[bzoj-2049][Sdoi2008]Cave 洞穴勘测 题解

题目传送门
这题就是一个dalao告诉我的lct裸题，用来练习模板，然而一次都没写过的我果断去看了hzw学长的代码，以此为模板练练手（然而还是不是很会写）
代码：

#include<iostream>#include<cmath>#include<cstdio>#include<cstring>#include<algorithm>#include<queue>#define rep(i,a,n) for (int i=a;i<=n;i++)#define per(i,a,n) for (int i=a;i>=n;i--)#define Clear(a,x) memset(a,x,sizeof(a))#define ll long long#define INF 2000000000#define eps 1e-8using namespace std;ll read(){    ll x=0,f=1;    char ch=getchar();    while (ch<'0'||ch>'9') f=ch=='-'?-1:f,ch=getchar();    while (ch>='0'&&ch<='9') x=x*10+ch-'0',ch=getchar();    return x*f;}const int maxn=10005;int n,m;int fa[maxn],c[maxn][2],q[maxn];bool rev[maxn];char ch[10];bool isroot(int x){    return c[fa[x]][0]!=x&&c[fa[x]][1]!=x;  }void down(int x){    int l=c[x][0],r=c[x][1];    if (rev[x]){        rev[x]^=1;        rev[l]^=1,rev[r]^=1;        swap(c[x][0],c[x][1]);    }}void rotate(int x){    int y=fa[x],z=fa[y],l,r;    if (c[y][0]==x) l=0;        else l=1;    r=l^1;    if (!isroot(y))        if (c[z][0]==y) c[z][0]=x;            else c[z][1]=x;    fa[x]=z;fa[y]=x;fa[c[x][r]]=y;    c[y][l]=c[x][r];    c[x][r]=y;}void splay(int x){    int top=0;    q[++top]=x;    for (int i=x;!isroot(i);i=fa[i])        q[++top]=fa[i];    for (int i=top;i;i--) down(q[i]);    while (!isroot(x)){        int y=fa[x],z=fa[y];        if (!isroot(y)){            if (c[y][0]==x^c[z][0]==y) rotate(x);                else rotate(y);        }        rotate(x);    }}void access(int x){    int t=0;    while (x){        splay(x);        c[x][1]=t;        t=x;x=fa[x];    }}void rever(int x){    access(x);splay(x);rev[x]^=1;}void Link(int x,int y){    rever(x);    fa[x]=y;    splay(x);}void Cut(int x,int y){    rever(x);access(y);splay(y);    c[y][0]=fa[x]=0;}int find(int x){    access(x);splay(x);    int y=x;    while (c[y][0]) y=c[y][0];    return y;}int main(){    n=read(),m=read();    rep(i,1,m){        scanf("%s",ch);        int x=read(),y=read();        if (ch[0]=='C') Link(x,y);            else if (ch[0]=='D') Cut(x,y);                else if (find(x)==find(y)) puts("Yes");                        else puts("No");    }    return 0;}