Submission #718450

#	Time	Username	Problem	Language	Result	Execution time	Memory
718450		baojiaopisu	Counting Mushrooms (IOI20_mushrooms)	C++14	86.59 / 100	11 ms	512 KiB

mushrooms

#include "mushrooms.h"
#include <vector>
#include <iostream> 
#include <algorithm>    
#include <array>        
#include <random>      
#include <chrono>       

using namespace std;
#define pb push_back
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

int count_mushrooms(int n) {
	vector<int> a, b;
	vector<int> not_solved;
	for(int i = 1; i < n; i++) not_solved.pb(i);

	a.pb(0);
	shuffle(not_solved.begin(), not_solved.end(), rng);
	int res = 1;

	while(not_solved.size()) {
		if(a.size() >= b.size()) {
			if(a.size() >= 150) {
				vector<int> r;
				while(not_solved.size() && r.size() < a.size()) {
					r.pb(not_solved.back());
					not_solved.pop_back();
				}

				vector<int> ask;
				for(int i = 0; i < (int)a.size(); i++) {
					if(i < r.size()) ask.pb(r[i]);
					ask.pb(a[i]);
				}

				int x = use_machine(ask);
				res += r.size() - ((x + 1) / 2);
				if(x & 1) {
					b.pb(r[0]);
					swap(r[0], r[r.size() - 1]);
					r.pop_back();
				} else {
					a.pb(r[0]);
					swap(r[0], r[r.size() - 1]);
					r.pop_back();
				}
			} else {
				if(a.size() == 1 || not_solved.size() == 1) {
					int u = not_solved.back();
					not_solved.pop_back();
					if(use_machine({a[0], u})) {
						b.pb(u);
					} else {
						++res;
						a.pb(u);
					}
				} else {
					int u = not_solved.back();
					not_solved.pop_back();
					int v = not_solved.back();
					not_solved.pop_back();
					int d = use_machine({a[0], u, a[1], v});
					if(d & 1) b.pb(v); else a.pb(v), res++;
					if(d & 2) b.pb(u); else a.pb(u), res++;
				}
			}
		} else {
			if(b.size() >= 150) {
				vector<int> r;
				while(not_solved.size() && r.size() < b.size()) {
					r.pb(not_solved.back());
					not_solved.pop_back();
				}

				vector<int> ask;
				for(int i = 0; i < (int)b.size(); i++) {
					if(i < r.size()) ask.pb(r[i]);
					ask.pb(b[i]);
				}

				int x = use_machine(ask);
				if(x & 1) {
					a.pb(r[0]);
					swap(r[0], r[r.size() - 1]);
					r.pop_back();
				} else {
					b.pb(r[0]);
					swap(r[0], r[r.size() - 1]);
					r.pop_back();
				}
				res += (x + 1) / 2;
			} else {
				if(b.size() == 1 || not_solved.size() == 1) {
					int u = not_solved.back();
					not_solved.pop_back();
					if(use_machine({b[0], u})) {
						a.pb(u);
						++res;
					} else b.pb(u);
				} else {
					int u = not_solved.back();
					not_solved.pop_back();
					int v = not_solved.back();
					not_solved.pop_back();
					int d = use_machine({b[0], u, b[1], v});
					if(d & 1) a.pb(v), res++; else b.pb(v);
					if(d & 2) a.pb(u), res++; else b.pb(u);
				}
			}
		}
	}

	return res;
}

Compilation message (stderr)

mushrooms.cpp: In function 'int count_mushrooms(int)':
mushrooms.cpp:33:11: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   33 |      if(i < r.size()) ask.pb(r[i]);
      |         ~~^~~~~~~~~~
mushrooms.cpp:78:11: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   78 |      if(i < r.size()) ask.pb(r[i]);
      |         ~~^~~~~~~~~~

• Subtask 1: 86.59 / 100