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Submission #107577

# Submission time Handle Problem Language Result Execution time Memory
107577 2019-04-25T08:23:51 Z dfistric Three Friends (BOI14_friends) C++14
100 / 100
 191 ms 66980 KB 
#include <bits/stdc++.h>

#define FOR(i, a, b) for (int i = (a); i < (b); i++)
#define FORd(i, a, b) for (int i = (a); i >= (b); i--)
#define REP(i, n) FOR(i, 0, n)
#define ll long long

using namespace std;

const int MAXN = 2001000;
ll ha[MAXN], pot[MAXN];
ll ha2[MAXN], pot2[MAXN];
const int BASE = 35537;
const int MOD = 1e9 + 7;
const int BASE2 = 57737;
const int MOD2 = 1e9 + 9;

ll val(int x, int y) {
    if (y < x) return 0;

    ll out = ha[y];
    if (x) out = (((out - ha[x - 1] * pot[y - x + 1]) % MOD) + MOD) % MOD;
    return out;
}

ll val2(int x, int y) {
    if (y < x) return 0;

    ll out = ha2[y];
    if (x) out = (((out - ha2[x - 1] * pot2[y - x + 1]) % MOD2) + MOD2) % MOD2;
    return out;
}

int main() {
    ios_base::sync_with_stdio(false);
    pot[0] = 1;
    FOR(i, 1, MAXN) pot[i] = (pot[i - 1] * BASE) % MOD; 
    pot2[0] = 1;
    FOR(i, 1, MAXN) pot2[i] = (pot2[i - 1] * BASE2) % MOD2; 
 
    int n;
    cin >> n;
    string s;
    cin >> s;

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

    ll curr = 0, curr2 = 0;
    REP(i, n) {
        curr = (curr * BASE + s[i]) % MOD;
        ha[i] = curr;
        curr2 = (curr2 * BASE2 + s[i]) % MOD2;
        ha2[i] = curr2;
    }

    string out = "";
    ll V = -1, V2 = -1;
    REP(i, n) {
        if (i <= n / 2) {
            ll a = (val(0, i - 1) * pot[n / 2 - i] + val(i + 1, n / 2)) % MOD;
            ll b = val(n / 2 + 1, n - 1);
            ll a2 = (val2(0, i - 1) * pot2[n / 2 - i] + val2(i + 1, n / 2)) % MOD2;
            ll b2 = val2(n / 2 + 1, n - 1);

            if (a != b) continue;
            if (a2 != b2) continue;
            
            if (out != "" && (V != a || V2 != a2))  {
                cout << "NOT UNIQUE\n";
                return 0;
            } else if (out == "") {
                V = a;
                V2 = a2;
                out = s.substr(n / 2 + 1, n / 2);
            }
        } else {
            ll a = val(0, n / 2 - 1);
            ll b = (val(n / 2, i - 1) * pot[n - i - 1] + val(i + 1, n - 1)) % MOD;
            ll a2 = val2(0, n / 2 - 1);
            ll b2 = (val2(n / 2, i - 1) * pot2[n - i - 1] + val2(i + 1, n - 1)) % MOD2;

            if (a != b) continue;
            if (a2 != b2) continue;

            if (out != "" && (V != a || V2 != a2))  {
                cout << "NOT UNIQUE\n";
                return 0;
            } else if (out == "") {
                V = a;
                V2 = a2;
                out = s.substr(0, n / 2);
            }
        }
    }

    if (out == "") cout << "NOT POSSIBLE\n";
    else           cout << out << "\n";

