COJ885 LCS？？？

#include<cstdio>
#include<cctype>
#include<queue>
#include<cstring>
#include<algorithm>
#define rep(s,t) for(int i=s;i<=t;i++)
#define ren for(int i=first[x];i!=-1;i=next[i])
using namespace std;
inline int read() {
int x=0,f=1;char c=getchar();
for(;!isdigit(c);c=getchar()) if(c=='-') f=-1;
for(;isdigit(c);c=getchar()) x=x*10+c-'0';
return x*f;
}
const int maxn=200010;
int l[maxn],fa[maxn],to[maxn][2],last=1,cnt=1;
void extend(int c) {
int p,q,np,nq;
p=last;l[np=last=++cnt]=l[p]+1;
for(;!to[p][c];p=fa[p]) to[p][c]=np;
if(!p) fa[np]=1;
else {
q=to[p][c];
if(l[p]+1==l[q]) fa[np]=q;
else {
l[nq=++cnt]=l[p]+1;
memcpy(to[nq],to[q],sizeof(to[nq]));
fa[nq]=fa[q];
fa[q]=fa[np]=nq;
for(;to[p][c]==q;p=fa[p]) to[p][c]=nq;
}
}
}
char s[maxn];
int main() {
scanf("%s",s);int n=strlen(s),p=1,ans=0,cur=0;
rep(0,n-1) extend(s[i]-'a');
scanf("%s",s);n=strlen(s);
rep(0,n-1) {
int c=s[i]-'a';
if(to[p][c]) p=to[p][c],cur++;
else {
while(p&&!to[p][c]) p=fa[p];
if(!p) p=1,cur=0;
else cur=l[p]+1,p=to[p][c];
}
ans=max(ans,cur);
}
printf("%d\n",ans);
return 0;
}