============数据结构模板================

动态树
动态树是一类要求维护森林的连通性的题的总称，这类问题要求维护某个点到根的某些数据，支持树的切分，合并，以及对子树的某些操作。其中解决这一问题的某些简化版（不包括对子树的操作）的基础数据结构就是LCT(link-cut tree)。

const int MAXN = 100010;
struct Node
{
    Node *ch[2], *p;
    int size, value;
    bool rev;
    Node(int t = 0);
    inline bool dir(void)
    {
        return p->ch[1] == this;
    }
    inline void SetC(Node *x, bool d)
    {
        ch[d] = x;
        x->p = this;
    }
    inline void Rev(void)
    {
        swap(ch[0], ch[1]);
        rev ^= 1;
    }
    inline void Push(void)
    {
        if (rev)
        {
            ch[0]->Rev();
            ch[1]->Rev();
            rev = 0;
        }
    }
    inline void Update(void)
    {
        size = ch[0]->size + ch[1]->size + 1;
    }
} Tnull, *null = &Tnull, *fim[MAXN];
// 要记得额外更新null的信息
Node::Node(int _value)
{
    ch[0] = ch[1] = p = null;
    rev = 0;
}
inline bool isRoot(Node *x)
{
    return x->p == null || (x != x->p->ch[0] && x != x->p->ch[1]);
}
inline void rotate(Node *x)
{
    Node *p = x->p;
    bool d = x->dir();
    p->Push();
    x->Push();
    if (!isRoot(p)) p->p->SetC(x, p->dir());
    else x->p = p->p;
    p->SetC(x->ch[!d], d);
    x->SetC(p, !d);
    p->Update();
}
inline void splay(Node *x)
{
    x->Push();
    while (!isRoot(x))
    {
        if (isRoot(x->p)) rotate(x);
        else
        {
            if (x->dir() == x->p->dir())
            {
                rotate(x->p);
                rotate(x);
            }
            else
            {
                rotate(x);
                rotate(x);
            }
        }
    }
    x->Update();
}
inline Node* Access(Node *x)
{
    Node *t = x, *q = null;
    for (; x != null; x = x->p)
    {
        splay(x);
        x->ch[1] = q;
        q = x;
    }
    splay(t); //info will be updated in the splay;
    return q;
}
inline void Evert(Node *x)
{
    Access(x);
    x->Rev();
}
inline void link(Node *x, Node *y)
{
    Evert(x);
    x->p = y;
}
inline Node* getRoot(Node *x)
{
    Node *tmp = x;
    Access(x);
    while (tmp->Push(), tmp->ch[0] != null) tmp = tmp->ch[0];
    splay(tmp);
    return tmp;
}
// 一定要确定x和y之间有边
inline void cut(Node *x, Node *y)
{
    Access(x);
    splay(y);
    if (y->p != x) swap(x, y);
    Access(x);
    splay(y);
    y->p = null;
}
inline Node* getPath(Node *x, Node *y)
{
    Evert(x);
    Access(y);
    return y;
}
inline void clear(void)
{
    null->rev = 0;
    null->sie = 0;
    null->value = 0;
}

