bzoj3779: 重组病毒 link-cut-tree

题目传送门

这道题看了做了个神转换.....推荐个博客给各位大爷看看吧神犇传送门

代码敲了半天....题目也读了半天 线段树维护的东西很容易和lct混在一起 调了调能过也是很开心啊 运气比较好吧233

#include<cstdio>
#include<cstring>
#include<algorithm>
#define LL long long
using namespace std;
const int M=<<;
int read(){
    int ans=,f=,c=getchar();
    while(c<''||c>''){if(c=='-') f=-; c=getchar();}
    while(c>=''&&c<=''){ans=ans*+(c-''); c=getchar();}
    return ans*f;
}
int n,m,rt;
int next[M],sum,father[M],deep[M],first[M],second[M];
struct Edge{int u,v,from;}e[*M];
void ins(int a,int b){sum++; e[sum].u=a; e[sum].v=b; e[sum].from=next[a]; next[a]=sum;}
void insert(int a,int b){ins(a,b); ins(b,a);}
struct node{int l,r; LL sum,tag;}tr[M*];
int c[M][],fa[M],dfsum,rev[M];
void build(int x,int l,int r){
    tr[x].l=l; tr[x].r=r;
    if(l==r) return ;
    int mid=(l+r)>>;
    build(x<<,l,mid); build(x<<^,mid+,r);
}
void cal(int x,int w){tr[x].sum+=1LL*(tr[x].r-tr[x].l+)*w;}
void push_up(int x){tr[x].sum=tr[x<<].sum+tr[x<<^].sum;}
void push_down(int x){
    if(!tr[x].tag) return ;
    int w=tr[x].tag; tr[x].tag=;
    int l=x<<,r=x<<^;
    tr[l].tag+=w; cal(l,w);
    tr[r].tag+=w; cal(r,w);
}
void push_add(int x,int L,int R,int w){
    if(L>R) return ;
    if(L<=tr[x].l&&tr[x].r<=R){
        cal(x,w);
        tr[x].tag+=1LL*w; return ;
    }
    if(tr[x].l==tr[x].r) return ;
    push_down(x);
    int mid=(tr[x].l+tr[x].r)>>;
    if(L<=mid) push_add(x<<,L,R,w);
    if(R>mid) push_add(x<<^,L,R,w);
    push_up(x);
}
LL push_ans(int x,int L,int R){
    if(L>R) return ;
    if(L<=tr[x].l&&tr[x].r<=R) return tr[x].sum;
    //if(tr[x].l==tr[x].r) return 0;
    LL ans=; push_down(x);
    int mid=(tr[x].l+tr[x].r)>>;
    if(L<=mid) ans+=push_ans(x<<,L,R);
    if(R>mid) ans+=push_ans(x<<^,L,R);
    return ans;
}
void dfs(int x,int old){
    father[x]=fa[x]=old;
    first[x]=++dfsum;
    deep[x]=deep[old]+;
    push_add(,first[x],first[x],deep[x]);
    for(int i=next[x];i;i=e[i].from) if(e[i].v!=old) dfs(e[i].v,x);
    second[x]=dfsum;
}
bool isrt(int x){return !x||(c[fa[x]][]!=x&&c[fa[x]][]!=x);}//0也算
void down(int x){
    if(!rev[x]) return ;
    rev[x]=;
    int l=c[x][],r=c[x][];
    if(l) swap(c[l][],c[l][]),rev[l]^=;
    if(r) swap(c[r][],c[r][]),rev[r]^=;
}
void rotate(int x){
    int y=fa[x],z=fa[y],l=,r=;
    if(c[y][]==x) l=,r=;
    if(!isrt(y)) c[z][c[z][]==y]=x;
    fa[y]=x; fa[x]=z; fa[c[x][r]]=y;
    c[y][l]=c[x][r]; c[x][r]=y;
}
int st[M],top;
void splay(int x){
    st[++top]=x; for(int i=x;!isrt(i);i=fa[i])  st[++top]=fa[i];
    while(top) down(st[top--]);
    while(!isrt(x)){
        int y=fa[x],z=fa[y];
        if(!isrt(y)){
            if(c[z][]==y^c[y][]==x) rotate(x);
            else rotate(y);
        }
        rotate(x);
    }
}
bool inson(int x,int y){return first[x]<=first[y]&&second[y]<=second[x];}
int wson(int x,int y){
    for(int i=next[x];i;i=e[i].from) if(e[i].v!=father[x])
        if(first[e[i].v]<=first[y]&&second[y]<=second[e[i].v]) return e[i].v;
    return ;
}
void add(int x,int w){
    if(x==rt) push_add(,,n,w);
    else if(inson(x,rt)){
        int p=wson(x,rt);
        push_add(,,first[p]-,w);
        push_add(,second[p]+,n,w);
    }
    else push_add(,first[x],second[x],w);
}
int find(int x){
    while(c[x][]) down(x),x=c[x][];
    return x;
}
void acs(int x){
    int y=;
    while(x){
        splay(x);
        if(c[x][]) add(find(c[x][]),);
        if(y) add(find(y),-);
        c[x][]=y; y=x; x=fa[x];
    }
}
double addup(int x){
    if(x==rt) return (double)push_ans(,,n)/n;
    if(inson(x,rt)){
        int p=wson(x,rt);
        return ((double)push_ans(,,first[p]-)+(double)push_ans(,second[p]+,n))/(n-(second[p]-first[p]+));
    }
    else return (double)push_ans(,first[x],second[x])/(second[x]-first[x]+);
}
void mrt(int x){splay(x); rt=x; swap(c[x][],c[x][]); rev[x]^=;}
int main()
{
    int x,y;
    n=read(); m=read();
    for(int i=;i<n;i++) x=read(),y=read(),insert(x,y);
    rt=; build(,,n); dfs(,);
    char ch[];
    for(int i=;i<=m;i++){
        scanf("%s",ch); x=read();
        if(ch[]=='Q') printf("%.10lf\n",addup(x));
        else{
            acs(x);
            if(ch[]=='C') mrt(x);
        }
    }
    return ;
}