oj.uz

Submission #481259

# Submission time Handle Problem Language Result Execution time Memory
481259 2021-10-20T07:26:10 Z tranxuanbach Three Friends (BOI14_friends) C++17
100 / 100
 164 ms 21136 KB 
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;

#define endl '\n'
#define fi first
#define se second
#define For(i, l, r) for (int i = l; i < r; i++)
#define ForE(i, l, r) for (int i = l; i <= r; i++)
#define FordE(i, l, r) for (int i = l; i >= r; i--)
#define Fora(v, a) for (auto v: a)
#define bend(a) a.begin(), a.end()
#define isz(a) ((signed)a.size())

using ll = long long;
using ld = long double;
using pii = pair <int, int>;
using vi = vector <int>;
using vpii = vector <pii>;
using vvi = vector <vi>;

mt19937 rando(chrono::steady_clock::now().time_since_epoch().count());
int randt(int l, int r){
    return rando() % (r - l + 1) + l;
}

const int N = 2e6 + 5;
int base, mod;

inline void sadd(int& x, int y){
    if ((x += y) >= mod) x -= mod;
    return;
}

inline int add(int x, int y){
    if ((x += y) >= mod) x -= mod;
    return x;
}

inline void ssub(int& x, int y){
    if ((x -= y) < 0) x += mod;
    return;
}

inline int sub(int x, int y){
    if ((x -= y) < 0) x += mod;
    return x;
}

inline int mul(int x, int y){
    return 1ll * x * y % mod;
}

inline int binpow(int x, int y){
    int ans = 1;
    while (y){
        if (y & 1) ans = mul(ans, x);
        x = mul(x, x);
        y >>= 1;
    }
    return ans;
}

inline int inv(int x){
    return binpow(x, mod - 2);
}

#define div __div__
inline int div(int x, int y){
    return mul(x, binpow(y, mod - 2));
}

int fac[N], invfac[N];

void calfac(){
    fac[0] = invfac[0] = 1;
    For(i, 1, N){
        fac[i] = mul(fac[i - 1], i);
    }
    invfac[N - 1] = binpow(fac[N - 1], mod - 2);
    FordE(i, N - 2, 1){
        invfac[i] = mul(invfac[i + 1], i + 1);
    }
}

inline int C(int n, int k){
    if (n < 0 or k < 0 or k > n){
        return 0;
    }
    return mul(fac[n], mul(invfac[k], invfac[n - k]));
}

inline int P(int n, int k){
    if (n < 0 or k < 0 or k > n){
        return 0;
    }
    return mul(fac[n], invfac[n - k]);
}

bool isprime(int x){
    if (x <= 1){
        return 0;
    }
    if (x <= 3){
        return 1;
    }
    if (x % 2 == 0 or x % 3 == 0){
        return 0;
    }
    for (int i = 5; i * i <= x; i += 6){
        if (x % i == 0 or x % (i + 2) == 0){
            return 0;
        }
    }
    return 1;
}

int n;
string s;

#define hash __hash__

int powbase[N];
int hash[N];

int calhash(int l, int r){
    return sub(hash[r], mul(hash[l - 1], powbase[r - l + 1]));
}

int ans = -1, idxans = -1;

signed main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    // freopen("KEK.inp", "r", stdin);
    // freopen("KEK.out", "w", stdout);
    cin >> n;
    cin >> s; s = ' ' + s;
    if (n % 2 == 0){
        cout << "NOT POSSIBLE" << endl;
        return 0;
    }