splay树模板，分为两个部分，第一个部分为splay当作平衡树使用，第二个部分为splay当作线段树维护序列使用。注意在每次Insert之后都要splay其返回值到根
// 最大可能的节点数
const int MAXN = 100010;
// 每个打标记的操作就是更新这个节点的信息，然后对子节点打标记
struct Node
{
    Node *ch[2], *p;
    int size, value;
    bool rev;
    inline bool dir(void)
    {
        return p->ch[1] == this;
    }
    inline void SetC(Node *x, bool d)
    {
        ch[d] = x;
        x->p = this;
    }
    inline void Rev(void)
    {
        swap(ch[0], ch[1]);
        rev ^= 1;
    }
    // null永远不会push
    inline void Push(void)
    {
        if (rev)
        {
            ch[0]->Rev();
            ch[1]->Rev();
            rev = 0;
        }
    }
    // null永远不会update
    inline void Update(void)
    {
        size = ch[0]->size + ch[1]->size + 1;
    }
    inline void initInfo(void)
    {
        rev = 0;
    }
} Tnull, *null = &Tnull, *data, POOL[MAXN];
class Splay
{
public:
    Node *root;
    inline void rotate(Node *x)
    {
        Node *p = x->p;
        bool d = x->dir();
        p->Push();
        x->Push();
        p->p->SetC(x, p->dir());
        p->SetC(x->ch[!d], d);
        x->SetC(p, !d);
        p->Update();
    }
    inline void splay(Node *x, Node *G)
    {
        if (G == null) root = x;
        while (x->p != G)
        {
            if (x->p->p == G) rotate(x);
            else
            {
                if (x->dir() == x->p->dir())
                {
                    rotate(x->p);
                    rotate(x);
                }
                else
                {
                    rotate(x);
                    rotate(x);
                }
            }
        }
        x->Push();
        x->Update();
    }
    inline Node* Renew(int value)
    {
        Node *ret = data++;
        ret->ch[0] = ret->ch[1] =ret->p = null;
        ret->size = 1;
        ret->value = value;
        ret->initInfo();
        return ret;
    }
    inline Node* getMin(Node *x)
    {
        Node *tmp = x;
        while (tmp->ch[0] != null) tmp = tmp->ch[0];
        return tmp;
    }
    inline Node* getMax(Node *x)
    {
        Node *tmp = x;
        while (tmp->ch[1] != null) tmp = tmp->ch[1];
        return tmp;
    }
    // 查询第k大
    inline Node* getKth(int k)
    {
        Node *tmp = root;
        assert(k > 0 && k <= root->size);
        while (true)
        {
            tmp->Push();
            if (tmp->ch[0]->size + 1 == k) return tmp;
            if (tmp->ch[0]->size >= k) tmp = tmp->ch[0];
            else k -= tmp->ch[0]->size + 1, tmp = tmp->ch[1];
        }
    }
    // 以下为splay当作平衡树使用
    // 查找树中value = v的元素, 返回之后splay
    inline Node* find(int v)
    {
        Node *tmp = root;
        while (tmp != null)
        {
            tmp->Push();
            if (tmp->value == v) return tmp;
            if (v < tmp->value) tmp = tmp->ch[0];
            else tmp = tmp->ch[1];
        }
        return null;
    }
    // 统计有多少元素小于等于v, 当flag = 1时，统计多少元素严格小于v, 一定要记得splay最后的那个tmp
    inline int Count(int v, bool flag = 0)
    {
        Node *tmp = root, *last = null;
        int ret = 0;
        while (tmp != null)
        {
            tmp->Push();
            last = tmp;
            if ((!flag && tmp->value > v) || (flag && tmp->value >= v))
            {
                tmp = tmp->ch[0];
            }
            else ret += tmp->ch[0]->size + 1, tmp = tmp->ch[1];
        }
        if (last != null) splay(last, null);
        return ret;
    }
    // 删除x这个结点
    inline void erase(Node* x)
    {
        splay(x, null);
        if (x->ch[0] == null || x->ch[1] == null)
        {
            int d = x->ch[1] != null;
            root = x->ch[d];
            root->p = null;
            return;
        }
        Node *L = getMax(x->ch[0]), *R = getMax(x->ch[1]);
        splay(L, x);
        splay(R, x);
        L->SetC(R, 1);
        L->p = null;
        root = L;
        L->Update();
    }
    // 插入一个值为value的节点，初始要以Insert(root, null, value)来调用, 返回之后splay
    inline Node* Insert(Node *&now, Node* father, int value)
    {
        if (now == null)
        {
            now = Renew(value);
            now->p = father;
            return now;
        }
        Node *ret;
        now->Push();
        if (value <= now->value) ret = Insert(now->ch[0], now, value);
        else ret = Insert(now->ch[1], now, value);
        now->Update();
        return ret;
    }
    // 以下为splay维护序列, 初始要在原序列中放入一个-inf和inf来防止边界条件
    // 得到原数列中[l,r]区间对应的结点，如果l == r + 1则表示是一个空区间
    inline Node* getInterval(int l, int r)
    {
        assert(l <= r + 1);
        Node *L = getKth(l), *R = getKth(r + 2);
        splay(L, null);
        splay(R, L);
        return R->ch[0];
    }
    // 删除一段区间[l,r]
    inline void eraseInterval(int l, int r)
    {
        getInterval(l, r);
        root->ch[1]->ch[0] = null;
        root->ch[1]->Update();
        root->Update();
    }
    // 在位置l的后面插入一段区间x (0 <= l <= n)
    inline void insertInterval(int l, Node *x)
    {
        Node *L = getKth(l + 1), *R = getKth(l + 2);
        splay(L, null);
        splay(R, L);
        R->SetC(x, 0);
        R->Update();
        L->Update();
    }
    // 把数列a的[l,r]构建为一个splay
    inline Node* Build(int l, int r, int a[])
    {
        if (l > r) return null;
        int mid = (l + r) >> 1;
        Node *ret = Renew(a[mid]);
        if (l == r) return ret;
        ret->SetC(Build(l, mid - 1, a), 0);
        ret->SetC(Build(mid + 1, r, a), 1);
        ret->Update();
        return ret;
    }
} T;
void clear(void)
{
    data = POOL;
    T.root = null;
}

