Submission #934230

#	Time	Username	Problem	Language	Result	Execution time	Memory
934230		Faisal_Saqib	Palindromic Partitions (CEOI17_palindromic)	C++17	100 / 100	296 ms	27064 KiB

palindromic

#include <iostream>
using namespace std;
#define int long long
#define ll long long
const ll base=717;
const ll mod=1e9+9;
const int N=1e6+100;
ll n,pre[N],pw[N];

void Hash(string& s)
{
    n=(int)s.size();
    pre[0]=0;
    for(int i=1;i<=n;i++)
    {
    	pre[i]=(pre[i-1]*base)%mod;
    	pre[i]+=(s[i-1]-'a');
    	pre[i]%=mod;
    }
    pw[0]=1;
    for(int i=1;i<=n;i++)
        pw[i]=(pw[i-1]*base)%mod;
}
// (l,r)
// s[r]
// s[l]*(r-l) + .. s[r]
// s[l-1]
// s[l-1]
int get(int l,int r)//inclusive 1-based indexing
{
	return (pre[r]+mod-((pre[l-1]*pw[r-l+1])%mod))%mod;
}
void solve()
{
	string s;
	cin>>s;
	Hash(s);
	int l=0;
	int r=n+1;
	int cnt=0;
	while((l+1)<r)
	{
		int sl=l;
		int sr=r;
		for(int len=1;len<=(r-l-1);len++)	
		{
			if(get(l+1,l+len)==get(r-len,r-1))
			{
				cnt++;
				cnt+=((l+1!=(r-len)) or ((l+len)!=(r-1)));
				l+=len;
				r-=len;
				break;
			}
		}
	}
	cout<<cnt<<endl;
	// both endpoints are exclusive	(l,r)
}
signed main()
{
	int t;
	cin>>t;
	while(t--)
	{
		solve();
	}
}

Compilation message (stderr)

palindromic.cpp: In function 'void solve()':
palindromic.cpp:43:7: warning: unused variable 'sl' [-Wunused-variable]
   43 |   int sl=l;
      |       ^~
palindromic.cpp:44:7: warning: unused variable 'sr' [-Wunused-variable]
   44 |   int sr=r;
      |       ^~

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