oj.uz

Submission #394489

# Submission time Handle Problem Language Result Execution time Memory
394489 2021-04-26T17:50:45 Z ak2006 Three Friends (BOI14_friends) C++14
35 / 100
 500 ms 45304 KB 
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using vb = vector<bool>;
using vvb = vector<vb>;
using vi = vector<int>;
using vvi = vector<vi>;
using vl = vector<ll>;
using vvl = vector<vl>;
using vc = vector<char>;
using vvc = vector<vc>;
const ll mod = 1e9 + 7,inf = 1e18,p = 31;
#define pb push_back
#define fast ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
int n = 2e6 + 5;
vi a(n);
vl hsh(n,1),power(n,1);
ll poww(ll a,ll b)
{
    if (b == 0)return 1;
    if (b == 1)return a;
    ll ret = poww(a,b/2);
    if (b%2 == 0)return (ret * ret)%mod;
    return ((ret * ret)%mod * a)%mod;
}
ll inv(ll a)
{
    return (poww(a,mod - 2)%mod + mod)%mod;
}
ll get_hash(int a,int b)
{
    return (((hsh[b] - ((a >= 1 ? hsh[a - 1] : 0))%mod))%mod + mod)%mod;
}
int main()
{
    for (int i = 1;i<=n;i++)power[i] = (power[i - 1] * p)%mod;
    cin>>n;

    if (n % 2 == 0){cout<<"NOT POSSIBLE";return 0;}

    string s;
    cin>>s;

    for (int i = 0;i<n;i++)
        a[i] = s[i] - 'A' + 1;

    hsh[0] = a[0];
    set<int>vals;

    for (int i = 0;i<n - 1;i++)
        hsh[i + 1] = (poww(p,i + 1) * a[i + 1] + hsh[i])%mod;

    int cnt = 0,start = -1,len = (n - 1)/2;

    for (int i = 0;i<n;i++){
        if (i == 0){
            ll v1 = ((hsh[len] - hsh[0])%mod + mod)%mod;
            ll v2 = ((hsh[n - 1] - hsh[len])%mod + mod)%mod;
            if ((v1 * power[len])%mod == v2){
                vals.insert((v1 * inv(p))%mod);
                cnt++,start = 1;
            }
        }
        else if (i < len){
            ll v1 = ((((hsh[i - 1] * p)%mod + (hsh[len] - hsh[i]))%mod)%mod + mod)%mod;
            ll v2 = ((hsh[n - 1] - hsh[len])%mod + mod)%mod;
            if ((v1 * power[len])%mod == v2){
                vals.insert((v1 * inv(p))%mod);
                start = len + 1;
            }
        }
        else{
            ll v1 = hsh[len - 1];
            ll v2 = ((((hsh[i - 1] - hsh[len - 1]) * p)%mod + (hsh[n - 1] - hsh[i])%mod)%mod + mod)%mod;
            if ((v1 * power[len + 1])%mod == v2){
                vals.insert(v1);
                start = 0;
            }
        }
    }
    cnt = vals.size();
    if (cnt > 1)cout<<"NOT UNIQUE";
    else if (cnt == 0)cout<<"NOT POSSIBLE";
    else cout<<s.substr(start,len);
    return 0;
}

Subtask #1
35.0 / 35.0

# Verdict Execution time Memory Grader output
1 Correct 34 ms 39372 KB Output is correct
2 Correct 35 ms 39372 KB Output is correct
3 Correct 35 ms 39424 KB Output is correct
4 Correct 39 ms 39424 KB Output is correct
5 Correct 35 ms 39408 KB Output is correct
6 Correct 34 ms 39372 KB Output is correct
7 Correct 35 ms 39372 KB Output is correct
8 Correct 34 ms 39372 KB Output is correct
9 Correct 35 ms 39440 KB Output is correct
10 Correct 35 ms 39444 KB Output is correct
11 Correct 36 ms 39372 KB Output is correct
12 Correct 34 ms 39396 KB Output is correct
13 Correct 34 ms 39452 KB Output is correct
14 Correct 34 ms 39356 KB Output is correct
15 Correct 35 ms 39344 KB Output is correct
16 Correct 35 ms 39372 KB Output is correct
17 Correct 36 ms 39492 KB Output is correct
18 Correct 35 ms 39372 KB Output is correct
19 Correct 35 ms 39448 KB Output is correct
20 Correct 34 ms 39404 KB Output is correct
21 Correct 35 ms 39448 KB Output is correct
22 Correct 35 ms 39364 KB Output is correct
23 Correct 34 ms 39372 KB Output is correct
24 Correct 35 ms 39412 KB Output is correct
25 Correct 35 ms 39452 KB Output is correct
26 Correct 36 ms 39372 KB Output is correct
27 Correct 35 ms 39424 KB Output is correct
28 Correct 38 ms 39372 KB Output is correct
29 Correct 35 ms 39436 KB Output is correct
30 Correct 39 ms 39432 KB Output is correct
31 Correct 35 ms 39372 KB Output is correct
32 Correct 35 ms 39372 KB Output is correct
33 Correct 39 ms 39500 KB Output is correct
34 Correct 35 ms 39456 KB Output is correct
35 Correct 35 ms 39372 KB Output is correct
36 Correct 36 ms 39372 KB Output is correct
37 Correct 35 ms 39372 KB Output is correct
38 Correct 35 ms 39324 KB Output is correct
39 Correct 34 ms 39372 KB Output is correct
40 Correct 35 ms 39372 KB Output is correct
41 Correct 35 ms 39384 KB Output is correct
42 Correct 35 ms 39376 KB Output is correct
43 Correct 35 ms 39492 KB Output is correct
44 Correct 35 ms 39440 KB Output is correct
45 Correct 36 ms 39320 KB Output is correct
46 Correct 36 ms 39372 KB Output is correct
47 Correct 35 ms 39372 KB Output is correct
48 Correct 34 ms 39436 KB Output is correct
49 Correct 34 ms 39376 KB Output is correct
50 Correct 36 ms 39372 KB Output is correct
51 Correct 36 ms 39436 KB Output is correct
52 Correct 36 ms 39364 KB Output is correct
53 Correct 35 ms 39396 KB Output is correct
54 Correct 35 ms 39448 KB Output is correct

Subtask #2
0 / 65.0

# Verdict Execution time Memory Grader output
1 Correct 456 ms 43556 KB Output is correct
2 Correct 458 ms 43536 KB Output is correct
3 Correct 459 ms 43452 KB Output is correct
4 Correct 454 ms 43572 KB Output is correct
5 Correct 478 ms 43496 KB Output is correct
6 Correct 36 ms 39372 KB Output is correct
7 Execution timed out 763 ms 45304 KB Time limit exceeded
8 Halted 0 ms 0 KB -