Submission #595817

#	Time	Username	Problem	Language	Result	Execution time	Memory
595817		MadokaMagicaFan	Counting Mushrooms (IOI20_mushrooms)	C++14	92.62 / 100	12 ms	448 KiB

mushrooms

#include <bits/stdc++.h>

using namespace std;

using ll = long long;
using vi = vector<int>;
using pi = pair<int,int>;

#define all(v)          v.begin(),v.end()
#define sort(v)         sort(all(v))
#define endl            '\n'
#define forn(i,n)       for(int i = 0; i < n; ++i)
#define forbe(i,b,e)    for(int i = b; i < e; ++i)
#define forr(i,n)       for(int i = n-1; i >= 0; --i)
#define sz(v)           ((int)v.size())
#define pb              push_back
#define f               first
#define s               second

const int S = 82;

int use_machine(vi x);

int count_mushrooms(int n) {
    int j, i, val, ans = 0, pnt = 3;

    if (n < 230) {
        for (i = 1; i < n; ++i) ans += (1 - use_machine({0,i}));
        return ans+1;
    }

    vi a, b, ask;
    a.pb(0);
    for (i = 1; i < 3; ++i)
        if (use_machine({0,i})) b.pb(i);
        else a.pb(i);

    if (sz(b) > sz(a))
        swap(a,b);

    for (i = 0; i < S; ++i) {
        ask.clear();
        ask = {a[0], pnt++, a[1], pnt++};
        val = use_machine(ask);
        if (val&1) b.pb(pnt-1);
        else       a.pb(pnt-1);
        if (val&2) b.pb(pnt-2);
        else       a.pb(pnt-2);
    }

    if (a[0] != 0) swap(a,b);
    ans = sz(a);


    while (pnt < n) {
        ask.clear();
        if (sz(a) > sz(b)) {
            while (pnt < n && sz(ask) < (sz(a)<<1)) {
                ask.pb(a[sz(ask)>>1]);
                ask.pb(pnt++);
            }

            ans += (sz(ask)>>1);
            val = use_machine(ask);

            ans -= ((val+1)>>1);

            if (val&1) 
                b.pb(ask[sz(ask)-1]);
            else
                a.pb(ask[sz(ask)-1]);
        } else {
            while (pnt < n && sz(ask) < (sz(b)<<1)) {
                ask.pb(b[sz(ask)>>1]);
                ask.pb(pnt++);
            }

            val = use_machine(ask);
            ans += ((val+1)>>1);

            if (val&1) 
                a.pb(ask[sz(ask)-1]);
            else
                b.pb(ask[sz(ask)-1]);
        }
    }
    return ans;
}

#ifdef ONPC
vi rans;

int cnt = 0;

int use_machine(vi x){
    ++ cnt;
    int _ans = 0;
//    cout << "ASK: ";
//    forn(i , sz(x))
//        cout << x[i] << ' ';
//        cout << endl;
    forn(i , sz(x)-1)
        if (rans[x[i]] != rans[x[i+1]])
            ++_ans;
//    cout << "ANSWER: " << _ans << endl;
    return _ans;
}

void solve() {
    int n;
    cin >> n;

    rans.resize(n);

    char c;

    int ranswer = 0;

    forn(i, n) {
        cin >> c;
        rans[i]=(c=='A');

        if (c=='A') ++ranswer;
    }

    int cans = count_mushrooms(n);

    /* if (cans != ranswer) */
    /*     forn(i, n) */
    /*         cout << rans[i] << ' '; */

    cout << endl;
    cout << cans << ' ' << ranswer << endl;
    cout << n << ' ' << cnt << endl;
}

int main() {
//    freopen("in", "r", stdin);
//    ios_base::sync_with_stdio(0);cin.tie(0);
    solve();
}
#endif

Compilation message (stderr)

mushrooms.cpp: In function 'int count_mushrooms(int)':
mushrooms.cpp:25:9: warning: unused variable 'j' [-Wunused-variable]
   25 |     int j, i, val, ans = 0, pnt = 3;
      |         ^

• Subtask 1: 92.623 / 100