[BZOJ2049][SDOI2008]洞穴勘测（动态树LCT）

LCT模板题。
对于Connect操作，就执行Link(u,v)，即连边(u,v)。
对于Destroy操作，就执行Cut(u,v)，即删边(u,v)。
对于Query操作，就判断是否FindRoot(u)==FindRoot(v)，即判断是否在同一个连通块内。
代码：

#include <cmath>#include <cstdio>#include <cstring>#include <iostream>#include <algorithm>using namespace std;inline int read() {    int res = 0; bool bo = 0; char c;    while (((c = getchar()) < '0' || c > '9') && c != '-');    if (c == '-') bo = 1; else res = c - 48;    while ((c = getchar()) >= '0' && c <= '9')        res = (res << 3) + (res << 1) + (c - 48);    return bo ? ~res + 1 : res;}inline char get() {    char c; while ((c = getchar()) != 'C' && c != 'D' && c != 'Q');    return c;}const int N = 5e4 + 5;int n, Q, fa[N], lc[N], rc[N], rev[N], que[N], len;int which(int x) {return rc[fa[x]] == x;}bool is_root(int x) {    return !fa[x] || (lc[fa[x]] != x && rc[fa[x]] != x);}void down(int x) {    if (rev[x]) {        swap(lc[x], rc[x]);        if (lc[x]) rev[lc[x]] ^= 1;        if (rc[x]) rev[rc[x]] ^= 1;        rev[x] = 0;    }}void rotate(int x) {    int y = fa[x], z = fa[y], b = lc[y] == x ? rc[x] : lc[x];    if (z && !is_root(y)) (lc[z] == y ? lc[z] : rc[z]) = x;    fa[x] = z; fa[y] = x; b ? fa[b] = y : 0;    if (lc[y] == x) rc[x] = y, lc[y] = b;    else lc[x] = y, rc[y] = b;}void splay(int x) {    int i, y; que[len = 1] = x;    for (y = x; !is_root(y); y = fa[y]) que[++len] = fa[y];    for (i = len; i >= 1; i--) down(que[i]);    while (!is_root(x)) {        if (!is_root(fa[x])) {            if (which(x) == which(fa[x])) rotate(fa[x]);            else rotate(x);        }        rotate(x);    }}void Access(int x) {    int y;    for (y = 0; x; y = x, x = fa[x]) {        splay(x); rc[x] = y;        if (y) fa[y] = x;    }}int Find_Root(int x) {    Access(x); splay(x);    while (down(x), lc[x]) x = lc[x];    splay(x); return x;}void Make_Root(int x) {    Access(x); splay(x);    rev[x] ^= 1;}void Link(int x, int y) {    Make_Root(x); fa[x] = y;}void Cut(int x, int y) {    Make_Root(x); Access(y); splay(y);    lc[y] = 0; fa[x] = 0;}int main() {    int i, x, y; n = read(); Q = read(); char op;    while (Q--) {        op = get(); x = read(); y = read();        if (op == 'C') Link(x, y);        else if (op == 'D') Cut(x, y);        else printf(Find_Root(x) == Find_Root(y) ? "Yes\n" : "No\n");    }    return 0;}