#include <bits/stdc++.h>
#define pii pair<int, int>
#define x first
#define y second
using namespace std;
// I will use hsh 107, 109
const int N = 2e6+5, M = 1e9+7;
int n, st;
char A[N];
pii hsh[N], pw[N], iden(1000000007, 1000000009);
pii add(pii a, pii b) { return pii(a.x + b.x, a.y + b.y); }
pii mul(pii a, pii b) { return pii(a.x * b.x, a.y * b.y); }
pii sub(pii a, pii b) { return pii(a.x - b.x, a.y - b.y); }
int main() {
scanf("%d", &n);
scanf("%s", A+1);
st = n >> 1;
for(int i = 1; i <= n; ++i) hsh[i] = add(mul(hsh[i-1], iden), pii(A[i], A[i]));
pw[0] = pii(1, 1);
for(int i = 1; i <= n; ++i) pw[i] = mul(pw[i-1], iden);
set<pii> V;
for(int i = 1; i <= n; ++i) {
pii hshl, hshr;
if(i <= st) {
hshl = add(mul(hsh[i-1], pw[st-i+1]), sub(hsh[st+1], mul(hsh[i], pw[st-i+1])));
hshr = sub(hsh[n], mul(hsh[st+1], pw[st]));
if(hshl == hshr) V.emplace(st+2, n);
} else {
hshl = hsh[st];
hshr = add(sub(hsh[n], mul(hsh[i], pw[n-i])),
mul(sub(hsh[i-1], mul(hsh[st], pw[i-st-1])), pw[n-i]));
if(hshl == hshr) V.emplace(1, st);
}
}
bool hell = true;
for(int i = 1; i <= st; ++i) hell &= A[i] == A[st+i+1];
if(V.size() == 0 or n % 2 == 0) puts("NOT POSSIBLE");
else if(V.size() == 1 || hell) A[V.begin()->y+1] = 0, puts(A+V.begin()->x);
else if(V.size() > 1) puts("NOT UNIQUE");
}
Compilation message
friends.cpp: In function 'int main()':
friends.cpp:19:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
scanf("%d", &n);
~~~~~^~~~~~~~~~
friends.cpp:20:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
scanf("%s", A+1);
~~~~~^~~~~~~~~~~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
2 ms |
376 KB |
Output is correct |
| 2 |
Correct |
2 ms |
376 KB |
Output is correct |
| 3 |
Correct |
2 ms |
428 KB |
Output is correct |
| 4 |
Correct |
2 ms |
428 KB |
Output is correct |
| 5 |
Correct |
2 ms |
428 KB |
Output is correct |
| 6 |
Correct |
2 ms |
428 KB |
Output is correct |
| 7 |
Correct |
2 ms |
428 KB |
Output is correct |
| 8 |
Correct |
2 ms |
428 KB |
Output is correct |
| 9 |
Correct |
2 ms |
480 KB |
Output is correct |
| 10 |
Correct |
2 ms |
480 KB |
Output is correct |
| 11 |
Correct |
2 ms |
480 KB |
Output is correct |
| 12 |
Correct |
2 ms |
480 KB |
Output is correct |
| 13 |
Correct |
2 ms |
480 KB |
Output is correct |
| 14 |
Correct |
2 ms |
480 KB |
Output is correct |
| 15 |
Correct |
2 ms |
532 KB |
Output is correct |
| 16 |
Correct |
2 ms |
532 KB |
Output is correct |
| 17 |
Correct |
2 ms |
532 KB |
Output is correct |
| 18 |
Correct |
2 ms |
532 KB |
Output is correct |
| 19 |
Correct |
2 ms |
532 KB |
Output is correct |
| 20 |
Correct |
2 ms |
532 KB |
Output is correct |
| 21 |
Correct |
2 ms |
532 KB |
Output is correct |
| 22 |
Correct |
2 ms |
540 KB |
Output is correct |
| 23 |
Correct |
2 ms |
544 KB |
Output is correct |
| 24 |
Correct |
2 ms |
556 KB |
Output is correct |
| 25 |
Correct |
2 ms |
556 KB |
Output is correct |
| 26 |
Correct |
2 ms |
556 KB |
Output is correct |
| 27 |
Correct |
2 ms |
556 KB |
Output is correct |
| 28 |
Correct |
2 ms |
556 KB |
Output is correct |
| 29 |
Correct |
2 ms |
556 KB |
Output is correct |
| 30 |
Correct |
2 ms |
556 KB |
Output is correct |
| 31 |
Correct |
2 ms |
672 KB |
Output is correct |
| 32 |
Correct |
2 ms |
672 KB |
Output is correct |
| 33 |
Correct |
2 ms |
724 KB |
Output is correct |
| 34 |
Correct |
2 ms |
724 KB |
Output is correct |
| 35 |
Correct |
2 ms |
728 KB |
Output is correct |
| 36 |
Correct |
2 ms |
728 KB |
Output is correct |
| 37 |
Correct |
2 ms |
728 KB |
Output is correct |
| 38 |
Correct |
2 ms |
728 KB |
Output is correct |
| 39 |
Correct |
2 ms |
728 KB |
Output is correct |
| 40 |
Correct |
2 ms |
728 KB |
Output is correct |
| 41 |
Correct |
