hdu_1403_SAM_求最小公共前缀

题目： click here

就是求最小公共前缀

#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <algorithm>
using namespace std;

const int MAX_NODES = 3555555;
const int N = 1111111;
struct node{
struct node *ch[26];
struct node *f;
int mx;
void init(){
memset(ch,0,sizeof(ch));
f = 0;
}
}*root,*cnt,*tail,pool[MAX_NODES];
char s
,ts
;
int n;
void insert(int c,int len){
node *p = tail, *np = cnt++;
for( ; p && !p->ch[c] ; p = p->f) p->ch[c] = np;
np->mx = len;
tail = np;
if(!p) np->f = root;
else
if( p->ch[c]->mx == p->mx+1) np->f = p->ch[c];
else{
node *q = p->ch[c], *r = cnt++;
*r = *q;
r->mx = p->mx+1;
q->f = np->f = r;
for( ; p && p->ch[c] == q ; p = p->f) p->ch[c] = r;
}
}
void init_suffix_auto(char s[]){
int len = 0;
tail = cnt = root = pool; cnt++ , root->init();
for(int i = 0;i < (n<<1) ;i++)
pool[i].init();
for( ; s[len] ; len++){
insert(s[len] - 'a', len+1);
}
}

int main(){
int t;
while(scanf("%s",s)!=EOF){
scanf("%s",ts);
n = strlen(s);
init_suffix_auto(s);
node *p=root;
int ans = 0,tmp=0;
for(int i = 0; ts[i]; i++){
int id = ts[i]-'a';
if(p->ch[id]){
p = p->ch[id];
tmp++;
}else{
for(; p && !p->ch[id]; p = p->f)
;
if(!p){
p = root;
tmp = 0;
}else{
tmp = p->mx+1;
p = p->ch[id];
}
}
ans = max(tmp,ans);
}
printf("%d\n",ans);
}
return 0;
}