Amplitude Hackathon Summer '24 Problem 3 - Mike's Unlocked Laptop

    1#include <bits/stdc++.h>
    2using namespace std;
    3using ll = long long;
    4using i128 = __int128;
    5const int inf = 1e9;
    6const ll INF = 1e18; //❄️
    7int main() {
    8    ios::sync_with_stdio(0); cin.tie(0); 
    9    string ans = "";
    10    vector<char> chars;
    11    for (int i = 'a'; i <= 'z'; i++) chars.push_back((char) i);
    12    for (int i = 'A'; i <= 'Z'; i++) chars.push_back((char) i);
    13    for (int i = 0; i <= 9; i++) chars.push_back(i + '0');
    14    auto qry = [&](const string &s) {
    15        cout << s << endl;
    16        int n; cin >> n;
    17        return n;
    18    };
    19    for (int i = 0; i < chars.size(); i++) {
    20        if (qry(chars[i] + "") == 1) {
    21            ans += chars[i];
    22            break;
    23        }
    24    }
    25    while (1) {
    26        string cur = ans;
    27        bool ok = 0;
    28        for (int i = 0; i < chars.size(); i++) {
    29            int res = qry(cur + chars[i]);
    30            if (res == -1) return 0;
    31            if (res == cur.size() + 1) {
    32                ans += chars[i];
    33                ok = 1;
    34                break;
    35            }
    36        }
    37        if (!ok) break;
    38    }
    39    while (1) {
    40        string cur = ans;
    41        bool ok = 0;
    42        for (int i = 0; i < chars.size(); i++) {
    43            int res = qry(chars[i] + cur);
    44            if (res == -1) return 0;
    45            if (res == cur.size() + 1) {
    46                ans = chars[i] + ans;
    47                ok = 1;
    48                break;
    49            }
    50        }
    51        if (!ok) break;
    52    }
    53    return 0;
    54}