Submission #745042

#	Time	Username	Problem	Language	Result	Execution time	Memory
745042		zeta7532	Palindromes (APIO14_palindrome)	C++17	0 / 100	1071 ms	1288 KiB

palindrome

#include <bits/stdc++.h>
#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
using namespace std;
using ll = long long;
const ll mod = 998244353;
#define fi first
#define se second
#define rep(i,n) for(ll i=0;i<n;i++)
#define all(x) x.begin(),x.end()
#define faster ios::sync_with_stdio(false);cin.tie(nullptr)
 
int main() {
    string s;
    cin >> s;
    ll N=s.size();
    if(N>10000) return 0;
    vector<ll> A(N+1);
    A[0]=0;
    ll k=1;
    rep(i,N) A[i+1]=(A[i]+(s[i]-'a'+1)*k)%mod,k=k*100%mod;
    vector<ll> inv(N);
    inv[0]=1;
    rep(i,N-1) inv[i+1]=inv[i]*828542813%mod;
    unordered_map<ll,ll> M1,M2;
    ll ans=0;
    for(ll i=0;i<N;i++){
        for(ll j=0;j<min(i+1,N-i);j++){
            if(s[i-j]!=s[i+j]) break;
            ll x=(A[j+i+1]-A[i])*inv[i]%mod;
            M1[x]+=j*2+1;
            ans=max(ans,M1[x]);
        }
    }
    for(ll i=0;i<N-1;i++){
        for(ll j=0;j<min(i+1,N-1-i);j++){
            if(s[i-j]!=s[i+1+j]) break;
            ll x=(A[j+i+2]-A[i+1])*inv[i+1]%mod;
            M2[x]+=j*2+2;
            ans=max(ans,M2[x]);
        }
    }
    cout << ans << endl;
    return 0;
}    

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