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답안 #541674

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
541674 2022-03-24T07:02:06 Z Aldas25 회문 (APIO14_palindrome) C++14
23 / 100
 1000 ms 43244 KB 
#include <bits/stdc++.h>

using namespace std;

#define FAST_IO ios_base::sync_with_stdio(0); cin.tie(nullptr)
#define FOR(i, a, b) for (int i = (a); i <= (b); i++)
#define REP(n) FOR(O, 1, (n))
#define f first
#define s second
#define pb push_back
typedef long long ll;
typedef vector<int> vi;
typedef pair<int, int> pii;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

const int MAXN = 300100;
//const ll MOD1 = 1e9+7;
//const ll MOD2 = rng() % ((ll)1e7) + ((ll)1e8);

ll pwr (ll a, ll p, ll m) {
    if (p == 0) return 1ll;
    if (p == 1) return a%m;
    ll ret = pwr(a, p/2, m);
    ret = (ret*ret) % m;
    if (p % 2 == 1) ret *= a%m;
    return ret%m;
}
ll modInv (ll a, ll m) {
    return pwr(a%m, m-2, m);
}

struct stringHash {
    ll pw[MAXN];
    ll pwInv[MAXN];
    ll MOD;
    ll pref[MAXN];
    ll suf[MAXN];
    int n;

    void build (ll _MOD, string s, int _n) {
        MOD = _MOD;
        n = _n;

        pw[0] = 1;
        FOR(i, 1, n+1) pw[i] = (pw[i-1] * 26) % MOD;
        FOR(i, 0, n+1) pwInv[i] = modInv(pw[i], MOD);

        pref[0] = 0;
        FOR(i, 1, n) {
            pref[i] = (pref[i-1] * 26) % MOD;
            pref[i] = (pref[i] + (s[i-1]-'a')) % MOD;
        }

        suf[n+1] = 0;
        for (int i = n; i > 0; i--) {
            suf[i] = (suf[i+1] * 26) % MOD;
            suf[i] = (suf[i] + (s[i-1]-'a')) % MOD;
        }
    }

    ll prefHsh (int i, int j) {
        ll ret = pref[j] - ((pw[j-i+1] * pref[i-1])%MOD) + MOD;
        ret %= MOD;
        //ret = (ret * pwInv[j-1]) % MOD;
        //ret = (ret * pw[n-i]) % MOD;
        return ret;
    }

    ll sufHsh (int i, int j) {
        ll ret = suf[i] - ((pw[j-i+1] * suf[j+1])%MOD) + MOD;
        ret %= MOD;
        //cout << "  suf m = " << MOD << " i = " << i << " j = " << j << "  676 / 26*26 = " << ((676) * pwInv[2])%MOD << endl;
        //cout << "     suf[i] = " << suf[i] << "   ret = " << ret << endl;
        //ret = (ret * pwInv[n-i]) % MOD;
        //ret = (ret * pw[j-1]) % MOD;
        return ret;
    }

    bool pal (int i, int j) {
        return prefHsh(i, j) == sufHsh(i, j);
    }
};

int n;
string s;
stringHash h1, h2;
map<pair<ll,pair<ll, ll>>, ll> cnt;

int main()
{
    FAST_IO;

    ll m1 = 1e9+7;
    ll m2 = rng() % ((ll)1e7) + ((ll)1e8);

    cin >> s;
    n = s.length();

    h1.build (m1, s, n);
    h2.build (m2, s, n);

    FOR(i, 1, n) FOR(j, i, n) {
        //cout << " i = " << i << " j = " << j << " pal1 = " << h1.pal(i, j) << " pal2 = " << h2.pal(i, j) << endl;
        //cout << "   pref1 = " << h1.prefHsh(i, j) << " suf1 = " << h1.sufHsh(i, j) << endl;

        if (h1.pal(i, j) && h2.pal(i, j)) {
            cnt[{j-i+1, {h1.prefHsh(i, j), h2.prefHsh(i, j)}}]++;
        }
    }

    ll ans = 0;
    for (auto p : cnt) {
        ll len = p.f.f;
        ll c = p.s;
        ans = max(ans, len*c);
    }

    cout << ans << "\n";

    return 0;
}

Subtask #1
8.0 / 8.0

# 결과 실행 시간 메모리 Grader output
1 Correct 1 ms 340 KB Output is correct
2 Correct 1 ms 340 KB Output is correct
3 Correct 1 ms 340 KB Output is correct
4 Correct 0 ms 340 KB Output is correct
5 Correct 0 ms 340 KB Output is correct
6 Correct 0 ms 340 KB Output is correct
7 Correct 1 ms 344 KB Output is correct
8 Correct 1 ms 340 KB Output is correct
9 Correct 1 ms 340 KB Output is correct
10 Correct 1 ms 344 KB Output is correct
11 Correct 0 ms 340 KB Output is correct
12 Correct 0 ms 340 KB Output is correct
13 Correct 1 ms 340 KB Output is correct
14 Correct 1 ms 340 KB Output is correct
15 Correct 1 ms 340 KB Output is correct
16 Correct 1 ms 340 KB Output is correct
17 Correct 1 ms 340 KB Output is correct
18 Correct 1 ms 340 KB Output is correct
19 Correct 1 ms 340 KB Output is correct
20 Correct 1 ms 336 KB Output is correct
21 Correct 1 ms 340 KB Output is correct
22 Correct 1 ms 340 KB Output is correct
23 Correct 1 ms 340 KB Output is correct
24 Correct 1 ms 340 KB Output is correct
25 Correct 1 ms 340 KB Output is correct
26 Correct 1 ms 336 KB Output is correct
27 Correct 1 ms 340 KB Output is correct
28 Correct 1 ms 340 KB Output is correct
29 Correct 1 ms 344 KB Output is correct
30 Correct 1 ms 340 KB Output is correct
31 Correct 1 ms 340 KB Output is correct
32 Correct 1 ms 340 KB Output is correct

Subtask #2
15.0 / 15.0

# 결과 실행 시간 메모리 Grader output
1 Correct 22 ms 468 KB Output is correct
2 Correct 19 ms 468 KB Output is correct
3 Correct 30 ms 468 KB Output is correct
4 Correct 17 ms 596 KB Output is correct
5 Correct 29 ms 468 KB Output is correct
6 Correct 30 ms 468 KB Output is correct
7 Correct 16 ms 468 KB Output is correct
8 Correct 22 ms 468 KB Output is correct
9 Correct 16 ms 472 KB Output is correct
10 Correct 16 ms 340 KB Output is correct
11 Correct 16 ms 468 KB Output is correct
12 Correct 17 ms 500 KB Output is correct

Subtask #3
0 / 24.0

# 결과 실행 시간 메모리 Grader output
1 Execution timed out 1079 ms 1756 KB Time limit exceeded
2 Halted 0 ms 0 KB -

Subtask #4
0 / 26.0

# 결과 실행 시간 메모리 Grader output
1 Execution timed out 1094 ms 14632 KB Time limit exceeded
2 Halted 0 ms 0 KB -

Subtask #5
0 / 27.0

# 결과 실행 시간 메모리 Grader output
1 Execution timed out 1087 ms 43244 KB Time limit exceeded
2 Halted 0 ms 0 KB -