BZOJ 3639: Query on a tree VII LCT_set维护子树信息

用 set 维护子树信息，细节较多。

Code:

#include <cstring>
#include <cstdio>
#include <algorithm>
#include <set>
#include <string>
#define setIO(s) freopen(s".in","r",stdin), freopen(s".out","w",stdout)
#define maxn 100009
#define inf -2147483647
using namespace std;
int fat[maxn];
int n,m;
struct Graph{
    int head[maxn],to[maxn<<1],nex[maxn<<1],cnt;
    void addedge(int u,int v){ nex[++cnt]=head[u],head[u]=cnt,to[cnt]=v; }
    void dfs(int u,int father){
        fat[u]=father;
        for(int v=head[u];v;v=nex[v]) if(to[v]!=father) dfs(to[v],u);
    }
    void Build(){
        for(int i=1;i<n;++i){
            int a,b;
            scanf("%d%d",&a,&b), addedge(a,b),addedge(b,a);
        }
        dfs(1,0);
    }
}G;
int col[maxn],v[maxn];
struct LCT{
	multiset<int>s[maxn];
    multiset<int>::reverse_iterator rit;
    int ch[maxn][2],f[maxn];
    int siz[maxn],mx[maxn];
    void init(){ mx[0]=-2147483647; }
    int value(int x) { rit=s[x].rbegin(); return (*rit);  }
    int get(int x){ return ch[f[x]][1]==x; }
    int lson(int x){ return ch[x][0];}
    int rson(int x){ return ch[x][1];}
    int isRoot(int x){ return !(ch[f[x]][0]==x||ch[f[x]][1]==x); }
    void pushup(int x){
    	if(!x) return;
    	mx[x]=max(v[x],max(mx[lson(x)],mx[rson(x)]));
    	if(!s[x].empty()) mx[x]=max(mx[x],value(x));
    }
    void rotate(int x)
    {
        int old=f[x],oldf=f[old],which=get(x);
        if(!isRoot(old)) ch[oldf][ch[oldf][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]=oldf;
        pushup(old),pushup(x);
    }
    void splay(int x)
    {
        int u=x;
        while(!isRoot(u)) u=f[u];
        u=f[u];
        for(int fa;(fa=f[x])!=u;rotate(x))
            if(f[fa]!=u) rotate(get(fa)==get(x)?fa:x);
    }
    void Access(int x){
        for(int y=0;x;y=x,x=f[x]){
            splay(x);
            if(rson(x)) s[x].insert(mx[rson(x)]);
            if(ch[x][1]=y) s[x].erase(s[x].find(mx[y])) ;
            pushup(x);
        }
    }
    void cut(int a,int b){
        if(!a) return;
        Access(b),splay(b),ch[b][0]=f[ch[b][0]]=0,pushup(b);
    }
    void link(int a,int b)
    {
        if(!a) return;
        Access(a),splay(a),Access(b),splay(b);
        f[b]=a,ch[a][1]=b,pushup(a);
    }
    int findRoot(int a){
        Access(a),splay(a);
        while(ch[a][0]) a=ch[a][0];
        return a;
    }
}tree[2];
int main(){
    //setIO("debug");
    scanf("%d",&n),G.Build(),tree[0].init(),tree[1].init();
    for(int i=1;i<=n;++i) scanf("%d",&col[i]);
    for(int i=1;i<=n;++i) scanf("%d",&v[i]);
    fat[1]=n+1,v[n+1]=tree[1].mx[n+1]=tree[0].mx[n+1]=inf;
    for(int i=1;i<=n;++i) tree[col[i]].link(fat[i],i);
    int opt,a;
    scanf("%d",&m);
    for(int i=1;i<=m;++i){
        scanf("%d%d",&opt,&a);
        if(opt==0) {
            int x=tree[col[a]].findRoot(a);
            tree[col[a]].splay(x);
            if(col[x]==col[a]) printf("%d\n",tree[col[a]].mx[x]);
            else printf("%d\n",tree[col[a]].mx[tree[col[a]].ch[x][1]]);
        }
        if(opt==1) {
            tree[col[a]].cut(fat[a],a),col[a]^=1,tree[col[a]].link(fat[a],a);
        }
        if(opt==2)
        {
        	tree[col[a]].Access(a),tree[col[a]].splay(a);
            scanf("%d",&v[a]);
        	tree[col[a]].pushup(a);
        }
    }
    return 0;
}