2 ms |
728 KB |
Output is correct |
| 42 |
Correct |
2 ms |
728 KB |
Output is correct |
| 43 |
Correct |
2 ms |
728 KB |
Output is correct |
| 44 |
Correct |
2 ms |
728 KB |
Output is correct |
| 45 |
Correct |
2 ms |
728 KB |
Output is correct |
| 46 |
Correct |
2 ms |
728 KB |
Output is correct |
| 47 |
Correct |
2 ms |
728 KB |
Output is correct |
| 48 |
Correct |
2 ms |
728 KB |
Output is correct |
| 49 |
Correct |
2 ms |
728 KB |
Output is correct |
| 50 |
Correct |
2 ms |
728 KB |
Output is correct |
| 51 |
Correct |
2 ms |
728 KB |
Output is correct |
| 52 |
Correct |
2 ms |
728 KB |
Output is correct |
| 53 |
Correct |
2 ms |
728 KB |
Output is correct |
| 54 |
Correct |
2 ms |
728 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
49 ms |
34796 KB |
Output is correct |
| 2 |
Correct |
47 ms |
34840 KB |
Output is correct |
| 3 |
Correct |
51 ms |
34864 KB |
Output is correct |
| 4 |
Correct |
48 ms |
34880 KB |
Output is correct |
| 5 |
Correct |
49 ms |
34880 KB |
Output is correct |
| 6 |
Correct |
49 ms |
35968 KB |
Output is correct |
| 7 |
Correct |
288 ms |
38916 KB |
Output is correct |
| 8 |
Correct |
44 ms |
38916 KB |
Output is correct |
| 9 |
Correct |
46 ms |
38936 KB |
Output is correct |
| 10 |
Correct |
49 ms |
40684 KB |
Output is correct |
| 11 |
Correct |
43 ms |
40684 KB |
Output is correct |
| 12 |
Correct |
3 ms |
40684 KB |
Output is correct |
| 13 |
Correct |
2 ms |
40684 KB |
Output is correct |
| 14 |
Correct |
2 ms |
40684 KB |
Output is correct |
| 15 |
Correct |
2 ms |
40684 KB |
Output is correct |
| 16 |
Correct |
2 ms |
40684 KB |
Output is correct |
| 17 |
Correct |
2 ms |
40684 KB |
Output is correct |
| 18 |
Correct |
3 ms |
40684 KB |
Output is correct |
| 19 |
Correct |
2 ms |
40684 KB |
Output is correct |
| 20 |
Correct |
2 ms |
40684 KB |
Output is correct |
| 21 |
Correct |
2 ms |
40684 KB |
Output is correct |
| 22 |
Correct |
2 ms |
40684 KB |
Output is correct |
| 23 |
Correct |
2 ms |
40684 KB |
Output is correct |
| 24 |
Correct |
2 ms |
40684 KB |
Output is correct |
| 25 |
Correct |
2 ms |
40684 KB |
Output is correct |
| 26 |
Correct |
2 ms |
40684 KB |
Output is correct |
| 27 |
Correct |
2 ms |
40684 KB |
Output is correct |
| 28 |
Correct |
2 ms |
40684 KB |
Output is correct |
| 29 |
Correct |
2 ms |
40684 KB |
Output is correct |
| 30 |
Correct |
2 ms |
40684 KB |
Output is correct |
| 31 |
Correct |
2 ms |
40684 KB |
Output is correct |
| 32 |
Correct |
2 ms |
40684 KB |
Output is correct |
| 33 |
Correct |
2 ms |
40684 KB |
Output is correct |
| 34 |
Correct |
2 ms |
40684 KB |
Output is correct |
| 35 |
Correct |
2 ms |
40684 KB |
Output is correct |
| 36 |
Correct |
2 ms |
40684 KB |
Output is correct |
| 37 |
Correct |
2 ms |
40684 KB |
Output is correct |
| 38 |
Correct |
2 ms |
40684 KB |
Output is correct |
| 39 |
Correct |
2 ms |
40684 KB |
Output is correct |
| 40 |
Correct |
2 ms |
40684 KB |
Output is correct |
| 41 |
Correct |
2 ms |
40684 KB |
Output is correct |
| 42 |
Correct |
2 ms |
40684 KB |
Output is correct |
| 43 |
Correct |
2 ms |
40684 KB |
Output is correct |
| 44 |
Correct |
2 ms |
40684 KB |
Output is correct |
| 45 |
Correct |
2 ms |
40684 KB |
Output is correct |
| 46 |
Correct |
2 ms |
40684 KB |
Output is correct |
| 47 |
Correct |
2 ms |
40684 KB |
Output is correct |
| 48 |
Correct |
2 ms |
40684 KB |
Output is correct |
| 49 |
Correct |
2 ms |
40684 KB |
Output is correct |
| 50 |
Correct |
2 ms |
40684 KB |
Output is correct |
| 51 |
Correct |
2 ms |
40684 KB |
Output is correct |
| 52 |
Correct |
2 ms |
40684 KB |
Output is correct |
| 53 |
Correct |
2 ms |
40684 KB |
Output is correct |
| 54 |
Correct |
2 ms |
40684 KB |
Output is correct |
