Submission #1112251

#	Time	Username	Problem	Language	Result	Execution time	Memory
1112251		lucascgar	Three Friends (BOI14_friends)	C++17	100 / 100	23 ms	8364 KiB

friends

#include <bits/stdc++.h>

using namespace std;

/*
resposta ta na metade esquerda ou na metade direita
*/

typedef pair<int, int> pii;
typedef pair<long long, long long> pll;
typedef pair<long double, long double> pdd;

const int MAXN = 2e6+11;

int q[27];  // A = 0

bool check(string &c, string &o){
    // cerr << c << ' ' << o << '\n';
    bool s = 0;
    int j = 0;
    for (int i=0;i<c.size();i++){
        char x = c[i];
        if (o[j] == x){
            j++;
            continue;
        }
        if (s) return 0;
        s=1, j++, i--;
    }

    return 1;

}

signed main(){
    std::ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    int n;
    cin >> n;
    string s;
    cin >> s;
    for (auto &x:s) q[x-'A']++;
    int qo = 0, tg;
    for (int i=0;i<26;i++) if (q[i]%2==1){
        qo++, tg=i;
    }

    if (s.size()%2 == 0 || qo>1){
        cout << "NOT POSSIBLE\n";
        return 0;
    }

    set<string> fans;
    int sz = n/2;

    string st, o;
    for (int i=0;i<sz;i++){
        st.push_back(s[i]);
    }
    for (int i=sz;i<n;i++) o.push_back(s[i]);

    if (check(st, o)) fans.insert(st);

    st.clear();
    o.clear();

    for (int i=0;i<=sz;i++) o.push_back(s[i]);
    for (int i=sz+1;i<n;i++) st.push_back(s[i]);
    if (check(st, o)) fans.insert(st);

    if (fans.empty()){
        cout << "NOT POSSIBLE\n";
    }else if (fans.size()>1){
        cout << "NOT UNIQUE\n";
    }else{
        cout << *fans.begin() << '\n';
    }

    return 0;
}

Compilation message (stderr)

friends.cpp: In function 'bool check(std::string&, std::string&)':
friends.cpp:21:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   21 |     for (int i=0;i<c.size();i++){
      |                  ~^~~~~~~~~
friends.cpp: In function 'int main()':
friends.cpp:44:17: warning: variable 'tg' set but not used [-Wunused-but-set-variable]
   44 |     int qo = 0, tg;
      |                 ^~

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