Submission #898474

#	Time	Username	Problem	Language	Result	Execution time	Memory
898474		Essa2006	Counting Mushrooms (IOI20_mushrooms)	C++14	81.88 / 100	6 ms	820 KiB

mushrooms

#include<bits/stdc++.h>
using namespace std;
#define ll long long 
#define endl '\n'
#define FF first
#define SS second
#define all(a) a.begin(), a.end()
#define mod (ll)(1000000007)
#include "mushrooms.h"
 
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
 
int count_mushrooms(int n) {
    
	vector<int> A(n);
    vector<int> Z = {0}, O;
    for (int i = 0; i < n; i++) {
        A[i] = i;
    }
    shuffle(A.begin() + 1, A.end(), rng);
    
    int ans = 1, vr = 10, last = 0;
    for (int i = 1; i <= 2; i++){
        last = i;
        int cur = use_machine({Z.front(), A[i]});
        
        if (cur) {
            O.push_back(A[i]);
        }
        else {
            Z.push_back(A[i]);
            ans++;
        }
        
        if (n == i + 1) {
            return ans;
        }
    }
    
    if (Z.size() > O.size()) {
        for (int i = 3; i - 2 <= vr && i + 1 < n; i += 2) {
            last = i + 1;
            int cur = use_machine({Z[0], A[i], Z[1], A[i + 1]});
            
            if (cur == 0) {
                Z.push_back(A[i]);
                Z.push_back(A[i + 1]);
                ans += 2;
            }
            else if (cur == 1) {
                Z.push_back(A[i]);
                O.push_back(A[i + 1]);
                ans++;
            }
            else if (cur == 2) {
                O.push_back(A[i]);
                Z.push_back(A[i + 1]);
                ans++;
            }
            else {
                O.push_back(A[i]);
                O.push_back(A[i + 1]);
            }
        }
    }
    else {
        for (int i = 3; i - 2 <= vr && i + 1 < n; i += 2) {
            last = i + 1;
            int cur = use_machine({O[0], A[i], O[1], A[i + 1]});
            
            if (cur == 0) {
                O.push_back(A[i]);
                O.push_back(A[i + 1]);
            }
            else if (cur == 1) {
                O.push_back(A[i]);
                Z.push_back(A[i + 1]);
                ans++;
            }
            else if (cur == 2) {
                Z.push_back(A[i]);
                O.push_back(A[i + 1]);
                ans++;
            }
            else {
                Z.push_back(A[i]);
                Z.push_back(A[i + 1]);
                ans += 2;
            }
        }
    }
    
    
 
    int i = last + 1;
    while (i < n) {
        int j = i;
        vector<int>Ask;
        if (Z.size() > O.size()) {
            while (j < n){
                if (Z.size() < j - i + 1) {
                    break;
                }
                Ask.push_back(A[j]);
                Ask.push_back(Z[j - i]);
                j++;
            }
            int diff = use_machine(Ask);
            int all = Ask.size() / 2;
            if (diff & 1) {
                int Bs = (diff + 1) / 2;
                ans += all - Bs;
                O.push_back(A[i]);
            }
            else {
                int Bs = diff / 2;
                ans += all - Bs;
                Z.push_back(A[i]);
            }
        }
        
        else {
            while (j < n){
                if (O.size() < j - i + 1) {
                    break;
                }
                Ask.push_back(A[j]);
                Ask.push_back(O[j - i]);
                j++;
            }
            int diff = use_machine(Ask);
            int all = Ask.size() / 2;
            if (diff & 1) {
                int As = (diff + 1) / 2;
                ans += As;
                Z.push_back(A[i]);
            }
            else {
                int As = diff / 2;
                ans += As;
                O.push_back(A[i]);
            }
        }
        
        i = j;
    }
    return ans;
}

Compilation message (stderr)

mushrooms.cpp: In function 'int count_mushrooms(int)':
mushrooms.cpp:101:30: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
  101 |                 if (Z.size() < j - i + 1) {
      |                     ~~~~~~~~~^~~~~~~~~~~
mushrooms.cpp:124:30: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
  124 |                 if (O.size() < j - i + 1) {
      |                     ~~~~~~~~~^~~~~~~~~~~
mushrooms.cpp:132:17: warning: unused variable 'all' [-Wunused-variable]
  132 |             int all = Ask.size() / 2;
      |                 ^~~

• Subtask 1: 81.8841 / 100