#include <bits/stdc++.h> using namespace std; using ll = long long; using ld = long double; #define fi first #define se second #define vi vector<int> #define vll vector<long long> #define pii pair<int, int> #define pll pair<long long, long long> #define pb push_back #define mp make_pair #define eb emplace_back #define all(x) (x).begin(), (x).end() #define sz(x) (int)(x).size() mt19937 rng(chrono::high_resolution_clock::now().time_since_epoch().count()); mt19937_64 rng64(chrono::high_resolution_clock::now().time_since_epoch().count()); inline int rand(int l,int r){return uniform_int_distribution<int>(l, r)(rng);} inline ll rand(ll l,ll r){return uniform_int_distribution<ll>(l, r)(rng64);} #ifdef DEBUG auto&operator<<(auto&o,pair<auto,auto>p){return o<<"("<<p.first<<", "<<p.second<<")";} auto operator<<(auto&o,auto x)->decltype(x.end(),o){o<<"{";int i=0;for(auto e:x)o<<","+!i++<<e;return o<<"}";} #define debug(X...)cerr<<"["#X"]: ",[](auto...$){((cerr<<$<<"; "),...)<<endl;}(X) #else #define debug(...){} #endif struct custom_hash { static uint64_t splitmix64(uint64_t x) { x += 0x9e3779b97f4a7c15; x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9; x = (x ^ (x >> 27)) * 0x94d049bb133111eb; return x ^ (x >> 31); } size_t operator()(uint64_t x) const { static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count(); return splitmix64(x + FIXED_RANDOM); } }; struct pair_hash{ size_t operator()(const pair<int,int>&x)const{ return hash<long long>()(((long long)x.first)^(((long long)x.second)<<32)); } }; int query(string str); int Cnt[30]; int N; bool comp(pair<string, int> x, pair<string, int> y){ if(x.fi == y.fi){ return 1; } string now = {}; for(int i = 1; i <= x.se; i++){ now += x.fi; } for(int i = y.se; i <= Cnt[y.fi[0] - 'a']; i++){ now += y.fi; } if(sz(now) > N){ return 0; } if(query(now) == sz(now)){ return 1; } return 0; } vector<pair<string, int>> vec = {}; void mergeSort(int l, int p){ if(p <= l){ return; } int mid = (l + p) / 2; mergeSort(l, mid); mergeSort(mid + 1, p); vector<pair<string, int>> a = {}; vector<pair<string, int>> b = {}; vector<pair<string, int>> res = {}; for(int i = l; i <= p; i++){ if(i <= mid){ a.pb(vec[i]); }else{ b.pb(vec[i]); } } int wsk1 = 0; int wsk2 = 0; while(wsk1 < sz(a) || wsk2 < sz(b)){ if(wsk1 == sz(a)){ res.pb(b[wsk2++]); }else if(wsk2 == sz(b)){ res.pb(a[wsk1++]); }else{ if(comp(a[wsk1], b[wsk2])){ res.pb(a[wsk1++]); }else{ res.pb(b[wsk2++]); } } } for(int i = 0; i < sz(res); i++){ vec[l + i] = res[i]; } } string guess(int n, int S){ N = n; for(int i = 0; i < S; i++){ char curr = 'a' + i; //cerr << curr << '\n'; string add = "f"; add[0] = curr; string now = add; while(query(now) == sz(now)){ now += add; } now.pop_back(); //cerr << i << ' ' << now << '\n'; Cnt[i] = sz(now); for(int j = 0; j < sz(now); j++){ vec.pb(mp(add, j + 1)); } } mergeSort(0, sz(vec) - 1); string s = ""; for(auto ele : vec){ s += ele.fi; } return s; }