Submission #998434

#	Time	Username	Problem	Language	Result	Execution time	Memory
998434		cnn008	Combo (IOI18_combo)	C++17	10 / 100	39 ms	1104 KiB

combo

#include "bits/stdc++.h"
#include "combo.h"
using namespace std;

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
int rand(int l, int r){
    assert(l<=r);
    return uniform_int_distribution<int> (l,r)(rng);
}

string push_top(string &s, char c){
  reverse(s.begin(),s.end());
  s.push_back(c);
  reverse(s.begin(),s.end());
  return s;
}
string pop_top(string &s){
  reverse(s.begin(),s.end());
  s.pop_back();
  reverse(s.begin(),s.end());
  return s;
}
string guess_sequence(int n) {
  char c[]={'A','B','X','Y'};
  string s;
  while(1){
    if((int)s.size()==n) break;
    bool f=0;
    vector <int> p(4);
    iota(p.begin(),p.end(),0);
    shuffle(p.begin(),p.end(),rng);
    for(int i=0; i<4; i++){
      s.push_back(c[p[i]]);
      if(press(s)==(int)s.size()){
        f=1;
        break;
      }else s.pop_back();
    }
    if(!f) break;
  }
  while(1){
    if((int)s.size()==n) break;
    bool f=0;
    for(int i=0; i<4; i++){
      s=push_top(s,c[i]);
      if(press(s)==(int)s.size()){
        f=1;
        break;
      }else s=pop_top(s);
    }
    if(!f) break;
  }
  return s;
}

• Subtask 1: 5 / 5
• Subtask 2: 5 / 95