# | Time | Username | Problem | Language | Result | Execution time | Memory |
---|---|---|---|---|---|---|---|
634177 | spacewalker | Rarest Insects (IOI22_insects) | C++17 | 0 ms | 0 KiB |
This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include "insects.h"
#include <bits/stdc++.h>
using namespace std;
int ceil(int n, int r) {
return n/r + n%r;
}
// Get an array of insects, such that all their types are distinct
// The representatives are left inside the machine
vector<int> getRepresentatives(int N) {
vector<int> inMachine;
for (int i = 0; i < N; ++i) {
move_inside(i);
if (press_button() > 1) {
move_outside(i);
} else {
inMachine.push_back(i);
}
}
return inMachine;
}
// find the max k such that all types have at least >= k insects
// in a query, we can check if all types have at least >= k' insects
int getAllLowerBound(vector<int> ids, int B, int answerMax, int machineBase) {
if (answerMax == 0) return 0; // base case
/*
printf("GALB([");
for (int v : ids) printf("%d ", v);
printf("], %d, %d)\n",B, answerMax);
*/
int mid = answerMax - 4 * answerMax / 5; // this is a guess
// printf("checking if min >= %d\n", mid);
set<int> inMachine;
for (int v : ids) {
move_inside(v);
if (press_button() > machineBase + mid) {
// this is the >midth insect of its type, keep it out
move_outside(v);
} else {
inMachine.insert(v);
}
}
// printf("%lu in machine\n", inMachine.size());
if (inMachine.size() >= mid * B) {
// check success; do a GALB on the rest now
vector<int> remaining;
for (int v : ids) if (inMachine.count(v) == 0) remaining.push_back(v);
return mid + getAllLowerBound(remaining, B, answerMax - mid, machineBase + mid);
} else {
// check fail; do a GALB with a lower ansMax
// note that it suffices to only use the ones in the machine
for (int v : inMachine) move_outside(v);
return getAllLowerBound(inMachine, B, mid - 1, machineBase);
}
}
int min_cardinality(int N) {
vector<int> reps = getRepresentatives(N);
int B = reps.size(); // B is the number of types
// printf("! %d unique types\n", B);
vector<int> insects;
set<int> inReps(begin(reps), end(reps));
for (int i = 0; i < N; ++i) {
if (inReps.count(i) == 0) insects.push_back(i);
}
return getAllLowerBound(insects, B, ceil(N - 1, B), 1) + 1;
}