Submission #494700

#	Time	Username	Problem	Language	Result	Execution time	Memory
494700		balbit	Hidden Sequence (info1cup18_hidden)	C++14	100 / 100	11 ms	300 KiB

hidden

#include <bits/stdc++.h>
#include "grader.h"
//#define int ll
using namespace std;
#define ll long long
#define y1 zck_is_king
#define pii pair<ll, ll>
#define ull unsigned ll
#define f first
#define s second
#define ALL(x) x.begin(),x.end()
#define SZ(x) (int)x.size()
#define SQ(x) (x)*(x)
#define MN(a,b) a = min(a,(__typeof__(a))(b))
#define MX(a,b) a = max(a,(__typeof__(a))(b))
#define pb push_back
#define REP(i,n) for (int i = 0; i<n; ++i)
#define RREP(i,n) for (int i = n-1; i>=0; --i)
#define REP1(i,n) for (int i = 1; i<=n; ++i)
#define SORT_UNIQUE(c) (sort(c.begin(),c.end()), c.resize(distance(c.begin(),unique(c.begin(),c.end()))))
#ifdef BALBIT
#define IOS()
#define bug(...) fprintf(stderr,"#%d (%s) = ",__LINE__,#__VA_ARGS__),_do(__VA_ARGS__);
template<typename T> void _do(T &&x){cerr<<x<<endl;}
template<typename T, typename ...S> void _do(T &&x, S &&...y){cerr<<x<<", ";_do(y...);}
#else
#define IOS() ios_base::sync_with_stdio(0);cin.tie(0);
#define endl '\n'
#define bug(...)
#endif

const int iinf = 1e9+10;
const ll inf = 1ll<<60;
const ll mod = 1e9+7 ;


void GG(){cout<<"0\n"; exit(0);}

ll mpow(ll a, ll n, ll mo = mod){ // a^n % mod
    ll re=1;
    while (n>0){
        if (n&1) re = re*a %mo;
        a = a*a %mo;
        n>>=1;
    }
    return re;
}

ll inv (ll b, ll mo = mod){
    if (b==1) return b;
    return (mo-mo/b) * inv(mo%b,mo) % mo;
}

const int maxn = 1e5+5;


using namespace std;

bool flip = 0;

#ifdef BALBIT
vector<int> yay = {0,0,0,0,0,0,0,0,0,0,0};
bool isSubsequence(vector<int> ar) {
    int at = 0;
    if (SZ(ar) == 0) return 1;
    REP(i, SZ(yay)) {
        if (yay[i] == ar[at]) {
            ++at; if (at == SZ(ar)) return 1;
        }
    }
    return 0;
}
#endif // BALBIT

bool ask(vector<int> t) {
    if (flip) {

        for (int &y : t) y ^= 1;
    }
    return isSubsequence(t);
}


vector < int > findSequence (int N)
{
    vector < int > ans (N, 0);
    int T0=0, T1=0;
    // T0 is smaller than T1
    // first figure out which is smaller
    {
        vector<int> hi;
        REP(i, (N+1)/2) {
            hi.pb(1);
        }
        if (ask(hi)) {
            flip = 0; // 1 is more common
        }else{
            flip = 1;
        }
        bug("Flip?: ",flip);
    }

    // now try to figure out number of 0s and 1s, knowing that #0 <= #1

    {
        vector<int> hi;
        while (1) {
            hi.pb(0);
            if (ask(hi)) {
                ++T0;
            }else break;
        }
    }

    T1 = N-T0;
    bug(T0, T1);
    {
        vector<int> hi;
        hi.pb(1);
        REP(i,T0) hi.pb(0);
        ans[0] = ask(hi);
    }

    int S0=0,S1=0;
    if (ans[0] == 0) ++S0;
    else ++S1;

    REP1(i,N-1) {
        if (ans[i-1]) {
            // two cases
            if (T1 - S1 + S0 < S1 + T0 - S0) {
                // do back part
                vector<int> hi;
                REP(i,S0) hi.pb(0);
                hi.pb(0); // !
                REP(i,T1-S1) hi.pb(1);
                ans[i] = !ask(hi);
            }else{
                // do front part
                vector<int> hi;
                REP(i,S1) hi.pb(1);
                hi.pb(1);
                REP(i,T0-S0) hi.pb(0);
                ans[i] = ask(hi); // if yes, means 1 is ok to put here
            }
        }else{
            // easy case
            vector<int> hi;
            REP(i, S0) hi.pb(0);
            hi.pb(1);
            REP(i, T0-S0) hi.pb(0);
            ans[i] = ask(hi); // if yes, means there's something btw here
        }
        if (ans[i] == 0) ++S0;
        else ++S1;
    }

    for (int &x : ans) x ^= flip;

    return ans;
}

#ifdef BALBIT
signed main(){
    vector<int> yo = findSequence(SZ(yay));
    for (int y : yo) cout<<y<<' ';
    cout<<endl;
    assert(yo == yay);
}
#endif

Compilation message (stderr)

grader.cpp: In function 'int main()':
grader.cpp:28:26: warning: format '%d' expects argument of type 'int', but argument 3 has type 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wformat=]
   28 |     fprintf (fifo_out, "%d\n", ans.size ());
      |                         ~^     ~~~~~~~~~~~
      |                          |              |
      |                          int            std::vector<int>::size_type {aka long unsigned int}
      |                         %ld
grader.cpp:29:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   29 |     for (int i=0; i<ans.size () && i < N; i++)
      |                   ~^~~~~~~~~~~~

• Subtask 1: 20 / 20
• Subtask 2: 80 / 80