bzoj3551: [ONTAK2010]Peaks加强版

很明显只有最小生成树里面的点有用

我会一个离线的做法，把询问边长排序，逐步合并树，启发式合并splay

在线怎么做呢？

考虑合并出最小生成树的过程，两点合并是并不是一边连向一边而是建出新点，并将新点连向两边边权为这两点的边权。重构出新树后，所有原点都是叶子节点，并且边权深到浅单增，可以用倍增找到断开的位置，问题变成求子树中第k大的值，上一个主席树就好了

码力堪忧

#include<cstdio>
#include<iostream>
#include<cstring>
#include<cstdlib>
#include<algorithm>
#include<cmath>
using namespace std;
const int _=1e2;
const int maxn=1e5+_;
const int maxp=2*maxn;
const int maxm=5e5+_;
const int maxQ=5e5+_;
int n,m,Q,w[maxn]; int lslen,ls[maxn];
inline int read()
{
    int x=0,f=1;char ch=getchar();
    while(!isdigit(ch))ch=getchar();
    while(isdigit(ch)){x=x*10+ch-'0';ch=getchar();}
    return x*f;
}
inline void write(int d)
{
    if(d>=10)write(d/10);
    putchar(d%10+'0');
}

namespace CHAIR
{
    struct trnode
    {
        int lc,rc,c;
    }tr[12*maxp];int trlen,rt[maxp];
    int maketree(int now,int l,int r,int p)
    {
        if(now==0)now=++trlen;
        tr[now].c++;
        if(l!=r)
        {
            int mid=(l+r)/2;
            if(p<=mid)tr[now].lc=maketree(tr[now].lc,l,mid,p);
            else tr[now].rc=maketree(tr[now].rc,mid+1,r,p);
        }
        return now;
    }
    int merge(int x,int y)
    {
        if(x==0||y==0)return x+y;
        tr[x].c+=tr[y].c;
        tr[x].lc=merge(tr[x].lc,tr[y].lc);
        tr[x].rc=merge(tr[x].rc,tr[y].rc);
        return x;
    }
    int findkth(int x,int y,int l,int r,int k)
    {
        if(tr[y].c-tr[x].c<k)return -1;
        if(l==r)return l;
        int mid=(l+r)/2;
        int c=tr[tr[y].rc].c-tr[tr[x].rc].c;
        if(c>=k)return findkth(tr[x].rc,tr[y].rc,mid+1,r,k);
        else return findkth(tr[x].lc,tr[y].lc,l,mid,k-c);
    }
}

struct node
{
    int x,y,d,next;
}a[maxp];int len,last[maxp];
void ins(int x,int y,int d)
{
    len++;
    a[len].x=x;a[len].y=y;a[len].d=d;
    a[len].next=last[x];last[x]=len;
//    printf("%d %d %d
",x,y,d);
}
int z,L[maxp],R[maxp],de[maxp];
int dep[maxp],f[30][maxp];
void dfs(int x)
{
    for(int i=1;(1<<i)<=dep[x];i++)f[i][x]=f[i-1][f[i-1][x]];
    L[x]=++z;
    if(last[x]==0)
    {
        CHAIR::rt[z]=CHAIR::maketree(CHAIR::rt[z],1,lslen,w[x]);
        CHAIR::rt[z]=CHAIR::merge(CHAIR::rt[z],CHAIR::rt[z-1]);
    }
    else CHAIR::rt[z]=CHAIR::rt[z-1];
    for(int k=last[x];k;k=a[k].next)
    {
        int y=a[k].y; de[y]=a[k].d;
        f[0][y]=x;
        dep[y]=dep[x]+1;
        dfs(y);
    }
    R[x]=z;
}

int fa[maxp];
int findfa(int x)
{
    if(fa[x]==x)return x;
    fa[x]=findfa(fa[x]);return fa[x];
}
struct edge{int x,y,d;}e[maxm];
bool cmp(edge e1,edge e2){return e1.d<e2.d;}
int main()
{
    freopen("a.in","r",stdin);
    freopen("a.out","w",stdout);
    n=read(),m=read(),Q=read();
    for(int i=1;i<=n;i++)
        w[i]=read(),ls[++lslen]=w[i];
        
    sort(ls+1,ls+lslen+1);
    lslen=unique(ls+1,ls+lslen+1)-ls-1;
    for(int i=1;i<=n;i++)
        w[i]=lower_bound(ls+1,ls+lslen+1,w[i])-ls;
        
    for(int i=1;i<=m;i++)
        e[i].x=read(),e[i].y=read(),e[i].d=read();
    sort(e+1,e+m+1,cmp);
    
    int fx,fy;
    for(int i=1;i<=2*n;i++)fa[i]=i;
    for(int i=1;i<=m;i++)
    {
        fx=findfa(e[i].x),fy=findfa(e[i].y);
        if(fx!=fy)
        {
            n++; fa[fx]=n,fa[fy]=n;
            ins(n,fx,e[i].d);
            ins(n,fy,e[i].d);
        }
    }
    dfs(n);
    
    int x,k,d,lastans=0;
    while(Q--)
    {
        x=read(),d=read(),k=read();
        x^=lastans,k^=lastans,d^=lastans;
        if(de[x]>d)
        {
            if(k==1)lastans=w[x],printf("%d
",w[x]);
            else puts("-1"),lastans=0;
            continue;
        }
        for(int i=25;i>=0;i--)
            if((1<<i)<dep[x]&&de[f[i][x]]<=d)x=f[i][x];
        x=f[0][x];
        lastans=CHAIR::findkth(CHAIR::rt[L[x]-1],CHAIR::rt[R[x]],1,lslen,k);
        if(lastans!=-1)
        {
            lastans=ls[lastans];
            write(lastans),putchar('
');
        }
        else puts("-1"),lastans=0;
    }
    
    return 0;
}