Submission #146834

#	Time	Username	Problem	Language	Result	Execution time	Memory
146834		MvC	Palindromes (APIO14_palindrome)	C++14	23 / 100	1046 ms	27188 KiB

palindrome

#pragma GCC target("avx2")
#pragma GCC optimization("O3")
#pragma GCC optimization("unroll-loops")
#include<bits/stdc++.h>
//#include "boxes.h"
#define rc(x) return cout<<x<<endl,0
#define pb push_back
#define mkp make_pair
#define in insert
#define er erase
#define fd find
#define fr first
#define sc second
typedef long long ll;
typedef long double ld;
const ll INF=0x3f3f3f3f3f3f3f3f;
const ll llinf=(1LL<<61);
const int inf=(1<<30);
const int nmax=1e4+50;
const ll mod=1e9+7;
const ll p=31;
using namespace std;
int n,i,rs,x,r,l;
bitset<nmax>b[nmax];
string s;
char c[nmax];
ll pw[nmax],in;
map<int,int>mp;
void ad(int &x,int y)
{
	x+=y;
	if(x>=mod)x-=mod;
	if(x<0)x+=mod;
}
int main()
{
	//freopen("sol.in","r",stdin);
	//freopen("sol.out","w",stdout);
	//mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
	ios_base::sync_with_stdio(false);cin.tie(0);cerr.tie(0);cout.tie(0);
	cin>>s;
	n=s.size();
	for(i=1;i<=n;i++)c[i]=s[i-1];
	pw[0]=1;
	for(i=1;i<=n;i++)pw[i]=(pw[i-1]*p)%mod;
	in=129032259;
	for(i=1;i<=n;i++)
	{
		x=0;
		mp.clear();
		for(r=1;r<i;r++)
		{
			ad(x,pw[r-1]*c[r]%mod);
		}
		for(r=i;r<=n;r++)
		{
			ad(x,pw[i-1]*c[r]%mod);
			l=r-i+1;
			if(i==1)b[l][r]=1;
			else if(i==2 && c[r]==c[l])b[l][r]=1;
			else if(i==3 && c[r]==c[l])b[l][r]=1;
			else if(i>3 && c[r]==c[l] && b[l+1][r-1])b[l][r]=1;
			if(b[l][r])
			{
				mp[x]++;
				rs=max(rs,i*mp[x]);
			}
			ad(x,-c[r-i+1]);
			x=(x*in)%mod;
		}
	}
	cout<<rs<<endl;
	return 0;
}

Compilation message (stderr)

palindrome.cpp:2:0: warning: ignoring #pragma GCC optimization [-Wunknown-pragmas]
 #pragma GCC optimization("O3")
 
palindrome.cpp:3:0: warning: ignoring #pragma GCC optimization [-Wunknown-pragmas]
 #pragma GCC optimization("unroll-loops")

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