Submission #1040067

#	Time	Username	Problem	Language	Result	Execution time	Memory
1040067		Dan4Life	Counting Mushrooms (IOI20_mushrooms)	C++17	100 / 100	5 ms	884 KiB

mushrooms

#include "mushrooms.h"
#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define sz(a) (int)a.size()
#define all(a) begin(a),end(a)
using ll = long long;
map<vector<int>,int> M;

int useM(vector<int> v){
	if(M.count(v)) return M[v];
	return M[v]=use_machine(v);
}

const int B = 100;
vector<int> V[2];

int count_mushrooms(int n) {
	int ans = 1, i=1, P;
	if(n<=200){
		for(int i = 1; i < n; i++) 
			ans+=!useM({0,i});
		return ans;
	}
	V[0].clear(), V[1].clear(); V[0].pb(0);
	V[useM({0,i})].pb(i), i++;
	V[useM({0,i})].pb(i), i++;
	P = sz(V[1])>sz(V[0]);
	int x = useM({V[P][0],i,V[P][1],i+1});
	V[x%2?!P:P].pb(i+1); V[x>=2?!P:P].pb(i); i+=2;

	while(i<n and sz(V[0])+sz(V[1])<2*B-1){
		vector<int> v; v.clear();
		P = sz(V[1])>sz(V[0]);
		v.pb(V[P][0]), v.pb(i+1);
		v.pb(V[P][1]), v.pb(i+2);
		v.pb(V[P][2]), v.pb(i);
		int x = useM(v), c1=P, c2=P, c3=P, c4=P, c5=P;
		if(x%2) c3^=1, x--; 
		if(x!=2){
			if(x==4) c1^=1, c2^=1;
			V[c1].pb(i+1); V[c2].pb(i+2); V[c3].pb(i); i+=3;
		}
		else{ 
			if(sz(V[!P])>=2){
				v.clear(); v.pb(V[!P][0]), v.pb(i+1), v.pb(V[!P][1]); v.pb(V[P][0]); 
				v.pb(i+2); v.pb(V[P][1]); v.pb(i+3); v.pb(V[P][2]); v.pb(i+4);
				x = useM(v)-1; c1 = !P;
				if(x%2) c5^=1, x--;
				if(x==2) c4^=1;
				else if(x==4) c1^=1, c2^=1;
				else if(x==6) c1^=1, c2^=1, c4^=1;
				V[c1].pb(i+1); V[c2].pb(i+2); V[c3].pb(i); V[c4].pb(i+3); V[c5].pb(i+4); i+=5;
			}
			else{ 
				if(useM({0,i+1})) c1=1,c2=0;
				else c1=0, c2=1;
				V[c1].pb(i+1); V[c2].pb(i+2); V[c3].pb(i); i+=3;
			}
		}
	}
	ans=sz(V[0]);
	while(i<n){
		P = sz(V[1])>sz(V[0]);
		vector<int> v; v.clear();
		for(int j = 0; j < sz(V[P]) and i<n; j++)
			v.pb(V[P][j]), v.pb(i), i++;
		int x = useM(v);
		if(!P) ans+=sz(v)/2;
		if(x%2) ans+=P?1:-1, V[P^1].pb(v.back());
		else V[P].pb(v.back());
		ans+=x/2*(P?1:-1);
		if(i==n) break;
	}
	return ans;
}

• Subtask 1: 100 / 100