Submission #1092816

#	Time	Username	Problem	Language	Result	Execution time	Memory
1092816		owoovo	Palindromic Partitions (CEOI17_palindromic)	C++17	100 / 100	433 ms	20776 KiB

palindromic

#include<bits/stdc++.h>
#define ll long long
#define F first 
#define S second 
using namespace std;
const ll p=1e9+7;
const ll c=47;
ll hah[1000010];
ll pw(ll a,ll b){
    ll ans=1;
    while(b){
        if(b&1)ans*=a,ans%=p;
        b>>=1;
        a*=a;
        a%=p;
    }
    return ans;
}
ll hh(int l,int r){
    return ((hah[r]-hah[l-1]*pw(c,r-l+1)%p)%p+p)%p;
}
int main(){
    ios::sync_with_stdio(0);
    cin.tie(0);
    int t;
    cin>>t;
    while(t--){
        string s;
        cin>>s;
        int n=s.size();
        for(int i=1;i<=n;i++){
            char ch=s[i-1];
            ll val=int(ch-'a')+3;
            hah[i]=hah[i-1]*c+val;
            hah[i]%=p;
        }
        int l=1,r=n,i=0,ans=0;
        while(l<=r){
            while(l+i<=r&&hh(l,l+i)!=hh(r-i,r)){
                i++;
            }
            ans+=2;
            if(l+i==r)ans--;
            l=l+i+1,r=r-i-1,i=0;
        }
        cout<<ans<<'\n';
    }
    return 0;
}

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