[ZJOI2015]诸神眷顾的幻想乡（广义后缀自动机）

/*
题目中的神仙性质真的是令人愉悦
因为我一眼看成了每个点的度数不超过二十， 心想这他喵的和字符串什么关系

统计树上不同子串个数， 按道理直接dfs n次把所有的串插到后缀自动机里就行了

但是我们发现当我们从一个不是叶子的节点进行dfs时， 实际上得到的每一个串都是从某个叶子开始bfs产生的某个串的后缀

也就是说不是从叶子开始dfs是没啥用的

找出叶子然后暴力就好了 


*/

#include<cstdio>
#include<algorithm>
#include<cstring>
#include<queue>
#include<iostream>
#define ll long long 
#define M 4000010
#define mmp make_pair
using namespace std;
int read()
{
    int nm = 0, f = 1;
    char c = getchar();
    for(; !isdigit(c); c = getchar()) if(c == '-') f = -1;
    for(; isdigit(c); c = getchar()) nm = nm * 10 + c - '0';
    return nm * f;
}
int ch[M][10], len[M], fa[M], cnt = 1, cor[100100], n, c;
vector<int> to[100010];
 
int insert(int lst, int c)
{
    int p = ++cnt, f = lst;
    len[p] = len[f] + 1;
    while(f && !ch[f][c]) ch[f][c] = p, f = fa[f];
    if(f == 0)
        fa[p] = 1;
    else{
        int q = ch[f][c];
        if(len[q] == len[f] + 1)
        {
            fa[p] = q;
        }
        else
        {
            int nq = ++cnt;
            fa[nq] = fa[q];
            memcpy(ch[nq], ch[q], sizeof(ch[q]));
            len[nq] = len[f] + 1;
            fa[q] = fa[p] = nq;
            while(f && ch[f][c] == q) ch[f][c] = nq, f = fa[f];
        }
    }   
    return p;
}
void dfs(int now, int lst, int pre)
{
    int tmp = insert(pre, cor[now]);
    for(int i = 0; i < to[now].size(); i++)
    {
        int vj = to[now][i];
        if(vj == lst) continue;
        dfs(vj, now, tmp);
    }
}
 
int main()
{
    n = read(), c = read();
    for(int i = 1; i <= n; i++) cor[i] = read();
    for(int i = 1; i < n; i++)
    {
        int vi = read(), vj = read();
        to[vi].push_back(vj);
        to[vj].push_back(vi);
    }
    for(int i = 1; i <= n; i++)
    {
        if(to[i].size() == 1)
        {
            dfs(i, i, 1);
        }
    }
    ll ans = 0;
    for(int i = 1; i <= cnt; i++) ans += len[i] - len[fa[i]];
    cout << ans << "\n";
    return 0;
}

转载于:https://www.cnblogs.com/luoyibujue/p/10669106.html