Submission #683167

#	Time	Username	Problem	Language	Result	Execution time	Memory
683167		cadmiumsky	Roller Coaster Railroad (IOI16_railroad)	C++17	100 / 100	584 ms	56592 KiB

railroad

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

using ll = long long;

//#define int ll
#define sz(x) ((int)(x).size())

using pii = pair<int,int>;
using tii = tuple<int,int,int>;

const int nmax = 5e5 + 5, inf = 1e9 + 5; 

vector<tii> edg;

namespace DSU {
  int dsu[nmax];
  void init(int n) {
    for(int i = 0; i <= n; i++)
      dsu[i] = i;
  }
  int f(int x) { return x == dsu[x]? x: dsu[x] = f(dsu[x]); }
  int cost(int a, int b, int w) {
    a = f(a);
    b = f(b);
    if(a == b) return 0;
    dsu[a] = b;
    return w;
  }
}

long long plan_roller_coaster(vector<int> s, vector<int> t) {
  t.emplace_back(0);
  s.emplace_back(inf);
  
  unordered_map<int,int> nrm;
  map<int,int> smen;
  for(auto x : s)
    smen[x]++;
  for(auto x : t)
    smen[x]--;
  
  int edgc = 0;
  int last = 0, cnt = 0;
  
  ll cost = 0;
  
  for(auto [a, b] : smen)  {
    nrm[a] = cnt++;
    if(edgc == 0) {
      //cerr << edgc << ' ' << a << ' ' << last << ' ' << cost << '+' << (a - last) * max(edgc, 0) << '\n';
      edg.emplace_back(nrm[last], nrm[a], a - last);
    }
    else {
      //cerr << edgc << ' ' << a << ' ' << last << ' ' << cost << '+' << (a - last) * max(edgc, 0) << '\t';
      cost += (ll)(a - last) * max(edgc, 0);
      //cerr << cost << '\n';
      edg.emplace_back(nrm[last], nrm[a], 0);                                                                                                                                                
    }
    edgc += b;
    last = a;
  }
  for(int i = 0; i < sz(s); i++)
    edg.emplace_back(nrm[s[i]], nrm[t[i]], 0);
  DSU::init(sz(nrm));
  sort(all(edg), [](auto a, auto b) { return get<2>(a) < get<2>(b); });
  for(auto [x, y, w] : edg) {
    //cerr << x <<  ' ' << y << ' ' << w << '\n';
    cost += DSU::cost(x, y, w);
  }
  return cost;
}

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