Submission #686640

#	Time	Username	Problem	Language	Result	Execution time	Memory
686640		null_awe	Colors (BOI20_colors)	C++14	0 / 100	1 ms	208 KiB

Colors

#include <iostream>
#include <set>
using namespace std;

#define int long long

int n, at;
set<int> s;

bool qry(int x) {
  if (at + x <= n) at += x;
  else at -= x;
  if (s.count(at)) exit(0);
  cout << "? " << at << endl;
  s.insert(at);
  bool ans; cin >> ans;
  return ans;
}

int32_t main() {
  cin >> n;
  bool added = true;
  int left = n;
  at = 1;
  for (int i = (left + 1) / 2; i > 0; left >>= 1, i = (left + 1) / 2) {
    if (!added) at += i;
    added = !added;
    if (i == 1) break;
  }
  cout << "? " << at << endl;
  int tmp; cin >> tmp;
  s.insert(at);
  int sum = 0;
  left = n;
  for (int i = (left + 1) / 2; i > 0; left >>= 1, i = (left + 1) / 2) {
    int chg = sum + i;
    if (chg >= n) continue;
    if (!qry(chg)) sum = chg;
  }
  cout << "= " << sum + 1 << '\n';
  return 0;
}

/*
49
25
12
6
3
2
1
*/

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