Submission #1018649

#	Time	Username	Problem	Language	Result	Execution time	Memory
1018649		huutuan	도시들 (IOI15_towns)	C++14	35 / 100	10 ms	860 KiB

towns

#include "towns.h"

#include <bits/stdc++.h>

using namespace std;

int dd[200][200], d1[200], d2[200];

mt19937 rng(69420);

int GetDistance(int u, int v){
   if (u==v) return 0;
   if (dd[u][v]) return dd[u][v];
   int tmp=getDistance(u, v);
   dd[u][v]=tmp; dd[v][u]=tmp;
   return tmp;
}

int hubDistance(int N, int sub) {
   memset(dd, 0, sizeof dd);
   memset(d1, 0, sizeof d1);
   memset(d2, 0, sizeof d2);
   int u=0, dis=0;
   for (int i=1; i<N; ++i){
      int d=GetDistance(0, i);
      if (d>dis){
         dis=d;
         u=i;
      }
   }
   dis=0;
   int v=u;
   for (int i=0; i<N; ++i) if (i!=u){
      int d=GetDistance(u, i);
      d1[i]=d;
      if (d>dis){
         dis=d;
         v=i;
      }
   }
   int ans=1e9;
   vector<pair<int, int>> vv;
   for (int i=0; i<N; ++i) if (i!=u && i!=v){
      d2[i]=GetDistance(v, i);
      int common=(d1[i]+d2[i]-dis)/2;
      int dl=d1[i]-common, dr=d2[i]-common;
      ans=min(ans, max(dl, dr));
      vv.emplace_back(dl, dr);
   }
   if (sub<=2) return ans;
   d1[u]=d2[v]=0;
   d1[v]=d2[u]=dis;
   sort(vv.begin(), vv.end());
   vv.resize(unique(vv.begin(), vv.end())-vv.begin());
   int cnt=0;
   for (auto &ii:vv) if (max(ii.first, ii.second)==ans) ++cnt;
   int mx=N/2;
   for (auto &ii:vv) if (max(ii.first, ii.second)==ans){
      int szl=0, szr=0;
      vector<int> child;
      for (int i=0; i<N; ++i){
         int common=(d1[i]+d2[i]-dis)/2;
         int dl=d1[i]-common, dr=d2[i]-common;
         if (dl<ii.first) ++szl;
         else if (dl>ii.first) ++szr;
         else child.push_back(i);
      }
      if (szl>mx || szr>mx) continue;
      vector<pair<int, int>> subtree;
      if (sub==4){
         if (child.size()) subtree.emplace_back(child[0], child.size());
      }else{
         shuffle(child.begin(), child.end(), rng);
         int sum=szl+szr;
         while (child.size()){
            vector<int> nc;
            subtree.emplace_back(child[0], 0);
            for (int i:child){
               bool check=0;
               int ff=GetDistance(i, subtree.back().first);
               int common=(d1[i]+d1[subtree.back().first]-ff-ii.first*2)/2;
               if (common){
                  ++subtree.back().second;
                  check=1;
                  ++sum;
               }else nc.push_back(i);
               if (subtree.back().second>N/2) break;
               if (sum>=N-N/2) break;
            }
            if (subtree.back().second>N/2) break;
            if (sum>=N-N/2) break;
            child.swap(nc);
         }
      }
      bool check=szl<=mx && szr<=mx;
      for (auto &i:subtree) check&=i.second<=mx;
      if (check) return ans;
   }
   return -ans;
}

Compilation message (stderr)

towns.cpp: In function 'int hubDistance(int, int)':
towns.cpp:63:31: warning: unused variable 'dr' [-Wunused-variable]
   63 |          int dl=d1[i]-common, dr=d2[i]-common;
      |                               ^~
towns.cpp:79:21: warning: variable 'check' set but not used [-Wunused-but-set-variable]
   79 |                bool check=0;
      |                     ^~~~~

• Subtask 1: 13 / 13
• Subtask 2: 12 / 12
• Subtask 3: 0 / 13
• Subtask 4: 10 / 10
• Subtask 5: 0 / 13
• Subtask 6: 0 / 39