Submission #1076929

#	Time	Username	Problem	Language	Result	Execution time	Memory
1076929		Andrei_ierdnA	Tortoise (CEOI21_tortoise)	C++17	8 / 100	1 ms	460 KiB

tortoise

/// courtesy of bleahbleah
 
#include <bits/stdc++.h>
#define all(x) (x).begin(),(x).end()
using namespace std;
 
//#ifndef DLOCAL
//   #define cin fin
//   #define cout fout
//   ifstream cin(".in");
//   ofstream cout(".out");
//#endif
 
using ll = long long;
using ld = long double;
 
#define int ll
#define sz(x) ((int)(x).size())
 
using pii = pair<int,int>;
using tii = tuple<int,int,int>;
 
const int nmax = 5e5 + 5;
 
int Ld[nmax], Rd[nmax];
int v[nmax];
 
bool possible(multiset<int> s) {
   int last = -1, timer = 0;
   for(auto x : s) {
      if(last == -1) {
         timer += x - 1;
      }
      else {
         if(Ld[last] != Ld[x] || Rd[last] != Rd[x])
            timer += x - last;
         else timer += min(last - Ld[last] + x - Ld[x], Rd[last] - last + Rd[x] - x);
      }
      if(timer > 2 * (x - 1)) { return 0; }
      last = x;
      //cerr << timer << '\n';
   }
   //cerr << '\n';
   //for(auto x: s) cerr << x << ' '; cerr << '\n';
   //cerr << "ok\n";
   return 1;
}
 
signed main() {
   cin.tie(0) -> sync_with_stdio(0);
   int n;
   cin >> n;
   
   ll cost = 0;
   for(int i = 1; i <= n; i++)
      cin >> v[i], cost += (v[i] != -1? v[i] : 0);
   for(int lst = -1e9 - 5, i = 1; i <= n; i++) {
      if(v[i] == -1) lst = i;
      else Ld[i] = lst;
   }
   for(int lst = 1e9 + 5, i = n; i > 0; i--) {
      if(v[i] == -1) lst = i;
      else Rd[i] = lst;
   }
   
   vector<vector<int>> idxs(n + 2);
   multiset<int> sofar;
   
   for(int i = n; i >= 1; i--) {
      if(v[i] == -1) continue;
      idxs[min(Rd[i] - i, i - Ld[i])].emplace_back(i);
   }
   
   
   for(int i = 0; i < 1; i++) {
      for(auto &T : idxs) {
         for(auto x : T) {
            while(v[x] > 0) {
               sofar.emplace(x);
               if(possible(sofar)) v[x]--;
               else {
                  sofar.erase(sofar.find(x));
                  break;
               }
            }
         }
      }
   }
   
   //for(int i = 1; i <= n; i++) cerr << v[i] << ' ';
   //cerr << '\n';
   
   cout << cost - sz(sofar) << '\n';
 
}
 
/**
      Töte es durch genaue Untersuchung\Töte es kann es nur noch schlimmer machen\Es lässt es irgendwie atmen
--
*/ 

• Subtask 1: 8 / 8
• Subtask 2: 0 / 10
• Subtask 3: 0 / 30
• Subtask 4: 0 / 25
• Subtask 5: 0 / 27