Submission #1029777

#	Time	Username	Problem	Language	Result	Execution time	Memory
1029777		huutuan	Roller Coaster Railroad (IOI16_railroad)	C++14	100 / 100	165 ms	34340 KiB

railroad

#include "railroad.h"

#include <bits/stdc++.h>

using namespace std;

#define int long long

struct DSU{
   vector<int> lab;
   void init(int n){
      lab.assign(n+1, -1);
   }
   int find_set(int u){
      return lab[u]<0?u:lab[u]=find_set(lab[u]);
   }
   bool union_sets(int u, int v){
      u=find_set(u); v=find_set(v);
      if (u!=v){
         if (lab[u]>lab[v]) swap(u, v);
         lab[u]+=lab[v];
         lab[v]=u;
         return 1;
      }
      return 0;
   }
} dsu;

const int N=4e5+10;
int d[N];

long long plan_roller_coaster(vector<int32_t> s, vector<int32_t> t) {
   vector<int> vals={-1};
   s.push_back(1e9); t.push_back(1);
   for (auto i:s) vals.push_back(i);
   for (auto i:t) vals.push_back(i);
   sort(vals.begin(), vals.end()); vals.resize(unique(vals.begin(), vals.end())-vals.begin());
   int m=(int)vals.size()-1;
   dsu.init(m);
   for (auto &i:s) i=lower_bound(vals.begin(), vals.end(), i)-vals.begin();
   for (auto &i:t) i=lower_bound(vals.begin(), vals.end(), i)-vals.begin();
   int n=s.size();
   for (int i=0; i<n; ++i){
      ++d[s[i]];
      --d[t[i]];
      dsu.union_sets(s[i], t[i]);
   }
   partial_sum(d, d+N, d);
   int ans=0;
   vector<pair<int, pair<int, int>>> v;
   for (int i=1; i<m; ++i){
      if (d[i]) dsu.union_sets(i, i+1);
      if (d[i]>0) ans+=(vals[i+1]-vals[i])*d[i];
      v.push_back({vals[i+1]-vals[i], {i, i+1}});
   }
   sort(v.begin(), v.end());
   for (auto &i:v) if (dsu.union_sets(i.second.first, i.second.second)) ans+=i.first;
   return ans;
}

• Subtask 1: 11 / 11
• Subtask 2: 23 / 23
• Subtask 3: 30 / 30
• Subtask 4: 36 / 36