Submission #1081608

#	Time	Username	Problem	Language	Result	Execution time	Memory
1081608		GrindMachine	Counting Mushrooms (IOI20_mushrooms)	C++17	77.40 / 100	5 ms	720 KiB

mushrooms

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

typedef long long int ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;

#define pb push_back
#define endl '\n'
#define conts continue
#define ff first
#define ss second
#define all(a) a.begin(),a.end()
#define rall(a) a.rbegin(),a.rend()
#define sz(a) (int)a.size()

#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 &x, T y){
	x = min(x,y);
}

template<typename T>
void amax(T &x, T y){
	x = max(x,y);
}

template<typename A,typename B>
string to_string(pair<A,B> p);

string to_string(const string &s){
	return "'"+s+"'";
}

string to_string(const char* s){
	return to_string((string)s);
}

string to_string(bool b){
	return b?"true":"false";
}

template<typename A>
string to_string(A v){
	string res = "{";
	trav(x,v){
		res += to_string(x)+",";
	}
	if(res.back() == ',') res.pop_back();
	res += "}";
	return res;
}

template<typename A,typename B>
string to_string(pair<A,B> p){
	return "("+to_string(p.ff)+","+to_string(p.ss)+")";
}

#define debug(x) cout << "[" << #x << "]: "; cout << to_string(x) << endl

const int MOD = 1e9 + 7;
const int N = 1e5 + 5;
const int inf1 = 1e9 + 5;
const ll inf2 = (ll)1e18 + 5;

#include "mushrooms.h"

int count_mushrooms(int n) {
	int B = min(n,80);

	vector<int> a(B);
	rep1(i,B-1){
		vector<int> v = {i-1,i};
		a[i] = a[i-1]^use_machine(v);
	}

	vector<int> v0,v1;
	rep(i,B){
		if(!a[i]){
			v0.pb(i);
		}
		else{
			v1.pb(i);
		}
	}

	int ptr = B-1;
	int ans = count(all(a),0);

	while(ptr < n-1){
		int siz = max(sz(v0),sz(v1));

		if(sz(v0) > sz(v1)){
			vector<int> v;
			for(int i = ptr+1; i < n; ++i){
				if(sz(v) >= siz) break;
				ptr = i;
				v.pb(i);
			}

			vector<int> ask;
			rep(i,sz(v)){
				ask.pb(v0[i]);
				ask.pb(v[i]);
			}

			int res = use_machine(ask);
			int sum = (sz(v)-1)*2+1;
			res = sum-res;

			if(res&1){
				ans++;
				v0.pb(v.back());
			}
			else{
				v1.pb(v.back());
			}

			ans += res/2;
		}
		else{
			vector<int> v;
			for(int i = ptr+1; i < n; ++i){
				if(sz(v) >= siz) break;
				ptr = i;
				v.pb(i);
			}

			vector<int> ask;
			rep(i,sz(v)){
				ask.pb(v1[i]);
				ask.pb(v[i]);
			}

			int res = use_machine(ask);

			if(res&1){
				ans++;
				v0.pb(v.back());
			}
			else{
				v1.pb(v.back());
			}

			ans += res/2;
		}
	}


	return ans;

	// for (int i = 0; i < n; i++)
	// 	m.push_back(i);
	// int c1 = use_machine(m);
	// m = {0, 1};
	// int c2 = use_machine(m);
	// return c1+c2;
}

• Subtask 1: 77.3973 / 100