Submission #897685

#	Time	Username	Problem	Language	Result	Execution time	Memory
897685		Essa2006	Counting Mushrooms (IOI20_mushrooms)	C++14	25 / 100	15 ms	808 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 = rng() % 100;
    int last;
    for (int i = 1; i <= 2 * vr; 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;
        }
    }
    
    

    int i = last + 1;
    while (i < n - 1) {
        int j = i;
        vector<int>Ask;
        if (Z.size() > O.size()) {
            while (j < n){
                Ask.push_back(A[j]);
                if (Z.size() < j - i + 1 || j == n - 1) {
                    j++;
                    break;
                }
                Ask.push_back(Z[j - i]);
                j++;
            }
            int diff = use_machine(Ask);
            int all = (Ask.size() + 1) / 2;
            if (diff & 1) {
                int Bs = (diff + 1) / 2;
                ans += all - Bs;
            }
            else {
                int diff2 = use_machine({Z.front(), A[i]});
                if (diff2) {
                    O.push_back(A[i]);
                    O.push_back(A[j - 1]);
                    ans += all - (diff + 2)/ 2;
                }
                else {
                    Z.push_back(A[i]);
                    Z.push_back(A[j - 1]);
                    ans += all - diff / 2;
                }
            }
        }
        
        else {
            while (j < n){
                Ask.push_back(A[j]);
                if (O.size() < j - i + 1 || j == n - 1) {
                    j++;
                    break;
                }
                Ask.push_back(O[j - i]);
                j++;
            }
            int diff = use_machine(Ask);
            int all = (Ask.size() + 1) / 2;
            if (diff & 1) {
                int As = (diff + 1) / 2;
                ans += As;
            }
            else {
                int diff2 = use_machine({O.front(), A[i]});
                if (diff2) {
                    Z.push_back(A[i]);
                    Z.push_back(A[j - 1]);
                    ans += (diff / 2 + 1);
                }
                else {
                    O.push_back(A[i]);
                    O.push_back(A[j - 1]);
                    ans += diff / 2;
                }
            }
        }
        
        i = j;
    }
    if (i == n - 1) {
        int diff = use_machine({Z.front(), A[i]});
        ans += 1 - diff;   
    }
    return ans;
}

Compilation message (stderr)

mushrooms.cpp: In function 'int count_mushrooms(int)':
mushrooms.cpp:50:30: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   50 |                 if (Z.size() < j - i + 1 || j == n - 1) {
      |                     ~~~~~~~~~^~~~~~~~~~~
mushrooms.cpp:81:30: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   81 |                 if (O.size() < j - i + 1 || j == n - 1) {
      |                     ~~~~~~~~~^~~~~~~~~~~
mushrooms.cpp:89:17: warning: unused variable 'all' [-Wunused-variable]
   89 |             int all = (Ask.size() + 1) / 2;
      |                 ^~~
mushrooms.cpp:43:9: warning: 'last' may be used uninitialized in this function [-Wmaybe-uninitialized]
   43 |     int i = last + 1;
      |         ^

• Subtask 1: 25 / 100