Submission #970911

#	Time	Username	Problem	Language	Result	Execution time	Memory
970911		vjudge1	Fireworks (APIO16_fireworks)	C++14	7 / 100	87 ms	197164 KiB

fireworks

#include<bits/stdc++.h>

using namespace std;

#define int long long

const int N=5000+10, inf=1e18;
int n, m, f[N][N], d[N];
vector<int> vals;
vector<pair<int, int>> g[N];

void pre_dfs(int u){
   for (auto &e:g[u]){
      d[e.first]=d[u]+e.second;
      pre_dfs(e.first);
   }
}

void dfs(int u){
   if (g[u].empty()){
      f[u][lower_bound(vals.begin(), vals.end(), d[u])-vals.begin()]=0;
      return;
   }
   for (int i=0; i<N; ++i) f[u][i]=0;
   for (auto &e:g[u]){
      int v=e.first, w=e.second;
      dfs(v);
      deque<int> dq;
      for (int i=1, j=1; i<(int)vals.size(); ++i){
         while (dq.size() && dq.front()<i) dq.pop_front();
         while (j<(int)vals.size() && vals[j]-vals[i]<=w){
            while (dq.size() && f[v][dq.back()]+vals[dq.back()]>=f[v][j]+vals[j]) dq.pop_back();
            dq.push_back(j);
            ++j;
         }
         f[v][i]=min(f[v][i], f[v][dq.front()]+vals[dq.front()]-vals[i]);
      }
      for (int i=2; i<(int)vals.size(); ++i) f[v][i]=min(f[v][i], f[v][i-1]+vals[i]-vals[i-1]);
      for (int i=1; i<(int)vals.size(); ++i) f[u][i]=min(inf, f[u][i]+f[v][i]);
   }
}

int32_t main(){
   ios_base::sync_with_stdio(false);
   cin.tie(nullptr);
   cin >> n >> m;
   if (n==1){
      vector<int> v;
      for (int i=2; i<=n+m; ++i){
         int p, c; cin >> p >> c;
         v.push_back(c);
      }
      sort(v.begin(), v.end());
      int val=v[m/2], ans=0;
      for (auto &i:v) ans+=abs(i-val);
      cout << ans << '\n';
      return 0;
   }
   for (int i=2; i<=m+n; ++i){
      int p, c; cin >> p >> c;
      g[p].emplace_back(i, c);
   }
   for (int i=0; i<N; ++i) for (int j=0; j<N; ++j) f[i][j]=inf;
   pre_dfs(1);
   vals.push_back(-1);
   for (int i=n+1; i<=n+m; ++i) vals.push_back(d[i]);
   sort(vals.begin(), vals.end()); vals.resize(unique(vals.begin(), vals.end())-vals.begin());
   dfs(1);
   cout << *min_element(f[1]+1, f[1]+(int)vals.size()) << '\n';
   return 0;
}

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