优化的后缀数组，o(n)算法解决查询区间内不同子串个数以及两个字符串的最长公共子串问题
1.查询一个区间内不同子串的个数
http://www.cnblogs.com/kuangbin/p/3239825.html

#include <stdio.h>
#include <string.h>
#include <algorithm>
#include <iostream>
using namespace std;

const int CHAR = 26;
const int MAXN = 2020;
struct SAM_Node
{
    SAM_Node *fa,*next[CHAR];
    int len;
    int id,pos;
    SAM_Node(){}
    SAM_Node(int _len)
    {
        fa = 0;
        len = _len;
        memset(next,0,sizeof(next));
    }
};
SAM_Node SAM_node[MAXN*2], *SAM_root, *SAM_last;
int SAM_size;
SAM_Node *newSAM_Node(int len)
{
    SAM_node[SAM_size] = SAM_Node(len);
    SAM_node[SAM_size].id = SAM_size;
    return &SAM_node[SAM_size++];
}
SAM_Node *newSAM_Node(SAM_Node *p)
{
    SAM_node[SAM_size] = *p;
    SAM_node[SAM_size].id = SAM_size;
    return &SAM_node[SAM_size++];
}
void SAM_init()
{
    SAM_size = 0;
    SAM_root = SAM_last = newSAM_Node(0);
    SAM_node[0].pos = 0;
}
void SAM_add(int x,int len)
{
    SAM_Node *p = SAM_last, *np = newSAM_Node(p->len+1);
    np->pos = len;
    SAM_last = np;
    for(;p && !p->next[x];p = p->fa)
        p->next[x] = np;
    if(!p)
    {
        np->fa = SAM_root;
        return;
    }
    SAM_Node *q = p->next[x];
    if(q->len == p->len + 1)
    {
        np->fa = q;
        return;
    }
    SAM_Node *nq = newSAM_Node(q);
    nq->len = p->len + 1;
    q->fa = nq;
    np->fa = nq;
    for(;p && p->next[x] == q;p = p->fa)
        p->next[x] = nq;
}
void SAM_build(char *s)
{
    SAM_init();
    int len = strlen(s);
    for(int i = 0;i < len;i++)
        SAM_add(s[i] - 'a',i+1);
}

int Q[MAXN][MAXN];
char str[MAXN];
int main()
{
    int T;
    scanf("%d",&T);
    while(T--)
    {
        scanf("%s",str);
        int n = strlen(str);
        memset(Q,0,sizeof(Q));
        for(int i = 0;i < n;i++)
        {
            SAM_init();
            for(int j = i;j < n;j++)
            {
                SAM_add(str[j]-'a',j-i+1);
            }
            for(int j = 1;j < SAM_size;j++)
            {
                Q[i][SAM_node[j].pos-1+i]+=SAM_node[j].len - SAM_node[j].fa->len;
            }
            for(int j = i+1;j < n;j++)
                Q[i][j] += Q[i][j-1];
        }
        int M;
        int u,v;
        scanf("%d",&M);
        while(M--)
        {
            scanf("%d%d",&u,&v);
            u--;v--;
            printf("%d\n",Q[u][v]);
        }
    }
    return 0;
}

后缀自动机 求两个字符串的最长公共子串长度
http://www.cnblogs.com/kuangbin/p/3309059.html

#include <stdio.h>
#include <string.h>
#include <iostream>
#include <algorithm>
#include <vector>
#include <queue>
#include <set>
#include <map>
#include <string>
#include <math.h>
#include <stdlib.h>
#include <time.h>
using namespace std;

const int CHAR = 26;
const int MAXN = 250010;
struct SAM_Node
{
    SAM_Node *fa, *next[CHAR];
    int len;
    int id, pos;
    SAM_Node(){}
    SAM_Node(int _len)
    {
        fa = 0;
        len = _len;
        memset(next,0,sizeof(next));
    }
};
SAM_Node SAM_node[MAXN*2], *SAM_root, *SAM_last;
int SAM_size;
SAM_Node *newSAM_Node(int len)
{
    SAM_node[SAM_size] = SAM_Node(len);
    SAM_node[SAM_size].id = SAM_size;
    return &SAM_node[SAM_size++];
}
SAM_Node *newSAM_Node(SAM_Node *p)
{
    SAM_node[SAM_size] = *p;
    SAM_node[SAM_size].id = SAM_size;
    return &SAM_node[SAM_size++];
}
void SAM_init()
{
    SAM_size = 0;
    SAM_root = SAM_last = newSAM_Node(0);
    SAM_node[0].pos = 0;
}
void SAM_add(int x,int len)
{
    SAM_Node *p = SAM_last, *np = newSAM_Node(p->len + 1);
    np->pos = len;
    SAM_last = np;
    for(; p && !p->next[x];p = p->fa)
        p->next[x] = np;
    if(!p)
    {
        np->fa = SAM_root;
        return;
    }
    SAM_Node *q = p->next[x];
    if(q->len == p->len + 1)
    {
        np->fa = q;
        return;
    }
    SAM_Node *nq = newSAM_Node(q);
    nq->len = p->len + 1;
    q->fa = nq;
    np->fa = nq;
    for(; p && p->next[x] == q; p = p->fa)
        p->next[x] = nq;
}
void SAM_build(char *s)
{
    SAM_init();
    int len = strlen(s);
    for(int i = 0;i < len;i++)
        SAM_add(s[i] - 'a', i+1);
}
char str1[MAXN], str2[MAXN];
int main()
{
    //freopen("in.txt","r",stdin);
    //freopen("out.txt","w",stdout);
    while(scanf("%s%s",str1,str2) == 2)
    {
        SAM_build(str1);
        int len = strlen(str2);
        SAM_Node *tmp = SAM_root;
        int ans = 0;
        int t = 0;
        for(int i = 0;i < len;i++)
        {
            if(tmp->next[str2[i]-'a'])
            {
                tmp = tmp->next[str2[i]-'a'];
                t++;
            }
            else
            {
                while(tmp && !tmp->next[str2[i]-'a'])
                    tmp = tmp->fa;
                if(tmp == NULL)
                {
                    tmp = SAM_root;
                    t = 0;
                }
                else
                {
                    t = tmp->len + 1;
                    tmp = tmp->next[str2[i]-'a'];
                }
            }
            ans = max(ans,t);
        }
        printf("%d\n",ans);
    }
    return 0;
}