Submission #1156940

#	Time	Username	Problem	Language	Result	Execution time	Memory
1156940		SmuggingSpun	Magic Tree (CEOI19_magictree)	C++20	6 / 100	1451 ms	175176 KiB

magictree

#include<bits/stdc++.h>
#define taskname "B"
using namespace std;
typedef long long ll;
template<class T>void maximize(T& a, T b){
	if(a < b){
		a = b;
	}
}
const int lim = 1e5 + 5;
int n, m, k, parent[lim], vertex[lim], day[lim], weight[lim];
vector<int>g[lim];
namespace sub1{
	void solve(){
		vector<int>low(n + 1), tail(n + 1);
		int euler = -1;
		auto dfs = [&] (auto&& self, int s) -> void{
			low[s] = ++euler;
			for(int& d : g[s]){
				self(self, d);
			}	
			tail[s] = euler;
		};
		dfs(dfs, 1);
		vector<pair<int, int>>fruit(n, make_pair(-1, 0));
		for(int i = 1; i <= m; i++){
			fruit[low[vertex[i]]] = make_pair(day[i] - 1, weight[i]);
		}
		vector<vector<ll>>f(k, vector<ll>(1 << n, -1));
		auto dp = [&] (auto&& self, int p, int mask) -> ll{
			if(p == k){
				return 0;
			}	
			ll& ans = f[p][mask];
			if(ans != -1){
				return ans;
			}
			ans = self(self, p + 1, mask);
			for(int i = 2; i <= n; i++){
				if(1 << low[i] & mask){
					int nxt = mask;
					ll add = 0;
					for(int j = low[i]; j <= tail[i]; j++){
						if(1 << j & nxt){
							nxt ^= 1 << j;
							if(fruit[j].first == p){
								add += fruit[j].second;
							}
						}
					}
					maximize(ans, self(self, p, nxt) + add);
				}
			}
			return ans;
		};
		cout << dp(dp, 0, (1 << n) - 1);
	}
}
int main(){
	ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
	if(fopen(taskname".inp", "r")){
		freopen(taskname".inp", "r", stdin);
	}
	cin >> n >> m >> k;
	for(int i = 2; i <= n; i++){
		cin >> parent[i];
		g[parent[i]].emplace_back(i);
	}
	for(int i = 1; i <= m; i++){
		cin >> vertex[i] >> day[i] >> weight[i];
	}
	if(max(n, k) <= 20){
		sub1::solve();
	}
}

Compilation message (stderr)

magictree.cpp: In function 'int main()':
magictree.cpp:62:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   62 |                 freopen(taskname".inp", "r", stdin);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 6 / 6
• Subtask 2: 0 / 3
• Subtask 3: 0 / 11
• Subtask 4: 0 / 12
• Subtask 5: 0 / 16
• Subtask 6: 0 / 13
• Subtask 7: 0 / 22
• Subtask 8: 0 / 17