字符串：SAM

HDU4622：区间查询不同子串个数

用后缀自动机预处理出所有区间的不同子串个数

建立n次后缀自动机

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

 const int CHAR = ;
 const int MAXN = ;
 struct SAM_Node
 {
     SAM_Node *fa,*next[CHAR];
     int len;
     int id,pos;
     SAM_Node(){}
     SAM_Node(int _len)
     {
         fa = ;
         len = _len;
         memset(next,,sizeof(next));
     }
 };
 SAM_Node SAM_node[MAXN*], *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 = ;
     SAM_root = SAM_last = newSAM_Node();
     SAM_node[].pos = ;
 }
 void SAM_add(int x,int len)
 {
     SAM_Node *p = SAM_last, *np = newSAM_Node(p->len+);
     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 + )
     {
         np->fa = q;
         return;
     }
     SAM_Node *nq = newSAM_Node(q);
     nq->len = p->len + ;
     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 = ;i < len;i++)
         SAM_add(s[i] - 'a',i+);
 }

 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,,sizeof(Q));
         for(int i = ;i < n;i++)
         {
             SAM_init();
             for(int j = i;j < n;j++)
             {
                 SAM_add(str[j]-'a',j-i+);
             }
             for(int j = ;j < SAM_size;j++)
             {
                 Q[i][SAM_node[j].pos-+i]+=SAM_node[j].len - SAM_node[j].fa->len;
             }
             for(int j = i+;j < n;j++)
                 Q[i][j] += Q[i][j-];
         }
         int M;
         int u,v;
         scanf("%d",&M);
         while(M--)
         {
             scanf("%d%d",&u,&v);
             u--;v--;
             printf("%d\n",Q[u][v]);
         }
     }
     return ;
 }

此题也有字符串哈希做法

没看懂就不贴了