Submission #1171633

#	Time	Username	Problem	Language	Result	Execution time	Memory
1171633		Zero_OP	Relay Marathon (NOI20_relaymarathon)	C++20	17 / 100	6092 ms	96208 KiB

RelayMarathon

#include <bits/stdc++.h>

using namespace std;

#define FOR(i, l, r) for(int i = (l); i < (r); ++i)
#define ROF(i, r, l) for(int i = (r)-1; i >= (l); --i)

#define mp make_pair
#define mt make_tuple
#define ff first
#define ss second

#define all(v) begin(v), end(v)
#define rall(v) rbegin(v), rend(v)
#define sz(v) (int)v.size()
#define pb push_back
#define eb emplace_back
#define compact(v) v.erase(unique(all(v)), end(v))

#define dbg(x) "[" #x " = " << (x) << "]"

template<typename T>
      bool minimize(T& a, const T& b){
            if(a > b) return a = b, true;
            return false;
      }

template<typename T>
      bool maximize(T& a, const T& b){
            if(a < b) return a = b, true;
            return false;
      }

typedef long long ll;

using db = double;
using ull = unsigned long long;

using pi = pair<int, int>;
using pl = pair<ll, ll>;
using pd = pair<db, db>;

using vi = vector<int>;
using vl = vector<ll>;
using vc = vector<char>;
using vd = vector<db>;
using vb = vector<bool>;

using vpi = vector<pi>;
using vpl = vector<pl>;

void setIO(){
      ios_base::sync_with_stdio(0); cin.tie(0);
#ifdef LOCAL
      freopen("task.inp", "r", stdin);
      freopen("task.out", "w", stdout);
#endif
}

const int MAX = 1e5 + 5;
const int inf = 1e9 + 9;

int N, M, K, A[MAX], cnt_vis[MAX];
vpi adj[MAX];
vector<tuple<int, int, int>> important_pairs;
bool is_special[MAX], done[MAX];
vector<pi> top[MAX];
vpi paths[MAX];;

bool can(int v, int org, int cost){
      if(v == org) return false;
      if(top[v].empty()) {
            top[v].eb(cost, org);
            return true;
      }
      for(auto &[tot, st] : top[v]){
            if(st == org){
                  if(tot > cost){
                        tot = cost;
                        sort(all(top[v]));
                        return true;
                  } else return false;
            }
      }

      if(sz(top[v]) < 4){
            top[v].eb(cost, org);
            sort(all(top[v]));
            return true;
      }

      if(top[v][0].ff > cost){
            top[v][0] = mp(cost, org);
            sort(all(top[v]));
            return true;
      }

      return false;
}

int main(){
      setIO();

      cin >> N >> M >> K;
      FOR(i, 0, M){
            int u, v, w;
            cin >> u >> v >> w;
            adj[u].eb(v, w); adj[v].eb(u, w);
      }

      using node = tuple<int, int, int>;
      priority_queue<node, vector<node>, greater<node>> pq;

      while(K--){
            int u;
            cin >> u;
            is_special[u] = true;
            pq.push(mt(0, u, u));
      }

      while(!pq.empty()){
            int dist, u, org;
            tie(dist, u, org) = pq.top(); pq.pop();

            if(cnt_vis[u] == 50) break;
            ++cnt_vis[u];

            for(auto [v, w] : adj[u]){
                  if(can(v, org, dist + w)){
                        pq.push(mt(dist + w, v, org));
                  }
            }
      }

      vector<tuple<int, int, int>> matches;

      FOR(i, 1, N+1){
            if(is_special[i]){
                  for(auto [cost, org] : top[i]){
                        matches.eb(cost, min(i, org), max(i, org));
//                        cout << dbg(cost) << dbg(i) << dbg(org) << '\n';
                  }
            }
      }

      sort(all(matches)); compact(matches);

      multiset<int> online;
      for(auto [cost, x, y] : matches){
            paths[x].eb(cost, y);
            paths[y].eb(cost, x);
            online.insert(cost);
      }

      int ans = inf;

      for(auto [cost, x, y] : matches){
            online.erase(online.lower_bound(cost));
            for(auto [len, z] : paths[x]) if(z != y) online.erase(online.lower_bound(len));
            for(auto [len, z] : paths[y]) if(z != x) online.erase(online.lower_bound(len));

            if(!online.empty()){
                  minimize(ans, *online.begin() + cost);
            }

            online.insert(cost);
            for(auto [len, z] : paths[x]) if(z != y) online.insert(len);
            for(auto [len, z] : paths[y]) if(z != x) online.insert(len);
      }

      cout << ans << '\n';

      return 0;
}

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