Submission #434512

#	Time	Username	Problem	Language	Result	Execution time	Memory
434512		rqi	Counting Mushrooms (IOI20_mushrooms)	C++14	79.02 / 100	12 ms	524 KiB

mushrooms

#include "mushrooms.h"
#include <bits/stdc++.h>
using namespace std;

typedef vector<int> vi;

#define pb push_back
#define bk back()

#define all(x) begin(x), end(x)
#define sz(x) (int)(x).size()

mt19937 rng(127);

int count_mushrooms(int n) {
	vi known[2];
	vi untested;

	int ans = 1;
	known[0].pb(0);
	for(int i = 1; i < n; i++){
		untested.pb(i);
	}
	shuffle(all(untested), rng);

	while(sz(untested)){
		int better_ind = 0;
		if(sz(known[1]) > sz(known[0])) better_ind = 1;

		vi to_test;
		int special = untested.bk; untested.pop_back();
		to_test.pb(special);
		to_test.pb(known[better_ind][0]);

		vi tested;
		for(int i = 1; i < min(sz(untested), sz(known[better_ind])); i++){
			tested.pb(untested.bk);
			to_test.pb(untested.bk); untested.pop_back();
			to_test.pb(known[better_ind][i]);
		}

		int res = use_machine(to_test);

		int special_identity = better_ind;
		if(res % 2 == 0){

		}
		else{
			special_identity^=1;
			
		}
		known[special_identity].pb(special);

		if(special_identity == 0){
			ans++;
		}


		// cout << res/2 << " " << sz(tested) << "\n";
		if(res/2 == sz(tested)){
			for(auto u: tested){
				known[better_ind^1].pb(u);
			}
		}
		else if(res/2 == 0){
			for(auto u: tested){
				known[better_ind].pb(u);
			}
		}

		if(better_ind == 0){
			ans+=sz(tested)-res/2;
		}
		else{
			ans+=res/2;
		}


	}

	return ans;
}

• Subtask 1: 79.021 / 100