Submission #250999

#	Time	Username	Problem	Language	Result	Execution time	Memory
250999		WhaleVomit	Three Friends (BOI14_friends)	C++14	100 / 100	18 ms	9252 KiB

friends

#include <bits/stdc++.h>
using namespace std;

#define f first
#define s second
#define pb push_back
#define mp make_pair
#define all(v) v.begin(), v.end()
#define sz(v) (int)v.size()

#define MOO(i, a, b) for(int i=a; i<b; i++)
#define M00(i, a) for(int i=0; i<a; i++)
#define MOOd(i,a,b) for(int i = (b)-1; i >= a; i--)
#define M00d(i,a) for(int i = (a)-1; i>=0; i--)

#define FAST ios::sync_with_stdio(0); cin.tie(0);
#define finish(x) return cout << x << '\n', 0;
#define dbg(x) cerr << ">>> " << #x << " = " << x << "\n";
#define _ << " _ " <<

template<class T> bool ckmin(T& a, const T& b) {return b < a ? a = b, 1 : 0;}
template<class T> bool ckmax(T& a, const T& b) {return a < b ? a = b, 1 : 0;}

typedef long long ll;
typedef long double ld;
typedef vector<int> vi;
typedef pair<int,int> pi;
typedef pair<ld,ld> pd;
typedef complex<ld> cd;

int n;
string s;

bool good(string s1, string s2) {
    int idx = 0;
    bool diff = 0;
    M00(i, sz(s2)) {
        if(idx >= sz(s1) || s2[i] != s1[idx]) {
            if(diff) return 0;
            else diff = 1;
        } else {
            idx++;
        }
    }
    if(idx != sz(s1)) diff = 0;
    //dbg(s1 _ s2 _ diff);
    return diff;
}

int main() { FAST
    cin >> n >> s;
    if(n%2 == 0) {
        finish("NOT POSSIBLE");
    }
    int k = n/2;
    string s1 = s.substr(0, k);
    set<string> res;
    if(good(s1, s.substr(k, k+1))) {
        res.insert(s1);
    }
    string s2 = s.substr(k+1, k);
    if(good(s2, s.substr(0, k+1))) {
        res.insert(s2);
    }
    if(sz(res) == 0) {
        finish("NOT POSSIBLE");
    } else if(sz(res) == 2) {
        finish("NOT UNIQUE");
    } else {
        finish(*res.begin());
    }
}

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