Submission #799668

#	Time	Username	Problem	Language	Result	Execution time	Memory
799668		kirakaminski968	Roller Coaster Railroad (IOI16_railroad)	C++17	100 / 100	179 ms	22764 KiB

railroad

#include "railroad.h"
#include <bits/stdc++.h>
#define ll long long
using namespace std;
struct dsu{
  int par[400005];
  void init(int N){
    for(int i = 0;i<=N;++i) par[i] = i;
  }
  int finden(int x){
    return par[x] = (par[x] == x ? x : finden(par[x]));
  }
  bool unite(int x, int y){
    x = finden(x); y = finden(y);
    if(x == y){
      return false;
    }
    par[y] = x;
    return true;
  }
}D;
struct edge{
  int start, ende, wert;
  bool operator<(const edge &e)const{
    return wert < e.wert;
  }
};
int cnt[400005];
ll plan_roller_coaster(vector<int> s, vector<int> t){
  vector<int> merged; int n = (int)s.size();
  for(int i = 0;i<n;++i) {merged.push_back(s[i]); merged.push_back(t[i]);}
  sort(merged.begin(),merged.end());
  merged.resize(unique(merged.begin(),merged.end())-merged.begin());
  D.init(merged.size());
  for(int i = 0;i<n;++i){
    s[i] = lower_bound(merged.begin(),merged.end(),s[i])-merged.begin();
    t[i] = lower_bound(merged.begin(),merged.end(),t[i])-merged.begin();
    cnt[s[i]]++; cnt[t[i]]--; D.unite(s[i],t[i]);
  }
  int cur = 1; ll ans = 0;
  vector<edge> kanten;
  for(int i = merged.size()-1;i>=0;--i){
    cur += cnt[i];
    if(cur < 0){
      ans += -1ll * cur * (merged[i]-merged[i-1]);
      cnt[i-1] += cur;
      D.unite(i-1,i);
      cur = 0;
    }
    if(cur > 0 && i) D.unite(i,i-1);
    else if(cur == 0) kanten.push_back({i-1,i,merged[i]-merged[i-1]});
  }
  sort(kanten.begin(),kanten.end());
  for(auto p : kanten){
    if(D.unite(p.start,p.ende)) ans += p.wert;
  }
  return ans;
}

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