Submission #339731

#	Time	Username	Problem	Language	Result	Execution time	Memory
339731		nandonathaniel	Palindromic Partitions (CEOI17_palindromic)	C++14	100 / 100	215 ms	45704 KiB

palindromic

#include<bits/stdc++.h>
using namespace std;
const int MAXN=1000005,MOD=1e9+7,inv=280000002;
 
int pref[MAXN],pkt[MAXN];
int dp[MAXN],N;
 
int get(int L,int R){
	if(L>R)return 0;
	return (pref[R]-((1LL*pref[L-1]*pkt[R-L+1])%MOD)+MOD)%MOD;
}

int DP(int L){
	int R=N+1-L;
	if(L>R)return 0;
	int &ret=dp[L];
	if(ret!=-1)return ret;
	ret=1;
	for(int i=1;i<=(R-L+1)/2;i++){
		if(get(L,L+i-1)==get(R-i+1,R)){
			ret=max(ret,2+DP(L+i));
			return ret;
		}
	}
	return ret;
}
 
int main(){
	ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
	int t;
	string s;
	cin >> t;
	while(t--){
		cin >> s;
		N=(int)s.length();
		pkt[0]=1;
		for(int i=0;i<N;i++){
			pref[i+1]=(26LL*pref[i]+s[i]-'a')%MOD;
			pkt[i+1]=(26LL*pkt[i])%MOD;
		}
		memset(dp,-1,sizeof(dp));
		cout << DP(1) << '\n';
	}
	return 0;
}

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