Submission #718615

#	Time	Username	Problem	Language	Result	Execution time	Memory
718615		Sam_a17	Colors (BOI20_colors)	C++17	22 / 100	2 ms	336 KiB

Colors

#define _CRT_SECURE_NO_WARNINGS
#include <bits/stdc++.h>
//#include "temp.cpp"
#include <cstdio>
using namespace std;
 
#ifndef ONLINE_JUDGE
#define dbg(x) cerr << #x <<" "; print(x); cerr << endl;
#else
#define dbg(x)
#endif
 
#define sz(x) (int((x).size()))
#define len(x) (int)x.length()
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define clr(x) (x).clear()
#define uniq(x) x.resize(unique(all(x)) - x.begin());
#define blt(x) __builtin_popcount(x)
 
#define pb push_back
#define popf pop_front
#define popb pop_back
 
void print(long long t) {cerr << t;}
void print(int t) {cerr << t;}
void print(string t) {cerr << t;}
void print(char t) {cerr << t;}
void print(double t) {cerr << t;}
void print(long double t) {cerr << t;}
void print(unsigned long long t) {cerr << t;}
 
template <class T, class V> void print(pair <T, V> p);
template <class T> void print(vector <T> v);
template <class T> void print(set <T> v);
template <class T, class V> void print(map <T, V> v);
template <class T> void print(multiset <T> v);
template <class T, class V> void print(T v[],V n) {cerr << "["; for(int i = 0; i < n; i++) {print(v[i]); cerr << " "; } cerr << "]";}
template <class T, class V> void print(pair <T, V> p) {cerr << "{"; print(p.first); cerr << ","; print(p.second); cerr << "}";}
template <class T> void print(vector <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T> void print(deque <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T> void print(set <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T> void print(multiset <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T, class V> void print(map <T, V> v) {cerr << "[ "; for (auto i : v) {print(i); cerr << " ";} cerr << "]";}
 
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
#define nl '\n'
 
// for grid problems
int dx[8] = {-1,0,1,0,1,-1,1,-1};
int dy[8] = {0,1,0,-1,1,1,-1,-1};
 
// lowest / (1 << 17) >= 1e5 / (1 << 18) >= 2e5 / (1 << 21) >= 1e6
void fastIO() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr); cout.tie(nullptr);
}
// file in/out
void setIO(string str = "") {
  fastIO();
 
  if (str != "") {
    freopen((str + ".in").c_str(), "r", stdin);
    freopen((str + ".out").c_str(), "w", stdout);
  }
}
// Indexed Set
template <class T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
int n;
 
int ask(int curr) {
  cout << "? " << curr << endl;
  int answ; cin >> answ;
  cout.flush();
  return answ;
}
 
void out(int curr) {
  cout << "= " << curr << endl;
  // exit(0);
}
 
void solve_() {
  cin >> n;
 
 
  if(n <= 64) {
    int ans = 0, last = 1;
    ask(1);
 
    int l = 2, r = n;
 
    int i = 0;
    while(l <= r) {
      if(i % 2 == 0) {
        int p = ask(r);
        if(p) {
          ans = abs(r - last);
        }
 
        last = r;
        r--;
      } else {
        int p = ask(l);
        if(p) {
          ans = abs(l - last);
        }
 
        last = l;
        l++;
      }
 
      i++;
    }
 
    if(ans == 0) {
      ans = n;
    }
 
    out(ans);
  }
  else {
    long long ina = 1, inb = n - 1;

    vector<long long> go;
    while(ina <= inb) {
      long long mid = (ina + inb) / 2;
      go.push_back(mid);
      ina = mid + 1;
    }

    // worst scenario

    long long ind;

    int wh = 0;
    if(sz(go) % 2 == 1) {
      long long st = n;
      wh = 1;
      reverse(all(go));

      for(int i = 0; i < sz(go); i++) {
        if(i % 2 == 0) {
          st -= go[i];
        } else {
          st += go[i];
        }
      }

      ind = st;
    } else {
      long long st = 1;
      wh = 2;
      for(int i = 0; i < sz(go); i++) {
        if(i % 2 == 0) {
          st += go[i];
        } else {
          st -= go[i];
        }
      }

      ind = st;
    }


    assert(ind != -1);

    long long ans = n;
    ina = 1, inb = n - 1;

    vector<bool> vis(n + 1);
    vis[ind] = true;
    ask(ind);

    int it = 0;

    if(wh == 1) {
      it = 0;
    } else {
      it = 1;
    }

    while(ina <= inb) {
      long long mid = (ina + inb) / 2;
      if(it % 2 == 0) {
        assert(ind + mid <= n && !vis[ind + mid]);
        ind += mid;
        vis[ind] = true;
        int p = ask(ind);
        
        if(p) {
          ans = mid;
          inb = mid - 1;
        } else {
          ina = mid + 1;
        }
      } else {
        assert(ind - mid >= 1 && !vis[ind - mid]);
        ind -= mid;
        vis[ind] = true;
        int p = ask(ind);
        
        if(p) {
          ans = mid;
          inb = mid - 1;
        } else {
          ina = mid + 1;
        }
      } 
      it++;
    }

    out(ans);
  }
}
 
int main() {
  setIO();
 
  auto solve = [&](int test_case)-> void {
    while(test_case--) {
      solve_();
    }
  };
 
  int test_cases = 1;
  // cin >> test_cases;
  solve(test_cases);
 
  return 0;
} 

Compilation message (stderr)

Colors.cpp: In function 'void setIO(std::string)':
Colors.cpp:64:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   64 |     freopen((str + ".in").c_str(), "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Colors.cpp:65:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   65 |     freopen((str + ".out").c_str(), "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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