Submission #699221

#	Time	Username	Problem	Language	Result	Execution time	Memory
699221		maomao90	Colors (BOI20_colors)	C++17	9 / 100	2 ms	288 KiB

Colors

// Hallelujah, praise the one who set me free
// Hallelujah, death has lost its grip on me
// You have broken every chain, There's salvation in your name
// Jesus Christ, my living hope
#include <bits/stdc++.h> 
using namespace std;

#define REP(i, s, e) for (int i = (s); i < (e); i++)
#define RREP(i, s, e) for (int i = (s); i >= (e); i--)
template <class T>
inline bool mnto(T& a, T b) {return a > b ? a = b, 1 : 0;}
template <class T>
inline bool mxto(T& a, T b) {return a < b ? a = b, 1: 0;}
typedef long long ll;
typedef long double ld;
#define FI first
#define SE second
typedef pair<int, int> ii;
typedef pair<ll, ll> pll;
typedef tuple<int, int, int> iii;
#define ALL(_a) _a.begin(), _a.end()
#define SZ(_a) (int) _a.size()
#define pb push_back
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<ii> vii;
typedef vector<iii> viii;

#ifndef DEBUG
#define cerr if (0) cerr
#endif

const int INF = 1000000005;
const ll LINF = 1000000000000000005ll;

ll n;
vll qry;

inline bool ask(ll x) {
    cout << "? " << x << endl;
    bool r; cin >> r;
    return r;
}

int main() {
    cin >> n;
    {
    bool tog = 0;
    int s = 1;
    ask(1);
    RREP (i, n - 1, 1) {
        tog ^= 1;
        if (tog) {
            s += i;
        } else {
            s -= i;
        }
        if (!ask(s)) {
            cout << "= " << i + 1 << endl;
            return 0;
        }
    }
    cout << "= " << 1 << endl;
    return 0;
    }
    ll lo = 0, hi = n, mid;
    qry.clear();
    while (hi - lo > 1) {
        mid = lo + hi + 1 >> 1;
        qry.pb(mid);
        lo = mid;
    }
    ll lft = LINF, rht = -LINF;
    ll d = 0;
    REP (i, 0, SZ(qry)) {
        if (i & 1 ^ 1) {
            d -= qry[i];
        } else {
            d += qry[i];
        }
        mnto(lft, d);
        mxto(rht, d);
    }
    ll s = -lft + 1;
    assert(s + rht <= n);
    ask(s);
    lo = 0, hi = n;
    bool tog = 0;
    while (hi - lo > 1) {
        mid = lo + hi + 1 >> 1;
        if (!tog) {
            s -= mid;
        } else {
            s += mid;
        }
        if (s < 1 || s > n) {
            break;
        }
        assert(s >= 1 && s <= n);
        tog ^= 1;
        bool res = ask(s);
        if (res) {
            hi = mid;
        } else {
            lo = mid;
        }
    }
    cout << "= " << hi << endl;
    return 0;
}

Compilation message (stderr)

Colors.cpp: In function 'int main()':
Colors.cpp:69:23: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   69 |         mid = lo + hi + 1 >> 1;
      |               ~~~~~~~~^~~
Colors.cpp:76:15: warning: suggest parentheses around arithmetic in operand of '^' [-Wparentheses]
   76 |         if (i & 1 ^ 1) {
      |             ~~^~~
Colors.cpp:90:23: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   90 |         mid = lo + hi + 1 >> 1;
      |               ~~~~~~~~^~~

• Subtask 1: 9 / 9
• Subtask 2: 0 / 13
• Subtask 3: 0 / 21
• Subtask 4: 0 / 24
• Subtask 5: 0 / 33