Submission #793373

#	Time	Username	Problem	Language	Result	Execution time	Memory
793373		ToniB	Fireworks (APIO16_fireworks)	C++17	26 / 100	104 ms	7328 KiB

fireworks

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll inf = 2e14;
const int MAXN = 5005;

int n, m;
vector<pair<int, int> > adj[MAXN];
ll val[MAXN], dp[MAXN][MAXN];
vector<ll> walk;

void precalc(int node){
	for(pair<int, int> x : adj[node]){
		val[x.first] = val[node] + x.second;
		precalc(x.first);
	}
	walk.push_back(val[node]);
	walk.push_back(val[node] - 1);
	walk.push_back(val[node] + 1);
}

void dfs(int node){
	if(node >= n){
		for(int i = 0; i < (int)walk.size(); ++i){
			if(val[node] == walk[i]) dp[node][i] = 0;
			else dp[node][i] = inf;
		}
	}
	for(pair<int, int> x : adj[node]){
		dfs(x.first);

		multiset<ll> lo, hi;
		vector<ll> uk ((int)walk.size());

		for(int i = 0; i < (int)walk.size(); ++i){
			lo.insert(dp[x.first][i] - walk[i]);
			uk[i] = walk[i] + *lo.begin();
		}

		int p = (int)walk.size() - 1;
		for(int i = (int)walk.size() - 1; i >= 0; --i){
			hi.insert(dp[x.first][i] + walk[i]);

			while(p > i && x.second + walk[i] - walk[p] < 0){
				assert(hi.find(dp[x.first][p] + walk[p]) != hi.end());
				hi.erase(hi.find(dp[x.first][p] + walk[p]));
				--p;
			}
			uk[i] = min(uk[i], *hi.begin() - walk[i]);
		}

		for(int i = 0; i < (int)walk.size(); ++i){
			dp[node][i] += uk[i];
		}
	}
}

int main(){
	cin >> n >> m;
	for(int i = 1; i < n + m; ++i){
		int p, c;
		cin >> p >> c, --p;
		adj[p].push_back({i, c});
	}
	precalc(0);
	sort(walk.begin(), walk.end());
	walk.erase(unique(walk.begin(), walk.end()), walk.end());

	dfs(0);

	ll ans = dp[0][0];
	for(int i = 1; i < (int)walk.size(); ++i) ans = min(ans, dp[0][i]);

	cout << ans;
	return 0;
}

• Subtask 1: 7 / 7
• Subtask 2: 19 / 19
• Subtask 3: 0 / 29
• Subtask 4: 0 / 45