Submission #305927

#	Time	Username	Problem	Language	Result	Execution time	Memory
305927		myungwoo	Counting Mushrooms (IOI20_mushrooms)	C++17	92.24 / 100	11 ms	384 KiB

mushrooms

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

int count_mushrooms(int N)
{
	int iter = 71;
	vector<int> arr[2] = {{0}, {}};
	int pt = 1;
	// Step 1: Check type of mushroom one by one
	while (pt < N){
		arr[use_machine({0, pt})].push_back(pt);
		pt++;
		if (arr[0].size() >= 2 || arr[1].size() >= 2) break;
	}
	// Step 2: Check type of mushroom two by one
	while (pt < N){
		int t = arr[1].size() >= 2;
		vector<int> test = {arr[t][0], pt, arr[t][1]};
		if (pt+1 < N) test.push_back(pt+1);
		int res = use_machine(test);
		arr[res>>1&1^t].push_back(pt);
		if (pt+1 < N) arr[res&1^t].push_back(pt+1);
		pt += 2;
		if (!--iter) break;
	}
	// Step 3: Count number of type 0 mushrooms s by one
	int zero_count = arr[0].size();
	while (pt < N){
		int t = arr[1].size() > arr[0].size();
		vector<int> test;
		for (int i=0;pt+i<N&&i<arr[t].size();i++){
			test.push_back(arr[t][i]);
			test.push_back(pt+i);
		}
		int res = use_machine(test);
		arr[res&1^t].push_back(test.back());
		int cnt = res+1>>1;
		if (!t) cnt = test.size()/2-cnt;
		zero_count += cnt;
		pt += test.size()/2;
	}
	return zero_count;
}

Compilation message (stderr)

mushrooms.cpp: In function 'int count_mushrooms(int)':
mushrooms.cpp:22:13: warning: suggest parentheses around arithmetic in operand of '^' [-Wparentheses]
   22 |   arr[res>>1&1^t].push_back(pt);
      |       ~~~~~~^~
mushrooms.cpp:23:24: warning: suggest parentheses around arithmetic in operand of '^' [-Wparentheses]
   23 |   if (pt+1 < N) arr[res&1^t].push_back(pt+1);
      |                     ~~~^~
mushrooms.cpp:32:25: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   32 |   for (int i=0;pt+i<N&&i<arr[t].size();i++){
      |                        ~^~~~~~~~~~~~~~
mushrooms.cpp:37:10: warning: suggest parentheses around arithmetic in operand of '^' [-Wparentheses]
   37 |   arr[res&1^t].push_back(test.back());
      |       ~~~^~
mushrooms.cpp:38:16: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   38 |   int cnt = res+1>>1;
      |             ~~~^~

• Subtask 1: 92.2449 / 100