Submission #332102

#	Time	Username	Problem	Language	Result	Execution time	Memory
332102		LifeHappen__	Roller Coaster Railroad (IOI16_railroad)	C++14	100 / 100	268 ms	24532 KiB

railroad

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

using namespace std;

#define ii pair<int, int>
#define fi first
#define se second
#define pb push_back

struct dsu {
  vector <int> par;
  void init(int n){
    par.assign(n, 0);
    for (int i = 0; i < n; ++i) par[i] = i;
  }
  int findset(int u) {
    if(par[u] == u) return u;
    return par[u] = findset(par[u]);
  }
  bool mergeset(int u, int v) {
    u = findset(u), v = findset(v);
    if(u == v) return false;
    par[v] = u; return true;
  }
} pa;

long long plan_roller_coaster(vector<int> s, vector<int> t) {
  int n = s.size();
  #define int long long
  vector<int> vals;
  for (auto &v : s) vals.pb(v);
  for (auto &v : t) vals.pb(v);
  sort(begin(vals), end(vals));
  vals.resize(unique(begin(vals), end(vals)) - begin(vals));
  vector<int> can(vals.size() + 5, 0);
  pa.init(vals.size() + 10);
  for (int i = 0; i < n; ++i) {
    s[i] = lower_bound(begin(vals), end(vals), s[i]) - begin(vals);
    t[i] = lower_bound(begin(vals), end(vals), t[i]) - begin(vals);
    can[s[i]]++;
    can[t[i]]--;
    pa.mergeset(s[i], t[i]);
  }
  int m = vals.size();
  int cur = 1;
  long long ans = 0;
  vector<tuple<long long, int, int>> ts;
  for (int i = m - 1; i > 0; --i) {
    cur += can[i];
    if(cur < 0) {
      ans += 1ll * (vals[i - 1] - vals[i]) * cur;
      pa.mergeset(i - 1, i);
    } else if(cur > 0) pa.mergeset(i - 1, i);
    else ts.emplace_back(vals[i] - vals[i - 1], i, i - 1);
  }
  sort(begin(ts), end(ts));
  for (auto &_ : ts) {
    int64_t w;
    int u, v;
    tie(w, u, v) = _;
    if(pa.mergeset(u, v)) {
      ans += w;
    }
  }
  return ans;
}

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