Submission #687037

#	Time	Username	Problem	Language	Result	Execution time	Memory
687037		null_awe	Colors (BOI20_colors)	C++14	100 / 100	4 ms	376 KiB

Colors

#include <iostream>
using namespace std;

#define int long long

int n, at;
bool up = true;

bool qry(int x) {
  at += up ? x : -x, up = !up;
  cout << "? " << at << endl;
  bool ans; cin >> ans;
  return ans;
}

int32_t main() {
  cin >> n;
  bool added = true;
  int l = 0, r = n;
  at = 1;
  while (l < r - 1) {
    l = (l + r) / 2;
    int keep = l;
    l = (l + r) / 2, at += (l - keep);
  }
  cout << "? " << at << endl;
  int tmp; cin >> tmp;
  int lo = 0, hi = n;
  while (lo < hi - 1) {
    int mid = (lo + hi) >> 1;
    if (qry(mid)) hi = mid;
    else lo = mid;
  }
  cout << "= " << hi << '\n';
  return 0;
}

Compilation message (stderr)

Colors.cpp: In function 'int32_t main()':
Colors.cpp:18:8: warning: unused variable 'added' [-Wunused-variable]
   18 |   bool added = true;
      |        ^~~~~

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