#include <bits/stdc++.h>
using namespace std;
#define rep(i,a,n) for (int i=a;i<n;i++)
#define per(i,a,n) for (int i=n-1;i>=a;i--)
#define pb push_back
#define mp make_pair
#define all(x) (x).begin(),(x).end()
#define fi first
#define se second
#define SZ(x) ((int)(x).size())
typedef vector<int> VI;
typedef long long ll;
typedef pair<int,int> PII;
typedef double db;
mt19937 mrand(random_device{}());
const ll mod1=998244353;
const ll mod2=1000000007;
int rnd(int x) { return mrand() % x;}
//ll powmod(ll a,ll b) {ll res=1;a%=mod; assert(b>=0); for(;b;b>>=1){if(b&1)res=res*a%mod;a=a*a%mod;}return res;}
ll gcd(ll a,ll b) { return b?gcd(b,a%b):a;}
// head
const int N=2000005;
const int p1=777777;
const int p2=9973;
int n;
char s[N];
ll pw1[N],hsh1[N];
ll pw2[N],hsh2[N];
ll get1(int l,int r) {
ll pp=hsh1[r]-(hsh1[l-1]*pw1[r-l+1]%mod1);
if (pp<0) pp+=mod1;
return pp;
}
ll get2(int l,int r) {
ll pp=hsh2[r]-(hsh2[l-1]*pw2[r-l+1]%mod2);
if (pp<0) pp+=mod2;
return pp;
}
bool check(int l1,int r1,int l2,int r2) {
return get1(l1,r1)==get1(l2,r2)&&get2(l1,r1)==get2(l2,r2);
}
int main() {
scanf("%d",&n);
scanf("%s",s+1);
hsh1[0]=0;
pw1[0]=1;
rep(i,1,n+1) {
pw1[i]=(pw1[i-1]*p1)%mod1;
hsh1[i]=((hsh1[i-1]*p1)+s[i])%mod1;
}
hsh2[0]=0;
pw2[0]=1;
rep(i,1,n+1) {
pw2[i]=(pw2[i-1]*p2)%mod2;
hsh2[i]=((hsh2[i-1]*p2)+s[i])%mod2;
}
if (n%2==0) {
puts("NOT POSSIBLE");
return 0;
}
VI ans;
rep(i,1,n+1) {
if (i==n/2+1) {
if (check(1,i-1,i+1,n)) ans.pb(i);
} else if (i<=n/2) {
if (i==1) {
if (check(i+1,i+n/2,i+n/2+1,n)) ans.pb(i);
} else {
if (check(1,i-1,n/2+2,n/2+i)&&check(i+1,n/2+1,n/2+i+1,n)) ans.pb(i);
}
} else {
if (i==n) {
if (check(1,n/2,n/2+1,n-1)) ans.pb(i);
} else {
if (check(1,i-(n/2+1),n/2+1,i-1)&&check(i-(n/2+1)+1,n/2,i+1,n)) ans.pb(i);
}
}
}
map<int,int> mapcina;
rep(i,0,SZ(ans)) {
if (ans[i]<=n/2) mapcina[get1(n-n/2+1,n)]++;
else mapcina[get1(1,n/2)]++;
}
if (SZ(mapcina)>1) {
puts("NOT UNIQUE");
return 0;
}
if (ans.empty()) {
puts("NOT POSSIBLE");
return 0;
}
rep(i,1,n/2+1+(ans[0]<=n/2)) {
if (i==ans[0]) continue;
printf("%c",s[i]);
}
}
Compilation message
friends.cpp: In function 'int main()':
friends.cpp:44:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
44 | scanf("%d",&n);
| ~~~~~^~~~~~~~~
friends.cpp:45:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
45 | scanf("%s",s+1);
| ~~~~~^~~~~~~~~~
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
332 KB |
Output is correct |
2 |
Correct |
0 ms |
332 KB |
Output is correct |
3 |
Correct |
0 ms |
332 KB |
Output is correct |
4 |
Correct |
0 ms |
332 KB |
Output is correct |
5 |
Correct |
0 ms |
332 KB |
Output is correct |
6 |
Correct |
0 ms |
284 KB |
Output is correct |
7 |
Correct |
0 ms |
332 KB |
Output is correct |
8 |
Correct |
0 ms |
332 KB |
Output is correct |
9 |
Correct |
0 ms |
332 KB |
Output is correct |
10 |
Correct |
0 ms |
332 KB |
Output is correct |
11 |
Correct |
0 ms |
332 KB |
Output is correct |
12 |
Correct |
0 ms |
332 KB |
Output is correct |
13 |
Correct |
0 ms |
332 KB |
Output is correct |
14 |
Correct |
0 ms |
332 KB |
Output is correct |
15 |
Correct |
0 ms |
332 KB |
Output is correct |
16 |
Correct |
0 ms |
332 KB |
Output is correct |
17 |
Correct |
1 ms |
352 KB |
Output is correct |
18 |
Correct |
1 ms |
332 KB |
Output is correct |
19 |
Correct |
0 ms |
332 KB |
Output is correct |
20 |
Correct |
0 ms |
332 KB |
Output is correct |
21 |
Correct |
0 ms |
332 KB |
Output is correct |
22 |
Correct |
0 ms |
332 KB |
Output is correct |
23 |
Correct |
0 ms |
296 KB |
Output is correct |
24 |
Correct |
0 ms |
332 KB |
Output is correct |
25 |
Correct |
0 ms |
332 KB |
Output is correct |
26 |
Correct |
0 ms |
332 KB |
Output is correct |
27 |
Correct |
0 ms |
332 KB |
Output is correct |
28 |
Correct |
0 ms |
332 KB |
Output is correct |
29 |
Correct |
0 ms |
332 KB |
Output is correct |
30 |
Correct |
0 ms |
332 KB |
Output is correct |
31 |
Correct |
1 ms |
332 KB |
Output is correct |
32 |
Correct |
0 ms |
