Submission #961730

#	Time	Username	Problem	Language	Result	Execution time	Memory
961730		mannshah1211	Three Friends (BOI14_friends)	C++17	100 / 100	31 ms	11136 KiB

friends

/**
 *  author: hashman
 *  created: 
**/

#include <bits/stdc++.h>

using namespace std;

string to_string(string s) {
  return '"' + s + '"';
}

string to_string(const char* s) {
  return to_string((string) s);
}

string to_string(bool b) {
  return (b ? "true" : "false");
}

template <typename A, typename B>
string to_string(pair<A, B> p) {
  return "(" + to_string(p.first) + ", " + to_string(p.second) + ")";
}

template <typename A>
string to_string(A v) {
  bool first = true;
  string res = "{";
  for (const auto &x : v) {
   if (!first) {
    res += ", ";
   }
   first = false;
   res += to_string(x);
  }
  res += "}";
  return res;
}

void debug_out() {
  cerr << endl;
}

template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
  cerr << " " << to_string(H);
  debug_out(T...);
}

#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__);

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n;
  cin >> n;
  string s;
  cin >> s;
  if (n % 2 == 0) {
    cout << "NOT POSSIBLE\n";
    return 0;
  }
  auto ok = [&](string cnd) {
    vector<int> gcnd(26);
    for (char ch : cnd) {
      gcnd[ch - 'A'] -= 2;
    }
    for (char ch : s) {
      gcnd[ch - 'A']++;
    }
    if (count(gcnd.begin(), gcnd.end(), 1) != 1 || count(gcnd.begin(), gcnd.end(), 0) != 25) {
      return false;
    }
    string res = cnd + cnd;
    int j = -1;
    for (char ch : res) {
      bool found = false;
      j++;
      if (s[j] == ch) {
        found = true;
      }
      while (j < n && s[j] != ch) {
        ++j;
        if (j < n && s[j] == ch) {
          found = true;
        }
      }
      if (!found) {
        return false;
      }
    }
    return true;
  };
  string first, second;
  for (int i = (n + 1) / 2; i < n; i++) {
    first += s[i];
  }
  for (int i = 0; i < (n - 1) / 2; i++) {
    second += s[i];
  }
  int cnt = ok(first) + ok(second);
  if (cnt == 2) {
    if (first == second) {
      cout << first << '\n';
    } else {
      cout << "NOT UNIQUE\n";
    }
  } else if (cnt == 1) {
    if (ok(first)) {
      cout << first << '\n';
    } else {
      cout << second << '\n';
    }
  } else {
    cout << "NOT POSSIBLE\n";
  }
}

• Subtask 1: 35 / 35
• Subtask 2: 65 / 65