BZOJ 2049 洞穴勘测

又一道LCT模板题。

如何找是不是在同一棵树上？只要找深度最小的点是不是相同的点即可。

也就是splay最左边的那个点。

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#define maxv 10050
#define maxe 20050
using namespace std;
int n,m,fath[maxv],size[maxv],tree[maxv][3],x,y,rev[maxv];
int stack[maxv],top=0;
char s[20];
bool isroot(int x)
{
    return tree[fath[x]][1]!=x&&tree[fath[x]][2]!=x;
}
void pushdown(int x)
{
    if (rev[x])
    {
        int ls=tree[x][1],rs=tree[x][2];
        rev[ls]^=1;rev[rs]^=1;rev[x]=0;
        swap(tree[x][1],tree[x][2]);
    }
}
void pushup(int x)
{
    int ls=tree[x][1],rs=tree[x][2];
    size[x]=size[ls]+size[rs]+1;
}
void rotate(int x)
{
    int y=fath[x],z=fath[y],l,r;
    if (tree[y][1]==x) l=1;else l=2;
    r=3-l;
    if (!isroot(y))
    {
        if (tree[z][1]==y) tree[z][1]=x;
        else tree[z][2]=x;
    }
    fath[x]=z;fath[y]=x;fath[tree[x][r]]=y;
    tree[y][l]=tree[x][r];tree[x][r]=y;
    pushup(y);pushup(x);
}
void splay(int x)
{
    top=0;
    stack[++top]=x;
    for (int i=x;!isroot(i);i=fath[i])
        stack[++top]=fath[i];
    for (int i=top;i>=1;i--)
        pushdown(stack[i]);
    while (!isroot(x))
    {
        int y=fath[x],z=fath[y];
        if (!isroot(y))
        {
            if ((tree[y][1]==x)^(tree[z][1]==y)) rotate(x);
            else rotate(y);
        }
        rotate(x);
    }
}
void access(int x)
{
    int regis=0;
    while (x)
    {
        splay(x);
        tree[x][2]=regis;
        regis=x;x=fath[x];
    }
}
void makeroot(int x)
{
    access(x);
    splay(x);
    rev[x]^=1;
}
void link()
{
    scanf("%d%d",&x,&y);
    makeroot(x);
    fath[x]=y;
    splay(x);
}
void cut()
{
    scanf("%d%d",&x,&y);
    makeroot(x);access(y);
    splay(y);tree[y][1]=0;fath[x]=0;
}
int find(int x)
{
    access(x);splay(x);
    int y=x;
    while (tree[y][1]) y=tree[y][1];
    return y;
}
void query()
{
    scanf("%d%d",&x,&y);
    int u=find(x),v=find(y);
    if (u==v)
        printf("Yes\n");
    else printf("No\n");
}
int main()
{
    scanf("%d%d",&n,&m);
    for (int i=1;i<=n;i++) size[i]=1;
    for (int i=1;i<=m;i++)
    {
        scanf("%s",s);
        if (s[0]=='C') link();
        else if (s[0]=='D') cut();
        else if (s[0]=='Q') query();
    }
    return 0;
}