Submission #936725

#	Time	Username	Problem	Language	Result	Execution time	Memory
936725		GrindMachine	Rarest Insects (IOI22_insects)	C++17	99.83 / 100	33 ms	1180 KiB

insects

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
 
using namespace std;
using namespace __gnu_pbds;
 
template<typename T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
typedef long long int ll;
typedef long double ld;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
 
#define fastio ios_base::sync_with_stdio(false); cin.tie(NULL)
#define pb push_back
#define endl '\n'
#define sz(a) (int)a.size()
#define setbits(x) __builtin_popcountll(x)
#define ff first
#define ss second
#define conts continue
#define ceil2(x,y) ((x+y-1)/(y))
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define yes cout << "Yes" << endl
#define no cout << "No" << endl
 
#define rep(i,n) for(int i = 0; i < n; ++i)
#define rep1(i,n) for(int i = 1; i <= n; ++i)
#define rev(i,s,e) for(int i = s; i >= e; --i)
#define trav(i,a) for(auto &i : a)
 
template<typename T>
void amin(T &a, T b) {
    a = min(a,b);
}
 
template<typename T>
void amax(T &a, T b) {
    a = max(a,b);
}
 
#ifdef LOCAL
#include "debug.h"
#else
#define debug(x) 42
#endif
 
/*
 
refs:
https://youtu.be/mm5Nv81P5u8?t=19948
edi
 
*/
 
const int MOD = 1e9 + 7;
const int N = 1e5 + 5;
const int inf1 = int(1e9) + 5;
const ll inf2 = ll(1e18) + 5;
 
#include "insects.h"

int min_cardinality(int n) {
    vector<int> uniq_guys;

    rep(i,n){
        move_inside(i);
        int res = press_button();
        if(res >= 2){
            move_outside(i);
        }
        else{
            uniq_guys.pb(i);
        }
    }

    trav(i,uniq_guys){
        move_outside(i);
    }
    
    if(sz(uniq_guys) == 1){
        return n;
    }

    if(sz(uniq_guys) == n){
        return 1;
    }

    vector<bool> ignore(n);
    vector<int> in_machine;

    auto ok = [&](int mid){
        // check if ans <= mid
        // check if ans < mid+1

        vector<int> good, bad;
 
        rev(i,n-1,0){
            if(ignore[i]) conts;
            if(sz(in_machine)+sz(good) == sz(uniq_guys)*(mid+1)){
                break;
            }
            move_inside(i);
            int res = press_button();
            if(res > mid+1){
                bad.pb(i);
                move_outside(i);
            }
            else{
                good.pb(i);
            }
        }

        if(sz(in_machine)+sz(good) == sz(uniq_guys)*(mid+1)){
            // everybody occurs at least mid+1 times
            // anybody in the machine would stay in the machine forever
            trav(i,good){
                in_machine.pb(i);
                ignore[i] = 1;
            }

            return false;
        }
        else{
            // at least one guy occurs < (mid+1) #of times
            // i.e at least one guys occurs <= mid #of times
            // right endpoint of range decreases
            // so ignore all bad guys in future iterations
            // remove all good guys in this iteration from the machine
            trav(i,bad){
                ignore[i] = 1;
            }
            trav(i,good){
                move_outside(i);
            }

            return true;
        }
    };

    int l = 1, r = n/sz(uniq_guys)-1;
    int ans = n/sz(uniq_guys);
 
    while(l <= r){
        int mid = (l+r) >> 1;
        // is min <= mid?
        if(ok(mid)){
            ans = mid;
            r = mid-1;
        }
        else{
            l = mid+1;
        }
    }
 
    return ans;
}

• Subtask 1: 10 / 10
• Subtask 2: 15 / 15
• Subtask 3: 74.83 / 75