Submission #1017030

#	Time	Username	Problem	Language	Result	Execution time	Memory
1017030		cadmiumsky	Radio Towers (IOI22_towers)	C++17	0 / 100	4025 ms	6488 KiB

towers

#include "towers.h"

#include <vector>
#include <bits/stdc++.h>
#define all(x) (x).begin(),(x).end()
using namespace std;

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 = 1e5 + 5;
int v[nmax];


void init(signed N, std::vector<signed> H) {
   for(int i = 0; i < N; i++) v[i + 1] = H[i]; 
}

namespace DSU {
   int dsu[nmax], nxt[nmax];
   int mxR[nmax];

   void init(int l, int r) {
      for(int i = l; i <= r; i++) dsu[i] = i, nxt[i] = i + 1;
      return;
   }
   int f(int x) { return x == dsu[x]? x : dsu[x] = f(dsu[x]); }
   void unite(int x, int y) {
      x = f(x);
      y = f(y);
      if(x == y) return;
      if(x > y) swap(x, y);
      dsu[y] = x;
      mxR[x] = max(mxR[x], mxR[y]);
      nxt[x] = nxt[y];
      return;
   }
   int coef(int i, const vector<int>& p) {
      i = f(i);
      return mxR[i] - max(v[p[i]], v[p[nxt[i]]]);
   }
}



signed max_towers(signed L, signed R, signed D) {
   ++L;
   ++R;
   
   vector<int> p;
   for(int i = L; i <= R; i++) {
      if((i == L  || v[i] < v[i - 1]) && (i == R || v[i] < v[i + 1])) p.emplace_back(i);
   }
   
   DSU::init(0, sz(p));
   
   set<pii> heap;
   
   for(int i = 0; i < sz(p) - 1; i++) {
      int mx = v[p[i] + 1];
      for(int j = p[i] + 2; j < p[i + 1]; j++)
         mx = max(mx, v[j]);
      DSU::mxR[i] = mx;
      heap.emplace(mx - max(v[p[i]], v[p[i + 1]]), i);
   }
   
   auto get = [&](int p_) { return pii{DSU::coef(p_, p), p_}; };
      
   cerr << sz(p) << '\n';
      
   while(!heap.empty() && heap.begin() -> first < D) {
      auto [C, i] = *heap.begin();
      heap.erase(heap.begin());
      
      //cerr << C << ' ' << i << '\n';

      i = DSU::f(i);
      int urm = DSU::nxt[i];
      if(i != 0) {
         int ant = DSU::f(i - 1);
         heap.erase(heap.find(get(ant)));
      }
      if(urm != sz(p) - 1) 
         heap.erase(heap.find(get(urm)));
      
      //cerr << v[p[i]] << ' ' << v[p[urm]] << '\n';
      
      if(v[p[i]] < v[p[urm]]) {
         DSU::unite(i, urm);
         if(i != 0) {
            int ant = DSU::f(i - 1);
            heap.insert(get(ant));
         }
         if(DSU::nxt[i] != sz(p) - 1)
            heap.insert(get(i));
      }
      else {
         if(i != 0) {
            int ant = DSU::f(i - 1);
            DSU::unite(ant, i);
            heap.insert(get(ant));
         }
         if(urm != sz(p) - 1)
            heap.insert(get(urm));
      }  
   }
   
   return sz(heap) + 1;
}
#undef int

• Subtask 1: 0 / 4
• Subtask 2: 0 / 11
• Subtask 3: 0 / 12
• Subtask 4: 0 / 14
• Subtask 5: 0 / 17
• Subtask 6: 0 / 19
• Subtask 7: 0 / 23