oj.uz

답안 #957527

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
957527 2024-04-04T01:17:05 Z YassirSalama 세 명의 친구들 (BOI14_friends) C++17
0 / 100
 500 ms 49280 KB 
#include <bits/stdc++.h>
using namespace std;
const int dx[4] = {1,0,-1,0}, dy[4] = {0,1,0,-1};
#define OVL(x,s) for(auto y:x) cout<<y<<s; cout<<"\n";
#ifdef IOI
void dbg_out() { cout << endl; }
template<typename Head, typename... Tail> void dbg_out(Head H, Tail... T) { cout << ' ' << H; dbg_out(T...); }
#define dbg(...) cout << "(" << #__VA_ARGS__ << "):", dbg_out(__VA_ARGS__);
#else
#define dbg(...) 1337;
#endif
#define endl "\n"
#define pb push_back
#define F first
#define S second
#define ll long long
#define md 1000000007
#define all(v) v.begin(),v.end()
const int MAXN=2000001+2;
const int MOD1=1e9+7,P=37;
// #define int long long
ll binpow(int a,int b,int mod){
	int res=1;
	while(b){
		if(b&1) res=((ll)res%mod*(ll)a%mod)%mod;
		a=((ll)a%mod*(ll)a%mod)%mod;
		b>>=1;
	}
	return res%mod;
}
ll invmod(int a,int mod){
	return (ll)binpow(a,mod-2,mod)%mod;
}
int pref1[MAXN];
ll inv1[MAXN];
const int MOD2=1404543827;
const int P2=83;
int pref2[MAXN];
ll inv2[MAXN];
int sum1(int l,int r){
	if(l==0) return (ll)pref1[r]%MOD1;
	else 
		return (((ll)pref1[r]-(ll)pref1[l-1]+3LL*MOD1)%MOD1*((ll)inv1[l]%MOD1))%MOD1;
}
int sum2(int l,int r){
	if(l==0) return (ll)pref2[r]%MOD2;
	else 
		return (((ll)pref2[r]-(ll)pref2[l-1]+3LL*MOD2)%MOD2*((ll)inv2[l]%MOD2))%MOD2;
}

signed main(){
ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
int n;
cin>>n;
string s;
cin>>s;
memset(pref1,0,sizeof(pref1));
if(n%2==0){
	cout<<"NOT POSSIBLE"<<endl;
	return 0;
}
inv1[0]=1;
inv1[1]=invmod(P,MOD1);
for(int i=2;i<MAXN;i++){
	inv1[i]=((ll)inv1[i-1]%MOD1*((ll)inv1[1]%MOD1))%MOD1;
}
ll c=1;
for(int i=0;i<n;i++){
	int x=s[i]-'A'+1;
	if(i) pref1[i]=pref1[i-1];
	pref1[i]%=MOD1;
	pref1[i]=(pref1[i]%MOD1+((ll)x%MOD1*(ll)c%MOD1)%MOD1)%MOD1;
	c=((ll)c%MOD1*P%MOD1)%MOD1;
}
inv2[0]=1;
inv2[1]=invmod(P2,MOD2);
for(int i=2;i<MAXN;i++){
	inv2[i]=(inv2[i-1]%MOD2*(inv2[1]%MOD2))%MOD2;
}
c=1;
for(int i=0;i<n;i++){
	int x=s[i]-'A'+1;
	if(i) pref2[i]=pref2[i-1];
	pref2[i]=(pref2[i]%MOD2+(x%MOD2*c%MOD2)%MOD2)%MOD2;
	c=(c%MOD2*P2%MOD2)%MOD2;
}
// for(int i=0;i<n;i++){
// 	dbg(pref1[i],pref2[i],inv1[i],inv2[i])
// }
vector<pair<int,int>> ans;
map<ll,pair<int,int>> mp;
for(int i=0;i<n;i++){
	int l1=0,r1=0,l2=0,r2=n-1;
	if(i==0){
		l1=1;
	}
	if(i==n-1){
		r2=n-2;
	}
	r1=l1+(n-2)/2;
	if(i>0&&i<=r1) r1++;
	l2=r2-(n-2)/2;
	if(i!=n-1&&i>=l2) l2--;
	if((i>r1&&i<l2)||i==0||i==n-1){
		if((ll)sum1(l1,r1)==(ll)sum1(l2,r2)&&(ll)sum2(l1,r1)==(ll)sum2(l2,r2)) {
			mp[sum1(l1,r1)]={l1,r1};
			ans.pb({l1,r1});
		}
		else continue;
	}
	if(i<=r1){
		int t=i-1;
		int t1=i+1;
		int s1=0;
		s1+=sum1(l1,t)%MOD1;
		s1%=MOD1;
		s1+=((ll)binpow(P,(i%((n-2)/2+1)),MOD1)%MOD1*sum1(t1,r1)%MOD1)%MOD1;
		s1%=MOD1;
		s1+=MOD1;
		s1%=MOD1;
		int s2=0;
		s2+=sum2(l1,t)%MOD2;
		s2%=MOD2;
		s2+=(binpow(P2,(i%((n-2)/2+1)),MOD2)%MOD2*sum2(t1,r1)%MOD2)%MOD2;
		s2%=MOD2;
		s2+=MOD2;
		s2%=MOD2;
		if(s1==sum1(l2,r2)%MOD1&&s2==sum2(l2,r2)%MOD2){
			ans.pb({l2,r2});
			mp[s1]={l2,r2};
		}
	}else{
		int t=i-1;
		int t1=i+1;
		int s1=0;
		s1+=sum1(l2,t)%MOD1;
		s1%=MOD1;
		s1+=(binpow(P,(i%((n-2)/2+1)),MOD1)%MOD1*sum1(t1,r2)%MOD1)%MOD1;
		s1%=MOD1;
		s1+=MOD1;
		s1%=MOD1;
		int s2=0;
		s2+=sum2(l2,t)%MOD2;
		s2%=MOD2;
		s2+=(binpow(P2,(i%((n-2)/2+1)),MOD2)%MOD2*sum2(t1,r2)%MOD2)%MOD2;
		s2%=MOD2;
		s2+=MOD2;
		s2%=MOD2;
		// dbg(i,s1,s2,sum1(l1,r1),sum2(l1,r1))
		// dbg(s2,sum2(l1,r1))
		if(s1==sum1(l1,r1)&&s2==sum2(l1,r1)%MOD2) {
			ans.pb({l1,r1});
			mp[s1]={l1,r1};
		}
	}
}
// dbg("done")
if(mp.size()==1){
	pair<int,int> anss=mp.begin()->second;
	cout<<s.substr(anss.F,anss.S-anss.F+1)<<endl;
}else{
	if(mp.empty()){
		cout<<"NOT POSSIBLE"<<endl;
		return 0;
	}
	cout<<"NOT UNIQUE"<<endl;
	return 0;
}

