Submission #406571

#	Time	Username	Problem	Language	Result	Execution time	Memory
406571		Pichon5	Palindromic Partitions (CEOI17_palindromic)	C++17	100 / 100	339 ms	26808 KiB

palindromic

#include<bits/stdc++.h>
#define lcm(a,b) (a/__gcd(a,b))*b
#define fast ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define ll long long int
#define vi vector<int>
#define vll vector<ll>
#define pb push_back
#define F first
#define S second

//"\n"
//algoritmo para calcular la cantidad de substrings diferentes
using namespace std;
const ll MOD=1e9+9;
const ll p=131;
const int N=1e6+5;
ll P[N];
ll h[N];
int main()
{
    //freopen("palindromic.0.02.in","r",stdin);
    int t;
    string s;
    cin>>t;
    while(t--){
        cin>>s;
        ll n=s.size();
        h[0]=0;
        ll pot=1;
        for(int i=0;i<n;i++){
            ll x=s[i]-'a'+1;
            P[i]=pot;
            h[i+1]=(h[i]+x*pot)%MOD;
            pot=(pot*p)%MOD;
        }
        int tam=1;
        int izq=0,der=n-1;
        int res=0;
        while(1){
            if(izq+tam-1>=der-tam+1){
                res++;
                break;
            }
            ll a=(h[izq+tam]-h[izq]+MOD)%MOD;
            a=(a*P[n-izq-1])%MOD;
            ll b=(h[der+1]-h[der-tam+1]+MOD)%MOD;
            b=(b*P[(n-1)-(der-tam+1)])%MOD;
            if(a==b){
                if(izq+tam==der-tam+1){
                    res+=2;
                    break;
                }
                izq+=tam;
                der-=tam;
                tam=1;
                res+=2;
            }else{
                tam++;
            }

        }
        cout<<res<<endl;
    }

    return 0;
}
//https://codeforces.com/contest/911/problem/D
//https://onlinejudge.org/index.php?option=onlinejudge&page=show_problem&problem=1021
//freopen("palindromic.3.00.in","r",stdin);

• Subtask 1: 15 / 15
• Subtask 2: 20 / 20
• Subtask 3: 25 / 25
• Subtask 4: 40 / 40