	void build () {
		if (l == r) return;
		lt = new segtree (l, mid);
		rt = new segtree (mid + 1, r);
		lt->build();
		rt->build();
	}

	inline void push (const lol &x) {   mx += x; lz += x;    }
	inline void shift () {  lt->push(lz);   rt->push(lz);   lz = 0; }

	void upd (cl &ql, cl &qr, cl &x) {
		if (r < ql || qr < l)   return;
		if (ql <= l && r <= qr) {
			push(x);
			return;
		}
		shift();
		lt->upd(ql, qr, x);
		rt->upd(ql, qr, x);
		mx = max(lt->mx, rt->mx);
	}

	ll ask () {
		if (l == r) return l;
		shift();
		if (mx == lt->mx) return lt->ask();
		return rt->ask();
	}

	lol ask2 (cl &ql, cl & qr) {
		if (r < ql || qr < l) return -inf;
		if (ql <= l && r <= qr) return mx;
		shift();
		return max(lt->ask2(ql, qr), rt->ask2(ql, qr));
	}
} seg;

ll h [N], par [N], tin [N], rtin [N], tout [N], T, n, D, ans;
vector <ll> adj [N];

void DFS (cl &v = 0, cl &pr = -1) {
	tin[v] = ++T;
	rtin[T] = v;
	par[v] = pr;
	for (auto &u : adj[v]) if (u != pr) h[u] = h[v] + 1, DFS(u, v);
	seg.upd(tin[v], tin[v], h[v]);
	tout[v] = T;
}

int main ()
{
	ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);

	cin>> n >> D;
	for (ll i = 1, v; i < n; i++) {
		cin>> v;
		adj[v].push_back(i);
	}

	seg.r = n; seg.build();
	DFS();

	for (ll v; seg.mx >= 0;) {
		v = rtin[seg.ask()];
		ans++;
		for (ll i = 0; ~v && seg.ask2(tin[v], tout[v]) + i - h[v] < D; i++, v = par[v]) seg.upd(tin[v], tout[v], -N);
	}

	cout<< ans << endl;

	cerr<< "\nTime elapsed: " << 1000 * clock() / CLOCKS_PER_SEC << "ms\n";

	return 0;
}
/*
4 3
0
0
1

<+
*/

• Subtask 1: 11 / 11
• Subtask 2: 40 / 40
• Subtask 3: 49 / 49