Submission #725757

#	Time	Username	Problem	Language	Result	Execution time	Memory
725757		pavement	Cat in a tree (BOI17_catinatree)	C++17	100 / 100	72 ms	22860 KiB

catinatree

#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;
#define int long long
#define mp make_pair
#define mt make_tuple
#define pb push_back
#define ppb pop_back
#define eb emplace_back
#define g0(a) get<0>(a)
#define g1(a) get<1>(a)
#define g2(a) get<2>(a)
#define g3(a) get<3>(a)
#define g4(a) get<4>(a)
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
using db = double;
using ll = long long;
using ld = long double;
using ii = pair<int, int>;
using iii = tuple<int, int, int>;
using iiii = tuple<int, int, int, int>;
using iiiii = tuple<int, int, int, int, int>;
template<class key, class value = null_type, class cmp = less<key> >
using ordered_set = tree<key, value, cmp, rb_tree_tag, tree_order_statistics_node_update>;

int N, D;
vector<int> adj[200005];

ii dp(int n) {
	int sum = 0;
	bool bad = 0;
	ii tot = mp(0, 0);
	vector<ii> vec;
	for (auto u : adj[n]) {
		auto cur = dp(u);
		cur.first++;
		if (cur.first < D) bad = 1;
		sum += cur.second;
		vec.pb(cur);
	}
	if (!bad) {
		//~ cout << "NODE " << n << ' ' << 0 << ' ' << sum + 1 << '\n';
		return mp(0, sum + 1);
	} else {
		sort(vec.begin(), vec.end());
		tot = mp(vec.back().first, sum - ((int)vec.size() - 1));
		for (int i = (int)vec.size() - 1; i >= 1; i--) {
			if (vec[i].first + vec[i - 1].first >= D) {
				auto cand = mp(vec[i - 1].first, sum - (i - 1));
				if (cand.second > tot.second) tot = cand;
				else if (cand.second == tot.second) tot = max(tot, cand);
			}
		}
		//~ cout << "NODE " << n << ' ' << tot.first << ' ' << tot.second << '\n';
		return tot;
	}
}

main() {
	ios::sync_with_stdio(0);
	cin.tie(0);
	cin >> N >> D;
	for (int i = 1, p; i < N; i++) {
		cin >> p;
		adj[p].pb(i);
	}
	cout << dp(0).second << '\n';
}

Compilation message (stderr)

catinatree.cpp:61:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   61 | main() {
      | ^~~~

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