Submission #1020686

#	Time	Username	Problem	Language	Result	Execution time	Memory
1020686		huutuan	Aliens (IOI16_aliens)	C++14	25 / 100	2076 ms	176860 KiB

aliens

#include "aliens.h"

#include <bits/stdc++.h>

using namespace std;

#define int long long

const int inf=1e18;

struct Line{
   mutable int k, m, p;
   bool operator<(const Line &a) const { return k<a.k; }
   bool operator<(int x) const { return p<x; }
};

struct LineContainer: multiset<Line, less<>>{
   int div(int x, int y){
      return x/y-((x^y)<0 && (x%y));
   }
   bool isect(iterator x, iterator y){
      if (y==end()) return x->p=inf, 0;
      if (x->k==y->k) x->p=x->m>=y->m?inf:-inf;
      else x->p=div(y->m-x->m, x->k-y->k);
      return x->p>=y->p;
   }
   void add(int k, int m){
      k=-k, m=-m;
      auto z=insert({k, m, 0}), y=z++, x=y;
      while (isect(y, z)) z=erase(z);
      if (x!=begin() && isect(--x, y)) isect(x, erase(y));
      while ((y=x)!=begin() && (--x)->p>=y->p) isect(x, erase(y));
   }
   int query(int x){
      auto l=*lower_bound(x);
      return (-l.k)*x+(-l.m);
   }
};

long long take_photos(int32_t n, int32_t m, int32_t k, vector<int32_t> r, vector<int32_t> c) {
   vector<pair<int, int>> v;
   for (int i=0; i<n; ++i){
      v.emplace_back(min(r[i], c[i]), max(r[i], c[i]));
   }
   sort(v.begin(), v.end());
   vector<pair<int, int>> v2;
   for (int i=0; i<(int)v.size(); ++i){
      int j=i;
      while (j+1<(int)v.size() && v[j+1].first==v[i].first) ++j;
      if (v2.empty() || v2.back().second<v[j].second) v2.push_back(v[j]);
      i=j;
   }
   n=v2.size();
   for (auto &i:v2) ++i.second;
   vector<vector<int>> f(n+1, vector<int>(k+1, inf));
   vector<LineContainer> cht(k);
   f[0][0]=0;
   for (int i=1; i<=n; ++i){
      int x=-2*v2[i-1].first, y=v2[i-1].first*v2[i-1].first;
      if (i!=1 && v2[i-2].second>v2[i-1].first) y-=(v2[i-2].second-v2[i-1].first)*(v2[i-2].second-v2[i-1].first);
      for (int j=1; j<=k; ++j){
         if (f[i-1][j-1]!=inf) cht[j-1].add(x, y+f[i-1][j-1]);
         if (cht[j-1].size()) f[i][j]=min(f[i][j], v2[i-1].second*v2[i-1].second+cht[j-1].query(v2[i-1].second));
      }
   }
   return *min_element(f[n].begin(), f[n].end());
}

• Subtask 1: 4 / 4
• Subtask 2: 12 / 12
• Subtask 3: 9 / 9
• Subtask 4: 0 / 16
• Subtask 5: 0 / 19
• Subtask 6: 0 / 40