Submission #742661

#	Time	Username	Problem	Language	Result	Execution time	Memory
742661		doowey	Rarest Insects (IOI22_insects)	C++17	100 / 100	71 ms	560 KiB

insects

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

using namespace std;

typedef pair<int, int> pii;

#define fi first
#define se second
#define mp make_pair

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

int gen(int m){
    return ((int)rng() % m + m) % m;
}

int min_cardinality(int n) {
    int val;
    set<int> in;
    set<int> st;
    vector<int> cand;
    for(int i = 0 ; i < n; i ++ ){
        move_inside(i);
        val = press_button();
        cand.push_back(i);
        if(val > 1){
            move_outside(i);
        }
        else{
            in.insert(i);
        }
    }
    st = in;
    for(int i = 1; i < n; i ++ ){
        swap(cand[i], cand[gen(i + 1)]);
    }
    int dist = in.size();
    int l = 1;
    int r = n/dist + 1;
    int mid;
    while(l + 1 < r){
        mid = (l + r) / 2;
        if(mid * dist > n){
            r = mid;
            continue;
        }
        for(auto i : cand){
            if(!in.count(i)){
                move_inside(i);
                val = press_button();
                if(val > mid){
                    move_outside(i);
                }
                else{
                    in.insert(i);
                }
                if(in.size() == mid * dist) break;
            }
        }
        if(in.size() == mid * dist){
            l = mid;
            st = in;
        }
        else{
            r = mid;
            cand.clear();
            for(auto q : in){
                if(st.count(q)) continue;

                move_outside(q);
                cand.push_back(q);
            }
            for(int i = 1; i < cand.size(); i ++ ){
                swap(cand[i], cand[gen(i + 1)]);
            }
            in = st;
        }
    }
    return l;
}

Compilation message (stderr)

insects.cpp: In function 'int min_cardinality(int)':
insects.cpp:58:30: warning: comparison of integer expressions of different signedness: 'std::set<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   58 |                 if(in.size() == mid * dist) break;
      |                    ~~~~~~~~~~^~~~~~~~~~~~~
insects.cpp:61:22: warning: comparison of integer expressions of different signedness: 'std::set<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   61 |         if(in.size() == mid * dist){
      |            ~~~~~~~~~~^~~~~~~~~~~~~
insects.cpp:74:30: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   74 |             for(int i = 1; i < cand.size(); i ++ ){
      |                            ~~^~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 15 / 15
• Subtask 3: 75 / 75