BZOJ4566 Haoi2016 找相同字符【广义后缀自动机】

Description

给定两个字符串，求出在两个字符串中各取出一个子串使得这两个子串相同的方案数。两个方案不同当且仅当这两
个子串中有一个位置不同。

Input

两行，两个字符串s1，s2，长度分别为n1，n2。1 <=n1, n2<= 200000，字符串中只有小写字母

Output

输出一个整数表示答案

Sample Input

aabb
bbaa

Sample Output

10

---

可以说是模板了
因为只有两个串，所以完全没有必要建trie
直接分别添加，在每个串开始添加之前让last=root就可以了
然后在extend上面加上已经有转移的特判
注意要后缀自动机建完之后再添加right标记
不然会出问题

---

//Author: dream_maker
#include<bits/stdc++.h>
using namespace std;
//----------------------------------------------
//typename
typedef long long ll;
//convenient for
#define for_up(a, b, c) for (int a = b; a <= c; ++a)
#define for_down(a, b, c) for (int a = b; a >= c; --a)
#define for_vector(a, b) for (int a = 0; a < (signed)b.size(); ++a)
//inf of different typename
const int INF_of_int = 1e9;
const ll INF_of_ll = 1e18;
//fast read and write
template <typename T>
void Read(T &x){
  bool w = 1;x = 0;
  char c = getchar();
  while(!isdigit(c) && c != '-')c = getchar();
  if(c == '-')w = 0, c = getchar();
  while(isdigit(c)) {
    x = (x<<1) + (x<<3) + c -'0';
    c = getchar();
  }
  if(!w)x=-x;
}
template <typename T>
void Write(T x){
  if(x < 0) {
    putchar('-');
    x=-x; 
  }
  if(x > 9)Write(x / 10);
  putchar(x % 10 + '0');
}
//----------------------------------------------
const int CHARSET_SIZE = 26;
const int N = 4e5 + 10;
struct Sam {
  Sam *ch[CHARSET_SIZE], *prt;
  int maxl, right[2];
  Sam (int maxl = 0):ch(),prt(NULL),maxl(maxl){
    right[0] = right[1] = 0;
  }
}pool[N<<1],*cur = pool, *root = new (cur++)Sam, *last = root;
int buc[N];
vector<Sam*> topo;
ll ans = 0;
void extend(int c){
  if (last->ch[c] && last->maxl + 1 == last->ch[c]->maxl) {
    last = last->ch[c];
    return;
  }
  Sam *u = new (cur++)Sam(last->maxl + 1), *v = last;
  for (; v && !v->ch[c]; v = v->prt) v->ch[c] = u;
  if (!v) {
    u->prt = root;
  } else if (v->maxl + 1 == v->ch[c]->maxl) {
    u->prt = v->ch[c];
  } else {
    Sam *n = new (cur++)Sam(v->maxl + 1), *o = v->ch[c];
    copy(o->ch, o->ch + CHARSET_SIZE, n->ch);
    n->prt = o->prt;
    o->prt = u->prt = n;
    for (; v && v->ch[c] == o;v = v->prt) v->ch[c] = n;
  }
  last = u;
}
void toposort(){
  int maxv = 0;
  for (Sam *p = pool; p != cur; ++p){
    maxv = max(maxv, p->maxl);
    buc[p->maxl]++;
  }
  for_up(i, 1, maxv) buc[i] += buc[i-1];
  topo.resize(cur-pool);
  for (Sam *p = pool; p != cur; ++p)topo[--buc[p->maxl]] = p;
  for_down(i, topo.size()-1, 1) {
    Sam *p = topo[i];
    p->prt->right[0] += p->right[0];
    p->prt->right[1] += p->right[1];
    ans += 1ll * (p->maxl - p->prt->maxl) * p->right[0] * p->right[1];
  }
}
char c[2][N];
int main() {
  scanf("%s",c[0] + 1);
  int len0 = strlen(c[0] + 1);
  for_up(i, 1, len0) extend(c[0][i]-'a');
  last = root;
  scanf("%s",c[1] + 1);
  int len1 = strlen(c[1] + 1);
  for_up(i, 1, len1) extend(c[1][i]-'a');
  Sam *now = root;
  for_up(i, 1, len0) {
    now = now->ch[c[0][i]-'a'];
    now->right[0] = 1;
  }
  now = root;
  for_up(i, 1, len1) {
    now = now->ch[c[1][i]-'a'];
    now->right[1] = 1;
  }
  toposort();
  Write(ans);
  return 0;
}