332 KB |
Output is correct |
33 |
Correct |
0 ms |
332 KB |
Output is correct |
34 |
Correct |
0 ms |
332 KB |
Output is correct |
35 |
Correct |
0 ms |
332 KB |
Output is correct |
36 |
Correct |
0 ms |
332 KB |
Output is correct |
37 |
Correct |
0 ms |
332 KB |
Output is correct |
38 |
Correct |
0 ms |
332 KB |
Output is correct |
39 |
Correct |
0 ms |
332 KB |
Output is correct |
40 |
Correct |
0 ms |
332 KB |
Output is correct |
41 |
Correct |
0 ms |
332 KB |
Output is correct |
42 |
Correct |
0 ms |
332 KB |
Output is correct |
43 |
Correct |
0 ms |
332 KB |
Output is correct |
44 |
Correct |
1 ms |
332 KB |
Output is correct |
45 |
Correct |
1 ms |
332 KB |
Output is correct |
46 |
Correct |
0 ms |
332 KB |
Output is correct |
47 |
Correct |
1 ms |
332 KB |
Output is correct |
48 |
Correct |
1 ms |
332 KB |
Output is correct |
49 |
Correct |
0 ms |
332 KB |
Output is correct |
50 |
Correct |
1 ms |
332 KB |
Output is correct |
51 |
Correct |
0 ms |
336 KB |
Output is correct |
52 |
Correct |
1 ms |
336 KB |
Output is correct |
53 |
Correct |
0 ms |
336 KB |
Output is correct |
54 |
Correct |
0 ms |
336 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
118 ms |
65760 KB |
Output is correct |
2 |
Correct |
102 ms |
65764 KB |
Output is correct |
3 |
Correct |
102 ms |
65856 KB |
Output is correct |
4 |
Correct |
105 ms |
65764 KB |
Output is correct |
5 |
Correct |
109 ms |
65844 KB |
Output is correct |
6 |
Correct |
49 ms |
64832 KB |
Output is correct |
7 |
Correct |
146 ms |
73884 KB |
Output is correct |
8 |
Correct |
68 ms |
58488 KB |
Output is correct |
9 |
Correct |
103 ms |
61000 KB |
Output is correct |
10 |
Correct |
96 ms |
61128 KB |
Output is correct |
11 |
Correct |
54 ms |
55768 KB |
Output is correct |
12 |
Correct |
0 ms |
336 KB |
Output is correct |
13 |
Correct |
0 ms |
336 KB |
Output is correct |
14 |
Correct |
0 ms |
336 KB |
Output is correct |
15 |
Correct |
1 ms |
336 KB |
Output is correct |
16 |
Correct |
0 ms |
312 KB |
Output is correct |
17 |
Correct |
1 ms |
312 KB |
Output is correct |
18 |
Correct |
0 ms |
336 KB |
Output is correct |
19 |
Correct |
0 ms |
336 KB |
Output is correct |
20 |
Correct |
0 ms |
336 KB |
Output is correct |
21 |
Correct |
0 ms |
336 KB |
Output is correct |
22 |
Correct |
0 ms |
336 KB |
Output is correct |
23 |
Correct |
1 ms |
336 KB |
Output is correct |
24 |
Correct |
0 ms |
336 KB |
Output is correct |
25 |
Correct |
1 ms |
336 KB |
Output is correct |
26 |
Correct |
1 ms |
336 KB |
Output is correct |
27 |
Correct |
0 ms |
336 KB |
Output is correct |
28 |
Correct |
0 ms |
336 KB |
Output is correct |
29 |
Correct |
1 ms |
336 KB |
Output is correct |
30 |
Correct |
0 ms |
336 KB |
Output is correct |
31 |
Correct |
1 ms |
336 KB |
Output is correct |
32 |
Correct |
0 ms |
336 KB |
Output is correct |
33 |
Correct |
0 ms |
336 KB |
Output is correct |
34 |
Correct |
0 ms |
336 KB |
Output is correct |
35 |
Correct |
0 ms |
308 KB |
Output is correct |
36 |
Correct |
0 ms |
336 KB |
Output is correct |
37 |
Correct |
0 ms |
336 KB |
Output is correct |
38 |
Correct |
0 ms |
336 KB |
Output is correct |
39 |
Correct |
1 ms |
336 KB |
Output is correct |
40 |
Correct |
0 ms |
336 KB |
Output is correct |
41 |
Correct |
0 ms |
336 KB |
Output is correct |
42 |
Correct |
1 ms |
336 KB |
Output is correct |
43 |
Correct |
0 ms |
336 KB |
Output is correct |
44 |
Correct |
1 ms |
336 KB |
Output is correct |
45 |
Correct |
0 ms |
336 KB |
Output is correct |
46 |
Correct |
0 ms |
336 KB |
Output is correct |
47 |
Correct |
0 ms |
336 KB |
Output is correct |
48 |
Correct |
0 ms |
336 KB |
Output is correct |
49 |
Correct |
0 ms |
336 KB |
Output is correct |
50 |
Correct |
0 ms |
336 KB |
Output is correct |
51 |
Correct |
0 ms |
336 KB |
Output is correct |
52 |
Correct |
0 ms |
336 KB |
Output is correct |
53 |
Correct |
0 ms |
336 KB |
Output is correct |
54 |
Correct |
0 ms |
336 KB |
Output is correct |