BZOJ 3306: 树 LCT + set 维护子树信息

可以作为 LCT 维护子树信息的模板，写的还是比较优美的.

本地可过，bzoj 时限太紧，一直 TLE

#include<bits/stdc++.h>
#define setIO(s) freopen(s".in","r",stdin) , freopen(s".out","w",stdout)
#define maxn 100002
#define inf 100000000
#define isrt(x) (!(ch[f[x]][0]==x||ch[f[x]][1]==x))
#define get(x) (ch[f[x]][1]==x)
#define lson ch[x][0]
#define rson ch[x][1]
using namespace std;
int n,Q;
multiset<int>S[maxn];
int ch[maxn][2],f[maxn],rev[maxn],sta[maxn],minv[maxn],mintot[maxn],minson[maxn],val[maxn];
void mark(int x)
{
    if(!x) return;
    swap(lson,rson),rev[x]^=1;
}
void pushup(int x)
{
    if(!x) return;
    minv[x]=mintot[x]=val[x],minson[x]=inf;
    minv[x]=min(minv[x],min(minv[lson],minv[rson]));
    minson[x]=min(min(minson[lson],minson[rson]),*S[x].begin());
    mintot[x]=min(minv[x], minson[x]);
}
void pushdown(int x)
{
    if(!x||!rev[x]) return;
    mark(lson),mark(rson),rev[x]^=1;
}
void rotate(int x)
{
    int old=f[x],fold=f[old],which=get(x);
    if(!isrt(old)) ch[fold][ch[fold][1]==old]=x;
    ch[old][which]=ch[x][which^1],f[ch[old][which]]=old;
    ch[x][which^1]=old,f[old]=x,f[x]=fold;
    pushup(old),pushup(x);
}
void splay(int x)
{
    int v=0,u=x,fa;
    for(sta[++v]=u;!isrt(u);u=f[u]) sta[++v]=f[u];
    while(v) pushdown(sta[v--]);
    for(u=f[u];(fa=f[x])!=u;rotate(x))
        if(f[fa]!=u)
            rotate(get(x)==get(fa)?fa:x);
}
void Access(int x)
{
    int t=0;
    while(x)
    {
        splay(x);
        if(rson) S[x].insert(mintot[rson]);
        if(t) S[x].erase(S[x].lower_bound(mintot[t]));
        rson=t,t=x,x=f[x];
    }
}
void makert(int x)
{
    Access(x),splay(x),mark(x);
}
void link(int x,int y)
{
    makert(x), f[x]=y, S[y].insert(mintot[x]);
}
int main()
{
    int i,j,root=0;
    //         setIO("input");
    scanf("%d%d",&n,&Q);
    mintot[0]=minv[0]=minson[0]=val[0]=inf;
    for(i=0;i<=n;++i) S[i].insert(inf);
    for(i=1;i<=n;++i)
    {
        int a;
        scanf("%d%d",&a,&val[i]);
        if(a==0) { root=i; makert(i); pushup(i); }
        else link(a,i);
    }
    makert(root);
    while(Q--)
    {
        char opt[3];
        int x,y;
        scanf("%s",opt);
        if(opt[0]=='V')
        {
            scanf("%d%d",&x,&y);
            Access(x), splay(x), val[x]=y, pushup(x);
        }
        if(opt[0]=='E')
        {
            scanf("%d",&root);
            makert(root);
        }
        if(opt[0]=='Q')
        {
            scanf("%d",&x);
            Access(x), splay(x);
            printf("%d\n",min(val[x], *S[x].begin()));
        }
    }
    return 0;
}