}

Subtask #1
0 / 35.0

# 결과 실행 시간 메모리 Grader output
1 Correct 32 ms 41044 KB Output is correct
2 Correct 23 ms 41052 KB Output is correct
3 Correct 23 ms 41048 KB Output is correct
4 Correct 22 ms 41048 KB Output is correct
5 Correct 24 ms 40992 KB Output is correct
6 Correct 22 ms 41044 KB Output is correct
7 Correct 22 ms 40996 KB Output is correct
8 Correct 22 ms 41052 KB Output is correct
9 Correct 24 ms 41052 KB Output is correct
10 Correct 24 ms 41048 KB Output is correct
11 Correct 22 ms 41304 KB Output is correct
12 Correct 22 ms 41044 KB Output is correct
13 Correct 22 ms 41044 KB Output is correct
14 Correct 22 ms 41052 KB Output is correct
15 Correct 22 ms 40988 KB Output is correct
16 Correct 22 ms 41044 KB Output is correct
17 Correct 22 ms 41040 KB Output is correct
18 Correct 23 ms 41044 KB Output is correct
19 Correct 22 ms 41052 KB Output is correct
20 Correct 22 ms 41052 KB Output is correct
21 Correct 22 ms 41052 KB Output is correct
22 Correct 22 ms 41048 KB Output is correct
23 Correct 23 ms 41040 KB Output is correct
24 Correct 2 ms 10072 KB Output is correct
25 Correct 2 ms 10332 KB Output is correct
26 Correct 3 ms 10188 KB Output is correct
27 Correct 22 ms 41040 KB Output is correct
28 Correct 22 ms 41232 KB Output is correct
29 Correct 22 ms 41064 KB Output is correct
30 Correct 23 ms 41300 KB Output is correct
31 Correct 22 ms 41060 KB Output is correct
32 Correct 22 ms 41248 KB Output is correct
33 Correct 22 ms 41256 KB Output is correct
34 Correct 22 ms 41044 KB Output is correct
35 Correct 22 ms 41052 KB Output is correct
36 Correct 22 ms 41040 KB Output is correct
37 Correct 22 ms 41052 KB Output is correct
38 Correct 22 ms 41248 KB Output is correct
39 Correct 22 ms 41052 KB Output is correct
40 Correct 22 ms 41040 KB Output is correct
41 Correct 22 ms 41052 KB Output is correct
42 Correct 22 ms 41044 KB Output is correct
43 Correct 22 ms 41052 KB Output is correct
44 Incorrect 22 ms 41052 KB Output isn't correct
45 Halted 0 ms 0 KB -

Subtask #2
0 / 65.0

# 결과 실행 시간 메모리 Grader output
1 Execution timed out 808 ms 49280 KB Time limit exceeded
2 Halted 0 ms 0 KB -