Submission #392623

#	Time	Username	Problem	Language	Result	Execution time	Memory
392623		usachevd0	Roller Coaster Railroad (IOI16_railroad)	C++14	100 / 100	226 ms	17784 KiB

railroad

#include <bits/stdc++.h>
#ifndef DEBUG
  #include "railroad.h"
#endif

using namespace std;

#define fi first
#define se second
#define mp make_pair
#define pb push_back
#define all(a) (a).begin(), (a).end()
using ll = long long;
using ull = unsigned long long;
using pii = pair<int, int>;
using pil = pair<int, ll>;
using pli = pair<ll, int>;
using pll = pair<ll, ll>;
using ld = long double;
template<typename T1, typename T2> bool chkmin(T1& x, T2 y) {
  return y < x ? (x = y, true) : false;
}
template<typename T1, typename T2> bool chkmax(T1& x, T2 y) {
  return y > x ? (x = y, true) : false;
}
void debug_out() {
  cerr << endl;
}
template<typename T1, typename... T2> void debug_out(T1 A, T2... B) {
  cerr << ' ' << A;
  debug_out(B...);
}
template<typename T> void mdebug_out(T* a, int n) {
  for (int i = 0; i < n; ++i) {
    cerr << a[i] << ' ';
  }
  cerr << endl;
}
#ifdef DEBUG
  #define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
  #define mdebug(a, n) cerr << #a << ": ", mdebug_out(a, n)
#else
  #define debug(...) 1337
  #define mdebug(a, n) 1337
#endif
template<typename T> ostream& operator << (ostream& stream, const vector<T>& v) {
  for (auto& x : v) {
    stream << x << ' ';
  }
  return stream;
}
template<typename T1, typename T2> ostream& operator << (ostream& stream, const pair<T1, T2>& p) {
  return stream << p.first << ' ' << p.second;
}

const int inf = 1e9 + 1337;

namespace dsu {
  vector<int> q;
  
  void init(int n) {
    q.assign(n, -1);
  }

  int gt(int x) {
    return q[x] < 0 ? x : q[x] = gt(q[x]);
  }

  bool join(int x, int y) {
    x = gt(x);
    y = gt(y);
    if (x == y) return false;
    if (-q[x] < -q[y]) swap(x, y);
    q[x] += q[y];
    q[y] = x;
    return true;
  }
}

ll plan_roller_coaster(vector<int> s, vector<int> t) {
  s.push_back(inf);
  t.push_back(1);
  int n = s.size();
  vector<int> points;
  for (int i = 0; i < n; ++i) {
    points.push_back(s[i]);
    points.push_back(t[i]);
  }
  sort(all(points));
  points.resize(unique(all(points)) - points.begin());
  int m = points.size();
  auto compr = [&](int x) -> int {
    return lower_bound(all(points), x) - points.begin();
  };
  dsu::init(m);
  vector<int> cs(n), ct(n), bal(m + 1, 0);
  for (int i = 0; i < n; ++i) {
    cs[i] = compr(s[i]);
    ct[i] = compr(t[i]);
    dsu::join(cs[i], ct[i]);
    ++bal[cs[i]];
    --bal[ct[i]];
  }
  ll ans = 0;
  for (int j = 0; j < m; ++j) {
    bal[j + 1] += bal[j];
    if (bal[j] != 0) {
      dsu::join(j, j + 1);
      if (bal[j] > 0) {
        ans += bal[j] * (ll)(points[j + 1] - points[j]);
      }
    }
  }
  vector<pli> edges;
  for (int j = 0; j + 1 < m; ++j) {
    if (dsu::gt(j) != dsu::gt(j + 1)) {
      edges.emplace_back(points[j + 1] - points[j], j);
    }
  }
  sort(all(edges));
  for (auto& e : edges) {
    ll w = e.fi;
    int j = e.se;
    if (dsu::join(j, j + 1)) {
      ans += w;
    }
  }
  return ans;
}

#ifdef DEBUG
int32_t main() {
#ifdef DEBUG
  freopen("in", "r", stdin);
#endif
  ios::sync_with_stdio(0);
  cin.tie(0);

  int n;
  cin >> n;
  vector<int> s(n), t(n);
  for (int i = 0; i < n; ++i) {
    cin >> s[i] >> t[i];
  }
  cout << plan_roller_coaster(s, t) << '\n';

  return 0;
}
#endif

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