Submission #890094

#	Time	Username	Problem	Language	Result	Execution time	Memory
890094		vjudge1	Relay Marathon (NOI20_relaymarathon)	C++14	17 / 100	6035 ms	14908 KiB

RelayMarathon

#include<bits/stdc++.h>

using namespace std;

#define int long long
#define all(a) (a).begin(), (a).end()

const int N=1e5+1, MAX_SIZE=6;
int n, m, k;
vector<pair<int, int>> dist[N];
vector<pair<int, int>> g[N];

bool optimize(int idx, pair<int, int> val){
   for (auto &i:dist[idx]) if (i.second==val.second){
      if (i.first>val.first){
         i=val;
         return 1;
      }
      return 0;
   }
   if ((int)dist[idx].size()<MAX_SIZE){
      dist[idx].push_back(val);
      sort(dist[idx].begin(), dist[idx].end());
      return 1;
   }
   if (val.first<dist[idx].back().first){
      dist[idx].push_back(val);
      sort(dist[idx].begin(), dist[idx].end());
      dist[idx].pop_back();
      return 1;
   }
   return 0;
}

bool optimize(int idx, int par, int w){
   bool ans=0;
   for (auto &i:dist[par]){
      ans|=optimize(idx, {i.first+w, i.second});
   }
   return ans;
}

struct cmp{
   bool operator()(const pair<vector<pair<int, int>>, int> &a, const pair<vector<pair<int, int>>, int> &b){
      for (int i=0; i<min<int>(a.first.size(), b.first.size()); ++i) if (a.first[i]!=b.first[i]) return a.first[i]<b.first[i];
      if (a.first.size()!=b.first.size()) return a.first.size()<b.first.size();
      return a.second<b.second;
   }
};

int32_t main(){
   ios_base::sync_with_stdio(false);
   cin.tie(nullptr);
   cin >> n >> m >> k;
   for (int i=1; i<=m; ++i){
      int u, v, w; cin >> u >> v >> w;
      g[u].emplace_back(v, w);
      g[v].emplace_back(u, w);
   }
   priority_queue<pair<vector<pair<int, int>>, int>, vector<pair<vector<pair<int, int>>, int>>, cmp> pq;
   for (int i=1; i<=k; ++i){
      int x; cin >> x;
      dist[x].emplace_back(0, x);
      pq.emplace(dist[x], x);
   }
   while (pq.size()){
      int u=pq.top().second; pq.pop();
      for (auto &e:g[u]){
         int v=e.first, w=e.second;
         if (optimize(v, u, w)) pq.emplace(dist[v], v);
      }
   }
   int ans=1e18;
   set<pair<int, pair<int, int>>> st;
   for (int i=1; i<=n; ++i){
      vector<pair<int, int>> d2;
      for (auto &j:dist[i]){
         int u=i, v=j.second, d=j.first;
         if (d && find(all(dist[v]), pair<int, int>{d, u})!=dist[v].end()){
            st.insert({d, {u, v}});
            st.insert({d, {v, u}});
            d2.emplace_back(d, v);
         }
      }
      dist[i].swap(d2);
   }
   for (int i=1; i<=n; ++i){
      int u=i;
      for (auto &j:dist[i]){
         int v=j.second;
         for (auto &t:dist[u]){
            st.erase({t.first, {u, t.second}});
            st.erase({t.first, {t.second, u}});
         }
         for (auto &t:dist[v]){
            st.erase({t.first, {v, t.second}});
            st.erase({t.first, {t.second, v}});
         }
         if (st.size()){
            ans=min(ans, j.first+st.begin()->first);
         }
         for (auto &t:dist[u]){
            st.insert({t.first, {u, t.second}});
            st.insert({t.first, {t.second, u}});
         }
         for (auto &t:dist[v]){
            st.insert({t.first, {v, t.second}});
            st.insert({t.first, {t.second, v}});
         }
      }
   }
   cout << ans;
   return 0;
}

• Subtask 1: 5 / 5
• Subtask 2: 12 / 12
• Subtask 3: 0 / 25
• Subtask 4: 0 / 58