Submission #530838

#	Time	Username	Problem	Language	Result	Execution time	Memory
530838		new_acc	Palindromes (APIO14_palindrome)	C++14	100 / 100	159 ms	92364 KiB

palindrome

#include<bits/stdc++.h>
#define fi first
#define se second
#define pitem item*
using namespace std;
typedef long long ll;
typedef vector<ll> vi;
typedef vector<ll> vl;
struct item{
	pitem fail;
	int l,il;
	pitem g[27];
};
const int N=3e5+10;
string s;
item *k1,*k2;
vector<pitem> k[N];
pitem add(int ind,pitem curr){
	while(curr!=nullptr){
		if(ind+1>=(curr->l)+2 and s[ind-(curr->l)-1]==s[ind]) break;
		curr=curr->fail;
	}
	if(curr->g[int(s[ind])-96]!=nullptr) {
		curr->g[int(s[ind])-96]->il++;
		return curr->g[int(s[ind])-96];
	}
	curr->g[int(s[ind])-96]=new item;
	curr->g[int(s[ind])-96]->il=1;
	curr->g[int(s[ind]-96)]->l=curr->l+2;
	for(int i=1;i<=26;i++) curr->g[int(s[ind])-96]->g[i]=nullptr;
	pitem pom=curr->g[int(s[ind])-96];
	curr=curr->fail;	
	while(curr!=nullptr){	
		if(ind+1>=(curr->l)+2 and s[ind-(curr->l)-1]==s[ind]) break;
		curr=curr->fail;
	}
	if(curr==nullptr) pom->fail=k2;
	else pom->fail=curr->g[int(s[ind])-96];
	return pom;
}
void rek(pitem curr){
	if(!curr) return;
	k[curr->l].push_back(curr);
	for(int i=1;i<=26;i++) rek(curr->g[i]);
}
void solve(){
	cin>>s;
	k1=new item;
	k2=new item;
	k2->fail=k1,k1->fail=nullptr;
	k1->l=-1,k2->l=0,k1->il=0,k2->il=0;
	for(int i=1;i<=26;i++) k1->g[i]=nullptr,k2->g[i]=nullptr;
	pitem curr=k2;
	for(int i=0;i<s.size();i++) curr=add(i,curr);
	rek(k1),rek(k2);
	ll res=0;
	for(int i=s.size();i>=1;i--){
		for(auto u:k[i]){
			res=max(res,(ll)(u->il)*(ll)(u->l));
			u->fail->il+=u->il;
		}
	}
	cout<<res<<"\n";
}
int main(){
	ios_base::sync_with_stdio(0),cin.tie(0);
	solve();
}

Compilation message (stderr)

palindrome.cpp: In function 'void solve()':
palindrome.cpp:54:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   54 |  for(int i=0;i<s.size();i++) curr=add(i,curr);
      |              ~^~~~~~~~~

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