Submission #872706

#	Time	Username	Problem	Language	Result	Execution time	Memory
872706		LucaLucaM	Detecting Molecules (IOI16_molecules)	C++17	100 / 100	126 ms	27620 KiB

molecules

#include "molecules.h"
#ifdef LOCAL
#include "grader.cpp"
#endif
#include <vector>
#include <cassert>
#include <algorithm>
#include <set>
#include <map>

typedef long long ll;

std::vector<int> find_subset(int l, int u, std::vector<int> w) {
  int n = (int) w.size();
  std::vector<std::pair<int, int>> a(n);
  for (int i = 0; i < n; i++) {
    a[i] = {w[i], i};
  }
  std::sort(a.begin(), a.end());

  /**
  l <= sum[i] - sum[j - 1] <= u   | -sum[i]
  =>
  l - sum[i] <= -sum[j - 1] <= u - sum[i]  | *-1
  sum[i] - l >= sum[j - 1] >= sum[i] - u
  **/

  std::set<ll> st;
  std::map<ll, int> pos;
  ll s = 0;
  st.insert(0);
  pos[0] = -1;
  for (int i = 0; i < n; i++) {
    auto [value, idx] = a[i];
    s += value;
    auto it = *st.lower_bound(s - u);
    if (it <= s - l) {
      std::vector<int> ret;
      for (int j = pos[it] + 1; j <= i; j++) {
        ret.push_back(a[j].second);
      }
      return ret;
    }
    st.insert(s);
    pos[s] = i;
  }
  return {};
}

/**

4 15 17
6 8 8 7


**/

• Subtask 1: 9 / 9
• Subtask 2: 10 / 10
• Subtask 3: 12 / 12
• Subtask 4: 15 / 15
• Subtask 5: 23 / 23
• Subtask 6: 31 / 31