Submission #1079730

#	Time	Username	Problem	Language	Result	Execution time	Memory
1079730		ArthuroWich	Counting Mushrooms (IOI20_mushrooms)	C++17	92.62 / 100	6 ms	600 KiB

mushrooms

#include "mushrooms.h"
#include<bits/stdc++.h>
using namespace std;
int count_mushrooms(int n) {
	int ans = 0, m = min(75, n);
	if (n <= 400) {
		for (int i = 1; i+1 < n; i += 2) {
			ans += use_machine({i, 0, i+1});
		}
		if (n % 2 == 0) {
			ans += use_machine({0, n-1});
		}
		return n-ans;
	}
	int as = 0, bs = 0;
	vector<int> a, b, st;
	a.push_back(0);
	if (use_machine({0, 1})) {
		b.push_back(1);
	} else {
		a.push_back(1);
	}
	if (use_machine({0, 2})) {
		b.push_back(2);
	} else {
		a.push_back(2);
	}
	if (b.size() == 2) {
		swap(a, b);
	}
	for (int i = n-1; i >= 3; i--) {
		st.push_back(i);
	}
	for (int i = 0; i < m; i++) {
		int f1 = st.back(), f2;
		st.pop_back();
		f2 = st.back();
		st.pop_back();
		int v = use_machine({f1, a[0], f2, a[1]});
		if (v == 0) {
			a.push_back(f1);
			a.push_back(f2);
		} else if (v == 1) {
			b.push_back(f1);
			a.push_back(f2);
		} else if (v == 2) {
			a.push_back(f1);
			b.push_back(f2);
		} else {
			b.push_back(f1);
			b.push_back(f2);
		}
	}
	if (b.size() > a.size()) {
		swap(a, b);
	}
	as = a.size();
	bs = b.size();
	while(!st.empty()) {
		int va = 0, vb = 0, vn = 0, v;
		vector<int> query;
		for (int i = 0; i < a.size() && !st.empty(); i++) {
			query.push_back(st.back());
			st.pop_back();
			query.push_back(a[i]);
			vn++;
		}
		v = use_machine(query);
		vb = (v+1)/2;
		va = vn-vb;
		as += va;
		bs += vb;
		if (v & 1) {
			b.push_back(query[0]);
		} else {
			a.push_back(query[0]);
		}
		if (b.size() > a.size()) {
			swap(as, bs);
			swap(a, b);
		}
	}
	if (count(b.begin(), b.end(), 0)) {
		swap(as, bs);
	}
	return as;
}

Compilation message (stderr)

mushrooms.cpp: In function 'int count_mushrooms(int)':
mushrooms.cpp:62:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   62 |   for (int i = 0; i < a.size() && !st.empty(); i++) {
      |                   ~~^~~~~~~~~~

• Subtask 1: 92.623 / 100