#include <bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define mp make_pair
#define pb push_back
#define pf push_front
#define iter(v, i) for (__typeof__((v).begin()) i = (v).begin(); i != (v).end(); i++)
#define fast_io_without_cstdio ios_base::sync_with_stdio(false), cin.tie(NULL)
#define all(v) (v).begin(), (v).end()
#define rep(i, s, e) for (int i = s; i < e; i++)
#ifdef __linux__
#define gc getchar_unlocked
#define pc putchar_unlocked
#else
#define gc getchar
#define pc putchar
#endif
#if __cplusplus <= 199711L
template<class BidirIt>
BidirIt prev(BidirIt it, typename iterator_traits<BidirIt>::difference_type n = 1) {
advance(it, -n);
return it;
}
template<class ForwardIt>
ForwardIt next(ForwardIt it, typename iterator_traits<ForwardIt>::difference_type n = 1) {
advance(it, n);
return it;
}
#endif
typedef long long ll;
typedef pair<int, int> ii;
typedef vector<int> vi;
typedef vector<ii> vii;
typedef long double ldouble;
const double EPS = 1e-9;
const double PI = 3.141592653589793238462;
template<typename T>
inline T sq(T a) { return a * a; }
//#ifdef LOCAL_MACHINE
//#endif
const int MAXN = 2e6 + 5;
const int BASE = 29;
const int MOD = 1e9 + 7;
inline int mul_mod(int a, int b) {
return a * 1LL * b % MOD;
}
inline void add_mod(int &a, int b) {
a += b;
if (a >= MOD) a -= MOD;
}
inline void sub_mod(int &a, int b) {
a -= b;
if (a < 0) a += MOD;
}
char str[MAXN];
int h[MAXN], bpow[MAXN];
int get_hash(int i, int j) {
int ret = h[j];
sub_mod(ret, mul_mod(h[i - 1], bpow[j - i + 1]));
return ret;
}
int main() {
bpow[0] = 1;
for (int i = 1; i < MAXN; i++)
bpow[i] = mul_mod(bpow[i - 1], BASE);
//freopen("", "r", stdin);
//freopen("", "w", stdout);
int n;
scanf("%d", &n);
scanf("%s", str + 1);
if (!(n & 1)) {
puts("NOT POSSIBLE");
return 0;
}
for (int i = 1; i <= n; i++) {
h[i] = mul_mod(h[i - 1], BASE);
add_mod(h[i], str[i] - 'A' + 1);
}
int ans = -1, cnt = 0;
for (int i = 1; i <= n; i++) {
int left, right;
if (i <= (n / 2) + 1) {
left = get_hash(1, i - 1);
left = mul_mod(left, bpow[(n / 2) - (i - 1)]);
add_mod(left, get_hash(i + 1, i + 1 + (n / 2) - (i - 1) - 1));
right = get_hash(n - (n / 2) + 1, n);
} else {
left = get_hash(1, n / 2);
int len = n - (i + 1) + 1;
right = get_hash((n / 2) + 1, (n / 2) + 1 + (n / 2) - len - 1);
right = mul_mod(right, bpow[len]);
add_mod(right, get_hash(i + 1, n));
}
if (left == right) {
cnt++;
ans = i;
//printf("I can replace char at pos %d\n", i);
}
}
if (cnt > 1)
puts("NOT UNIQUE");
else if (cnt == 0)
puts("NOT POSSIBLE");
else {
for (int i = 1, c = 0; c < (n / 2); i++) {
if (ans == i) continue;
c++;
pc(str[i]);
}
pc('\n');
}
return 0;
}
Compilation message
sequence.cpp: In function 'int main()':
sequence.cpp:86:20: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
scanf("%d", &n);
^
sequence.cpp:87:25: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
scanf("%s", str + 1);
^
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
19 ms |
19596 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
9 ms |
19596 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
13 ms |
19596 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
9 ms |
19596 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