倍增算法构建后缀数组，时间复杂度为 $O(n \lg n)$. 注意字符串和最终的后缀数组均从 1 开始编号. 要保证字符串中都为大于0的字符, 而且字符串的第n+1位应该为0.
// string is 1-base, sa is 1-base
int w[MAXM];
inline void Sort(int a[], int ret[], int n, int m = MAXM - 1)
{
    for (int i = 0; i <= m; i++) w[i] = 0;
    for (int i = 1; i <= n; i++) w[a[i]]++;
    for (int i = 1; i <= m; i++) w[i] += w[i - 1];
    for (int i = n; i >= 1; i--) ret[w[a[i]]--] = i;
}
int wa[MAXN], wb[MAXN], tmp[MAXN];
inline void getSA(int ch[], int sa[], int n)
{
    int *x = wa, *y = wb;
    for (int i = 1; i <= n; i++) x[i] = ch[i];
    Sort(ch, sa, n);
    for (int j = 1, p = 1, m = MAXN - 1; p < n; m = p, j <<= 1)
    {
        p = 0;
        for (int i = n - j + 1; i <= n; i++) y[++p] = i;
        for (int i = 1; i <= n; i++) if (sa[i] > j) y[++p] = sa[i] - j;
        for (int i = 1; i <= n; i++) tmp[i] = x[y[i]];
        Sort(tmp, sa, n, m);
        for (int i = 1; i <= n; i++) sa[i] = y[sa[i]];
        swap(x, y);
        x[sa[1]] = p = 1;
        for (int i = 2; i <= n; i++)
        {
            if (y[sa[i]] == y[sa[i - 1]] && y[sa[i] + j] == y[sa[i - 1] + j]) x[sa[i]] = p;
            else x[sa[i]] = ++p;
        }
    }
    sa[0] = n + 1; // for calculate height.
}
int rank[MAXN];
inline void getHeight(int ch[], int sa[], int height[], int n)
{
    for (int i = 1; i <= n; i++) rank[sa[i]] = i;
    for (int i = 1, t = 0; i <= n; i++)
    {
        if (t > 0) t--;
        while (ch[i + t] == ch[sa[rank[i] - 1] + t]) t++;
        height[rank[i]] = t;
    }
}

构建后缀自动机。统计一个串出现的次数时，只需统计其节点所对应的子树中，end为true的节点的个数即可。将所有节点按val值从小到大排序后即可得到parent树由根开始的BFS序。

struct Node
{
    Node *next[26], *par;
    int val, end; // 26 is volatile
} POOL[MAXN << 1], *data, *root, *last; //Note that the size of POOL should be doubled.
inline void Add(int x)
{
    Node *p = last, *np = data++;
    np->val = p->val + 1;
    np->end = true;
    while (p && !p->next[x])
        p->next[x] = np, p = p->par;
    if (p == 0)
    {
        np->par = root;
    }
    else
    {
        Node *q = p->next[x];
        if (q->val == p->val + 1)
        {
            np->par = q;
        }
        else
        {
            Node *nq = data++;
            nq->val = p->val + 1;
            memcpy(nq->next, q->next, sizeof q->next);
            nq->par = q->par;
            np->par = q->par = nq;
            while (p && p->next[x] == q)
                p->next[x] = nq, p = p->par;
        }
    }
    last = np;
}
void Clear(void)
{
    data = POOL;
    last = root = data++;
}