    base = randt(1000, 100000);
    while (!isprime(base)){
        base++;
    }
    mod = randt(500000000, 1000000000);
    while (!isprime(mod)){
        mod++;
    }
    powbase[0] = 1;
    For(i, 1, N){
        powbase[i] = mul(powbase[i - 1], base);
    }
    ForE(i, 1, n){
        hash[i] = add(mul(hash[i - 1], base), s[i] - 'A' + 1);
    }
    int mid = n / 2 + 1;
    ForE(i, 1, n){
        if (i == mid){
            if (calhash(1, mid - 1) == calhash(mid + 1, n)){
                if (ans == -1){
                    ans = calhash(1, mid - 1);
                    idxans = i;
                }
                else if (ans != calhash(1, mid - 1)){
                    cout << "NOT UNIQUE" << endl;
                    return 0;
                }
            }
            continue;
        }
        if (i < mid){
            int val = add(mul(calhash(1, i - 1), powbase[mid - i]), calhash(i + 1, mid));
            if (val == calhash(mid + 1, n)){
                if (ans == -1){
                    ans = val;
                    idxans = i;
                }
                else if (ans != val){
                    cout << "NOT UNIQUE" << endl;
                    return 0;
                }
            }
        }
        else{
            int val = add(mul(calhash(mid, i - 1), powbase[n - i]), calhash(i + 1, n));
            if (val == calhash(1, mid - 1)){
                if (ans == -1){
                    ans = val;
                    idxans = i;
                }
                else if (ans != val){
                    cout << "NOT UNIQUE" << endl;
                    return 0;
                }
            }
        }
    }
    if (ans == -1){
        cout << "NOT POSSIBLE" << endl;
        return 0;
    }
    if (idxans <= mid){
        ForE(i, mid + 1, n){
            cout << s[i];
        } cout << endl;
    }
    else{
        ForE(i, 1, mid - 1){
            cout << s[i];
        } cout << endl;
    }
}

/*
==================================================+
INPUT:                                            |
--------------------------------------------------|

--------------------------------------------------|
==================================================+
OUTPUT:                                           |
--------------------------------------------------|

--------------------------------------------------|
==================================================+
*/

Subtask #1
35.0 / 35.0

# Verdict Execution time Memory Grader output
1 Correct 26 ms 8136 KB Output is correct
2 Correct 26 ms 8128 KB Output is correct
3 Correct 27 ms 8136 KB Output is correct
4 Correct 28 ms 8132 KB Output is correct
5 Correct 26 ms 8140 KB Output is correct
6 Correct 26 ms 8132 KB Output is correct
7 Correct 27 ms 8140 KB Output is correct
8 Correct 26 ms 8140 KB Output is correct
9 Correct 25 ms 8140 KB Output is correct
10 Correct 27 ms 8132 KB Output is correct
11 Correct 26 ms 8028 KB Output is correct
12 Correct 29 ms 8140 KB Output is correct
13 Correct 27 ms 8140 KB Output is correct
14 Correct 29 ms 8060 KB Output is correct
15 Correct 27 ms 8132 KB Output is correct
16 Correct 26 ms 8140 KB Output is correct
17 Correct 26 ms 8112 KB Output is correct
18 Correct 26 ms 8132 KB Output is correct
19 Correct 28 ms 8116 KB Output is correct
20 Correct 28 ms 8072 KB Output is correct
21 Correct 29 ms 8048 KB Output is correct
22 Correct 30 ms 8028 KB Output is correct
23 Correct 26 ms 8140 KB Output is correct
24 Correct 0 ms 332 KB Output is correct
25 Correct 1 ms 332 KB Output is correct
26 Correct 1 ms 332 KB Output is correct
27 Correct 25 ms 8056 KB Output is correct
28 Correct 26 ms 8132 KB Output is correct
29 Correct 28 ms 8032 KB Output is correct
30 Correct 26 ms 8132 KB Output is correct
31 Correct 25 ms 8124 KB Output is correct
32 Correct 25 ms 8140 KB Output is correct
33 Correct 26 ms 8080 KB Output is correct
34 Correct 26 ms 8136 KB Output is correct
35 Correct 26 ms 8104 KB Output is correct
36 Correct 27 ms 8024 KB Output is correct
37 Correct 26 ms 8144 KB Output is correct
38 Correct 27 ms 8076 KB Output is correct
39 Correct 27 ms 8132 KB Output is correct
40 Correct 26 ms 8116 KB Output is correct
41 Correct 27 ms 8132 KB Output is correct
42 Correct 27 ms 8084 KB Output is correct
43 Correct 27 ms 8132 KB Output is correct
44 Correct 26 ms 8152 KB Output is correct
45 Correct 27 ms 8064 KB Output is correct
46 Correct 27 ms 8136 KB Output is correct
47 Correct 26 ms 8068 KB Output is correct
48 Correct 26 ms 8116 KB Output is correct
49 Correct 1 ms 332 KB Output is correct
50 Correct 25 ms 8072 KB Output is correct
51 Correct 26 ms 8132 KB Output is correct
52 Correct 26 ms 8180 KB Output is correct
53 Correct 27 ms 8140 KB Output is correct
54 Correct 27 ms 8140 KB Output is correct

