WA37分 求调

#include <bits/stdc++.h>
using namespace std;
char a[100010],s[200010],n;
int p[200010],l[200010],r[200010],ans;
int main(){
	scanf("%s",a+1);
	int sz=strlen(a+1);
	s[n]='$';
	s[++n]='#';
	for(int i=1;i<=sz;i++){
		s[++n]=a[i];
		s[++n]='#';
	}
	s[++n]='@';
	int mx=0,mxi=0;
	for(int i=1;i<=n;i++){
		if(mx>i) p[i]=min(p[2*mxi-i],mx-i);
		else p[i]=1;
		while(s[i-p[i]]==s[i+p[i]]) p[i]++;
		if(i+p[i]>mx){
			mx=i+p[i];
			mxi=i;
		}
		l[i-p[i]+1]=max(l[i-p[i]+1],p[i]-1);
		r[i+p[i]-1]=max(r[i+p[i]-1],p[i]-1);
	}
	for(int i=3;i<n;i+=2) l[i]=max(l[i],l[i-2]-2);
	for(int i=n-1;i>=3;i-=2) r[i]=max(r[i],r[i+2]-2);
	for(int i=3;i<n;i+=2) if(l[i]&&r[i]) ans=max(ans,l[i]+r[i]);
	printf("%d\n",ans);
	return 0;
}