Submission #828729

#	Time	Username	Problem	Language	Result	Execution time	Memory
828729		Abrar_Al_Samit	Counting Mushrooms (IOI20_mushrooms)	C++17	90.40 / 100	7 ms	464 KiB

mushrooms

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

const int bl = 240;

int count_mushrooms(int n) {
	vector<int>mac;

	int c1 = use_machine(mac = {0, 1});
	if(n==2) return 1 + 1-c1;

	int c2 = use_machine(mac = {0, 2});

	int tp[n];
	tp[0] = 1;
	tp[1] = 1-c1;
	tp[2] = 1-c2;

	int s1, s2;
	if(c1 && c2) s1 = 1, s2 = 2;
	else {
		s1 = 0;
		if(c1) s2 = 2;
		else s2 = 1;
	}

	if(n==3) {
		return tp[0] + tp[1] + tp[2];
	}

	int cnt[2] = {0};

	int upto;
	for(int i=3; i<min(bl, n); i+=2) {
		if(i==n-1) {
			tp[i] = 1 - use_machine(mac = {0, i});
			upto = i;
		} else {
			int c = use_machine(mac = {i, s1, i+1, s2});
			if(c==0) {
				tp[i] = tp[i+1] = tp[s1];
			} else if(c==1) {
				tp[i] = 1-tp[s1];
				tp[i+1] = tp[s1];
			} else if(c==2) {
				tp[i+1] = 1-tp[s1];
				tp[i] = tp[s1];
			} else {
				tp[i] = tp[i+1] = 1-tp[s1];
			}

			++cnt[tp[i]], ++cnt[tp[i+1]];

			upto = i+1;
			if(max(cnt[tp[i]], cnt[tp[i+1]])>=bl/2) {
				break;
			}
		}
	}

	int ans = 0;
	vector<int>cl[2];
	for(int i=0; i<=upto; ++i) {
		cl[tp[i]].push_back(i);

		ans += tp[i];
	}

	if(upto == n-1) return ans;

	int cr = upto + 1;

	while(cr < n) {
		mac.clear();

		bool mxw = 0;
		if(cl[1].size()>=cl[0].size()) mxw = 1;

		mac = {cr}; int f = cr; ++cr;

		int ctr = 0;
		for(int j=0; j<cl[mxw].size(); ++j) {
			mac.push_back(cl[mxw][j]);
			if(cr==n) {
				while(cl[mxw].size()!=j+1) cl[mxw].pop_back();
				break;
			}

			if(j!=cl[mxw].size()-1) mac.push_back(cr), ++cr, ++ctr;
		}

		int get = use_machine(mac);

		if(get & 1) {
			cl[1-mxw].push_back(f);
			--get;
			ans += 1-mxw;
		} else {
			cl[mxw].push_back(f);
			ans += mxw;
		}

		if(!mxw) ans += get / 2;
		else ans += (ctr * 2 - get) / 2;
	}
	return ans;
}

Compilation message (stderr)

mushrooms.cpp: In function 'int count_mushrooms(int)':
mushrooms.cpp:83:17: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   83 |   for(int j=0; j<cl[mxw].size(); ++j) {
      |                ~^~~~~~~~~~~~~~~
mushrooms.cpp:86:25: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   86 |     while(cl[mxw].size()!=j+1) cl[mxw].pop_back();
      |           ~~~~~~~~~~~~~~^~~~~
mushrooms.cpp:90:8: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   90 |    if(j!=cl[mxw].size()-1) mac.push_back(cr), ++cr, ++ctr;
      |       ~^~~~~~~~~~~~~~~~~~
mushrooms.cpp:70:2: warning: 'upto' may be used uninitialized in this function [-Wmaybe-uninitialized]
   70 |  if(upto == n-1) return ans;
      |  ^~

• Subtask 1: 90.4 / 100