Subtask #2
65.0 / 65.0

# Verdict Execution time Memory Grader output
1 Correct 152 ms 20908 KB Output is correct
2 Correct 158 ms 21008 KB Output is correct
3 Correct 157 ms 20924 KB Output is correct
4 Correct 157 ms 20916 KB Output is correct
5 Correct 164 ms 21136 KB Output is correct
6 Correct 6 ms 6320 KB Output is correct
7 Correct 157 ms 20944 KB Output is correct
8 Correct 125 ms 18816 KB Output is correct
9 Correct 144 ms 19680 KB Output is correct
10 Correct 151 ms 19712 KB Output is correct
11 Correct 117 ms 18040 KB Output is correct
12 Correct 27 ms 8132 KB Output is correct
13 Correct 26 ms 8140 KB Output is correct
14 Correct 25 ms 8024 KB Output is correct
15 Correct 24 ms 8136 KB Output is correct
16 Correct 27 ms 8140 KB Output is correct
17 Correct 26 ms 8140 KB Output is correct
18 Correct 26 ms 8096 KB Output is correct
19 Correct 27 ms 8140 KB Output is correct
20 Correct 26 ms 8140 KB Output is correct
21 Correct 26 ms 8140 KB Output is correct
22 Correct 26 ms 8132 KB Output is correct
23 Correct 26 ms 8132 KB Output is correct
24 Correct 26 ms 8120 KB Output is correct
25 Correct 25 ms 8068 KB Output is correct
26 Correct 26 ms 8036 KB Output is correct
27 Correct 26 ms 8144 KB Output is correct
28 Correct 27 ms 8088 KB Output is correct
29 Correct 27 ms 8132 KB Output is correct
30 Correct 27 ms 8140 KB Output is correct
31 Correct 25 ms 8084 KB Output is correct
32 Correct 24 ms 8140 KB Output is correct
33 Correct 26 ms 8132 KB Output is correct
34 Correct 26 ms 8140 KB Output is correct
35 Correct 1 ms 332 KB Output is correct
36 Correct 1 ms 332 KB Output is correct
37 Correct 1 ms 332 KB Output is correct
38 Correct 25 ms 8148 KB Output is correct
39 Correct 26 ms 8048 KB Output is correct
40 Correct 25 ms 8136 KB Output is correct
41 Correct 26 ms 8072 KB Output is correct
42 Correct 28 ms 8176 KB Output is correct
43 Correct 26 ms 8096 KB Output is correct
44 Correct 27 ms 8132 KB Output is correct
45 Correct 27 ms 8132 KB Output is correct
46 Correct 24 ms 8140 KB Output is correct
47 Correct 26 ms 8144 KB Output is correct
48 Correct 26 ms 8132 KB Output is correct
49 Correct 27 ms 8036 KB Output is correct
50 Correct 26 ms 8052 KB Output is correct
51 Correct 26 ms 8132 KB Output is correct
52 Correct 25 ms 8064 KB Output is correct
53 Correct 26 ms 8128 KB Output is correct
54 Correct 26 ms 8148 KB Output is correct