#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#define ll long long
#define pll pair<ll, ll>
#define pii pair<int, int>
#define pff pair<float, float>
#define coutpair(p) cout << p.first << " " << p.second << "\n"
typedef tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update> ordered_set;
typedef tree<int, null_type, less_equal<int>, rb_tree_tag, tree_order_statistics_node_update> ordered_multiset;
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int n; cin >> n;
string s; cin >> s;
unordered_map<char, int> m;
if (s.length()%2==0){
cout << "NOT POSSIBLE";
return 0;
}
int cnt = 0, occur = 0;
char nl = '2';
string ans;
for (int i=0; i<s.length(); i++) m[s[i]]++;
for (auto it : m){
if (it.second%2!=0 && it.second != nl){
cnt++;
nl = it.first;
occur = m[it.first];
}
if (cnt > 1){
cout << "NOT POSSIBLE";
return 0;
}
}
for (int i=0; i<s.length(); i++){
if (s[i] == nl){
if (m[s[i]] == 1) continue;
else if (m[s[i]] > 1){
ans += s[i];
m[s[i]]--;
continue;
}
}
else ans += s[i];
if (ans.length() == s.length()/2) break;
}
m[nl] = 0;
string ans2;
for (int i=n-1; i>=0; i--){
if (s[i] == nl) m[s[i]]++;
else ans2 += s[i];
if (m[s[i]] == nl/2) break;
}
reverse(ans2.begin(), ans2.end());
if (s[0] == nl && s[s.length()-1] == nl) cout << "NOT UNIQUE";
else if (ans == ans2) cout << ans;
else cout << "NOT POSSIBLE";
return 0;
}
Compilation message
friends.cpp: In function 'int main()':
friends.cpp:38:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
38 | for (int i=0; i<s.length(); i++) m[s[i]]++;
| ~^~~~~~~~~~~
friends.cpp:52:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
52 | for (int i=0; i<s.length(); i++){
| ~^~~~~~~~~~~
friends.cpp:34:18: warning: variable 'occur' set but not used [-Wunused-but-set-variable]
34 | int cnt = 0, occur = 0;
| ^~~~~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
0 ms |
348 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
17 ms |
6388 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
