Submission #900043

#	Time	Username	Problem	Language	Result	Execution time	Memory
900043		1075508020060209tc	Palindromes (APIO14_palindrome)	C++14	0 / 100	1045 ms	28100 KiB

palindrome

#pragma GCC optimize("O3")
#include<bits/stdc++.h>
using namespace std;
#define int long long
#define X first
#define Y second
#define SZ(x) (int)(x).size()
const int mod=1e9+7;
int qpow(int x,int t){
if(t==0){return 1;}
if(t%2==1){return qpow(x,t-1)*x%mod;}
int xx=qpow(x,t/2);
return xx*xx%mod;
}
int tme[500005];
struct rlhsh{
vector<int>hsh;
int n;
void init(string s){
n=s.size();
hsh.resize(s.size()+10,0);
for(int i=1;i<=n;i++){
    hsh[i]=(hsh[i-1]+(s[i-1]-'a')*tme[i])%mod;
}
}
int gthsh(int l,int r){
int ret=(hsh[r]-hsh[l-1]+mod)*qpow(tme[l-1],mod-2)%mod;
return ret;
}
};




int n;

pair<int,int>rev(int l,int r){
l=n-l+1;r=n-r+1;
swap(l,r);
return {l,r};
}

string s;

signed main(){
tme[0]=1;
for(int i=1;i<=500000;i++){
    tme[i]=tme[i-1]*37%mod;
}


cin>>s;
n=s.size();
rlhsh sh;
sh.init(s);
reverse(s.begin(),s.end());
rlhsh rsh;
rsh.init(s);
int ans=1;
map<int,int>mp;
for(int i=1;i<=n;i++){
    for(int j=i;j<=n;j++){
        int v=sh.gthsh(i,j);
        if(v==rsh.gthsh(n-j+1,n-i+1)){
            mp[v]++;
            ans=max(ans,mp[v]*(j-i+1));
        }
    }
}
cout<<ans<<"\n";

}

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