Submission #31178

#	Time	Username	Problem	Language	Result	Execution time	Memory
31178		tatatan	Palindromes (APIO14_palindrome)	C++11	100 / 100	19 ms	37912 KiB

palindrome

#include <bits/stdc++.h>
#define mp make_pair
#define pb push_back
#define pii pair<int,int>
#define LL long long
#define st first
#define nd second
#define endl '\n'
using namespace std;
const int N=3e5+5;
int suff[N],len[N],lz[N],nxt[N][26],cur,tt=3;
LL ans;
string s;
stack<int> st;
void add(int x) {
	while(s[x-len[cur]-1]!=s[x]) 
		cur=suff[cur];
	int y=s[x]-'a';
	if(nxt[cur][y]) {
		cur=nxt[cur][y];
		++lz[cur];
		return;
	}
	int nw=tt++;
	st.push(nw);
	++lz[nw];
	len[nw]=len[cur]+2;
	if(len[nw]==1) {
		suff[nw]=2;
		nxt[cur][y]=nw;
		cur=nw;
		return;
	}
	int tmp2=cur;
	cur=suff[cur];
	while(s[x-len[cur]-1]!=s[x]) 
		cur=suff[cur];
	suff[nw]=nxt[cur][y];
	cur=nw;
	nxt[tmp2][y]=cur;
}
int main() {
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	cin>>s;
	len[1]=-1; suff[1]=1;
	len[2]=0; suff[2]=1;
	cur=1;
	for(int i=0;i<s.size();++i) 
		add(i);
	while(!st.empty()) {
		int x=st.top();
		st.pop();
		ans=max(ans,1LL*len[x]*lz[x]);
		lz[suff[x]]+=lz[x];
	}
	cout<<ans<<endl;
}

Compilation message (stderr)

palindrome.cpp: In function 'int main()':
palindrome.cpp:49:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<s.size();++i) 
               ^

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