BZOJ 4771: 七彩树 可持久化线段树+树链的并

这个思路挺有意思的 ~     

利用树链的并来保证每个颜色只贡献一次，然后用可持久化线段树维护 

code: 

#include <set>
#include <cstdio>
#include <cstring>   
#include <algorithm>     
#define N 100005   
#define setIO(s) freopen(s".in","r",stdin)  , freopen(s".out","w",stdout)    
using namespace std; 
namespace seg 
{   
    #define lson t[x].ls 
    #define rson t[x].rs 
    int tot;   
    struct node 
    {
        int ls,rs,sum; 
    }t[N*80];        
    void clr() 
    {
        for(int i=1;i<=tot;++i) t[i].ls=t[i].rs=t[i].sum=0; 
        tot=0;    
    }
    int newnode() 
    {
        return ++tot; 
    }
    void build(int &x,int l,int r) 
    {   
        x=newnode(); 
        if(l==r)   return; 
        int mid=(l+r)>>1;   
        if(l<=mid) build(lson,l,mid); 
        if(r>mid)  build(rson,mid+1,r);   
    }
    int cop(int x,int l,int r,int p,int v) 
    {
        int now=newnode(); 
        t[now]=t[x];   
        t[now].sum+=v;     
        if(l==r) return now; 
        int mid=(l+r)>>1;   
        if(p<=mid) t[now].ls=cop(lson,l,mid,p,v); 
        else t[now].rs=cop(rson,mid+1,r,p,v);    
        return now;      
    }
    int query(int x,int l,int r,int L,int R) 
    {   
        if(!x) return 0; 
        if(l>=L&&r<=R) return t[x].sum; 
        int re=0;  
        int mid=(l+r)>>1; 
        if(L<=mid) re+=query(lson,l,mid,L,R); 
        if(R>mid)  re+=query(rson,mid+1,r,L,R); 
        return re; 
    }       
    #undef lson 
    #undef rson 
};  
set<int>se[N];   
set<int>::iterator fr,ba;     
int edges,n,m,tim,ct;        
int hd[N],to[N],nex[N],col[N],nod[N],st[N],ed[N];           
int fa[N],dfn[N],dep[N],size[N],son[N],top[N];       
int id[N],rt[N];   
bool cmp(int a,int b) 
{
    return dep[a]<dep[b];   
}
void add(int u,int v) 
{
    nex[++edges]=hd[u],hd[u]=edges,to[edges]=v;  
} 
void dfs1(int u,int ff) 
{     
    size[u]=1;   
    dfn[u]=++tim; 
    st[u]=dfn[u];    
    nod[dfn[u]]=u;     
    dep[u]=dep[ff]+1;   
    for(int i=hd[u];i;i=nex[i]) 
    {
        int v=to[i];  
        dfs1(v,u);   
        size[u]+=size[v];  
        if(size[v]>size[son[u]])  son[u]=v;   
    }
    ed[u]=tim;   
}
void dfs2(int u,int tp) 
{
    top[u]=tp; 
    if(son[u])   dfs2(son[u],tp); 
    for(int i=hd[u];i;i=nex[i]) 
    { 
        if(to[i]!=son[u]) 
        {
            dfs2(to[i],to[i]);   
        }
    }
}
int LCA(int x,int y) 
{
    while(top[x]!=top[y]) 
    {
        dep[top[x]]>dep[top[y]]?x=fa[top[x]]:y=fa[top[y]]; 
    } 
    return dep[x]<dep[y]?x:y;   
}
void solve() 
{    
    int i,j,last=0; 
    scanf("%d%d",&n,&m);               
    for(i=1;i<=n;++i)  scanf("%d",&col[i]); 
    for(i=2;i<=n;++i)  
    {
        scanf("%d",&fa[i]); 
        add(fa[i],i);          
    }
    dfs1(1,0);   
    dfs2(1,1);           
    for(i=1;i<=n;++i)   id[i]=i;  
    sort(id+1,id+1+n,cmp);         
    int lst=0;   
    seg::build(rt[0],1,n);   
    for(i=1;i<=n;++i) 
    {               
        int p=id[i]; 
        int c=col[p];             
        while(dep[p]>lst)  rt[lst+1]=rt[lst],++lst;                  
        se[c].insert(dfn[p]);   
        fr=ba=se[c].lower_bound(dfn[p]),ba++;            
        if(fr!=se[c].begin()) 
        {  
            --fr;   
            rt[lst]=seg::cop(rt[lst],1,n,dfn[LCA(nod[*fr],p)],-1);   
            ++fr;    
        }
        if(ba!=se[c].end()) 
        {
            rt[lst]=seg::cop(rt[lst],1,n,dfn[LCA(nod[*ba],p)],-1);  
        }
        if(fr!=se[c].begin()&&ba!=se[c].end()) 
        {
            --fr;     
            rt[lst]=seg::cop(rt[lst],1,n,dfn[LCA(nod[*fr],nod[*ba])],1);    
        }                   
        rt[lst]=seg::cop(rt[lst],1,n,dfn[p],1);             
    }    
    for(i=1;i<=m;++i) 
    {
        int x,d; 
        scanf("%d%d",&x,&d);     
        x^=last,d^=last;        
        last=seg::query(rt[min(n,dep[x]+d)],1,n,st[x],ed[x]);  
        printf("%d
",last);           
    }       
    for(i=1;i<=n;++i)  son[i]=0;  
    for(i=1;i<=n;++i)  hd[i]=0; 
    for(i=1;i<=edges;++i) nex[i]=to[i]=0;     
    edges=tim=0; 
    seg::clr(); 
    for(i=1;i<=n;++i)  se[i].clear();        
}
int main() 
{ 
    // setIO("input"); 
    int i,j,T; 
    scanf("%d",&T); 
    while(T--)  solve();  
    return 0; 
}