Submission #390056

#	Time	Username	Problem	Language	Result	Execution time	Memory
390056		vonatlus	Palindromes (APIO14_palindrome)	C++14	23 / 100	1093 ms	19904 KiB

palindrome

/// adil sultanov | vonat1us 

#pragma GCC optimize("O3")
//#pragma comment(linker, "/STACK:36777216")

#include<bits/stdc++.h>

#define x first
#define y second
#define pb push_back
#define sz(x) (int) x.size()
#define all(z) (z).begin(), (z).end()
 
using namespace std;

using ll = long long;
using pii = pair<int, int>;                                   

const int MOD = 1e9 + 7; 
const int INF = 1e9 + 1e2;
  
void fin() {
#ifdef AM
    freopen(".in", "r", stdin);
#endif        
}                   

const bool flag = 0;

const int N = 1e5+10;
const int p = 31;

ll h[N], hr[N], po[N];

int mult(int a, int b) {
    return a*1ll*b % MOD;
}

void ma1n() {
    string s;
    cin >> s;
    int n = sz(s);
    po[0] = 1;
    for (int i = 1; i <= n; ++i) {
        po[i] = mult(po[i-1], p);
    }
    for (int i = 0; i < n; ++i) {
        h[i+1] = (h[i]*p + s[i]) % MOD;
    }
    reverse(all(s));
    for (int i = 0; i < n; ++i) {
        hr[i+1] = (hr[i]*p + s[i]) % MOD;
    }
    auto get = [&](int l, int r, int t) {
        if (t) {
            r = n-r+1;
            l = n-l+1;
            swap(l, r);
            return (hr[r] - mult(hr[l-1], po[r-l+1]) + MOD) %MOD;
        } else {
            return (h[r] - mult(h[l-1], po[r-l+1]) + MOD) %MOD;
        }
    };
    unordered_map<int, int> cnt;
    for (int i = 1; i <= n; ++i) {
        for (int j = i; j <= n; ++j) {
            cnt[get(i, j, 0)]++;
        }
    }            
    ll ans = 0;
    for (int i = 1; i <= n; ++i) {
        for (int j = i; j <= n; ++j) {
            if (get(i, j, 0) == get(i, j, 1)) {
                ans = max(ans, cnt[get(i, j, 0)] * 1ll * (j-i+1));
            }   
        }
    }
    cout << ans;
} 

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(nullptr), fin();
    int ts = 1;
    if (flag) {
        cin >> ts;
    }
    while (ts--) {
        ma1n(); 
    }
    return 0;
}

• Subtask 1: 8 / 8
• Subtask 2: 15 / 15
• Subtask 3: 0 / 24
• Subtask 4: 0 / 26
• Subtask 5: 0 / 27