    return 0;
}

Subtask #1
35.0 / 35.0

# Verdict Execution time Memory Grader output
1 Correct 48 ms 31608 KB Output is correct
2 Correct 44 ms 31608 KB Output is correct
3 Correct 46 ms 31736 KB Output is correct
4 Correct 50 ms 31628 KB Output is correct
5 Correct 48 ms 31608 KB Output is correct
6 Correct 47 ms 31608 KB Output is correct
7 Correct 49 ms 31736 KB Output is correct
8 Correct 47 ms 31736 KB Output is correct
9 Correct 44 ms 31736 KB Output is correct
10 Correct 49 ms 31608 KB Output is correct
11 Correct 45 ms 31608 KB Output is correct
12 Correct 47 ms 31608 KB Output is correct
13 Correct 48 ms 31736 KB Output is correct
14 Correct 48 ms 31608 KB Output is correct
15 Correct 48 ms 31608 KB Output is correct
16 Correct 46 ms 31736 KB Output is correct
17 Correct 62 ms 31608 KB Output is correct
18 Correct 46 ms 31640 KB Output is correct
19 Correct 49 ms 31864 KB Output is correct
20 Correct 48 ms 31736 KB Output is correct
21 Correct 47 ms 31736 KB Output is correct
22 Correct 47 ms 31736 KB Output is correct
23 Correct 47 ms 31736 KB Output is correct
24 Correct 44 ms 31608 KB Output is correct
25 Correct 51 ms 31736 KB Output is correct
26 Correct 45 ms 31608 KB Output is correct
27 Correct 49 ms 31736 KB Output is correct
28 Correct 46 ms 31608 KB Output is correct
29 Correct 46 ms 31736 KB Output is correct
30 Correct 48 ms 31736 KB Output is correct
31 Correct 46 ms 31608 KB Output is correct
32 Correct 129 ms 31608 KB Output is correct
33 Correct 50 ms 31648 KB Output is correct
34 Correct 48 ms 31708 KB Output is correct
35 Correct 57 ms 31740 KB Output is correct
36 Correct 48 ms 31636 KB Output is correct
37 Correct 46 ms 31736 KB Output is correct
38 Correct 45 ms 31744 KB Output is correct
39 Correct 45 ms 31608 KB Output is correct
40 Correct 46 ms 31708 KB Output is correct
41 Correct 71 ms 31736 KB Output is correct
42 Correct 47 ms 31736 KB Output is correct
43 Correct 50 ms 31708 KB Output is correct
44 Correct 51 ms 31736 KB Output is correct
45 Correct 48 ms 31716 KB Output is correct
46 Correct 55 ms 31864 KB Output is correct
47 Correct 50 ms 31736 KB Output is correct
48 Correct 49 ms 31736 KB Output is correct
49 Correct 47 ms 31608 KB Output is correct
50 Correct 47 ms 31736 KB Output is correct
51 Correct 51 ms 31736 KB Output is correct
52 Correct 48 ms 31736 KB Output is correct
53 Correct 46 ms 31736 KB Output is correct
54 Correct 46 ms 31736 KB Output is correct

Subtask #2
65.0 / 65.0

# Verdict Execution time Memory Grader output
1 Correct 147 ms 66968 KB Output is correct
2 Correct 170 ms 66936 KB Output is correct
3 Correct 139 ms 66884 KB Output is correct
4 Correct 153 ms 66844 KB Output is correct
5 Correct 150 ms 66920 KB Output is correct
6 Correct 51 ms 33820 KB Output is correct
7 Correct 191 ms 66980 KB Output is correct
8 Correct 137 ms 62488 KB Output is correct
9 Correct 137 ms 63344 KB Output is correct
10 Correct 137 ms 63484 KB Output is correct
11 Correct 127 ms 59640 KB Output is correct
12 Correct 46 ms 31708 KB Output is correct
13 Correct 56 ms 31608 KB Output is correct
14 Correct 47 ms 31736 KB Output is correct
15 Correct 46 ms 31608 KB Output is correct
16 Correct 47 ms 31608 KB Output is correct
17 Correct 47 ms 31688 KB Output is correct
18 Correct 45 ms 31736 KB Output is correct
19 Correct 46 ms 31736 KB Output is correct
20 Correct 49 ms 31736 KB Output is correct
21 Correct 47 ms 31608 KB Output is correct
22 Correct 47 ms 31608 KB Output is correct
23 Correct 54 ms 31608 KB Output is correct
24 Correct 47 ms 31864 KB Output is correct
25 Correct 48 ms 31608 KB Output is correct
26 Correct 45 ms 31736 KB Output is correct
27 Correct 48 ms 31736 KB Output is correct
28 Correct 45 ms 31608 KB Output is correct
29 Correct 46 ms 31736 KB Output is correct
30 Correct 46 ms 31608 KB Output is correct
31 Correct 47 ms 31628 KB Output is correct
32 Correct 50 ms 31736 KB Output is correct
33 Correct 46 ms 31608 KB Output is correct
34 Correct 47 ms 31736 KB Output is correct
35 Correct 47 ms 31636 KB Output is correct
36 Correct 50 ms 31736 KB Output is correct
37 Correct 46 ms 31608 KB Output is correct
38 Correct 45 ms 31736 KB Output is correct
39 Correct 45 ms 31608 KB Output is correct
40 Correct 45 ms 31736 KB Output is correct
41 Correct 45 ms 31736 KB Output is correct
42 Correct 51 ms 31740 KB Output is correct
43 Correct 47 ms 31736 KB Output is correct
44 Correct 48 ms 31724 KB Output is correct
45 Correct 46 ms 31692 KB Output is correct
46 Correct 50 ms 31608 KB Output is correct
47 Correct 45 ms 31656 KB Output is correct
48 Correct 47 ms 31736 KB Output is correct
49 Correct 46 ms 31608 KB Output is correct
50 Correct 45 ms 31636 KB Output is correct
51 Correct 50 ms 31608 KB Output is correct
52 Correct 45 ms 31608 KB Output is correct
53 Correct 49 ms 31736 KB Output is correct
54 Correct 46 ms 31736 KB Output is correct