poj 3237

树链剖分模板题

 

//#include<bits/stdc++.h>
#include<iostream>
#include<cstring>
#include<cstdio>
using namespace std;
#define MAXN 100010
#define maxint (1<<30)
struct Edge{
    int to,next;
}edge[MAXN<<1];
int n,tot=0,last[MAXN]={};
void add_edge(int a,int b){
    ++tot;
    edge[tot].to=b;
    edge[tot].next=last[a];
    last[a]=tot;
}
int fa[MAXN],dep[MAXN],num[MAXN],son[MAXN];
void dfs(int x,int v,int d){
    fa[x]=v;
    dep[x]=d;
    num[x]=1;
    for(int i=last[x];i;i=edge[i].next)
        if(edge[i].to!=v){
            dfs(edge[i].to,x,d+1);
            num[x]+=num[edge[i].to];
            if(!son[x]||num[edge[i].to]>num[son[x]])
                son[x]=edge[i].to;
        }
}
int pos=0,top[MAXN],tree[MAXN],id[MAXN];
void dfs_(int x,int v){
    top[x]=v;
    tree[x]=pos;
    id[pos++]=x;
    if(!son[x])
        return;
    dfs_(son[x],v);
    for(int i=last[x];i;i=edge[i].next)
        if(edge[i].to!=son[x]&&edge[i].to!=fa[x])
            dfs_(edge[i].to,edge[i].to);
}

struct Node{
    int max,min,tag;
}a[MAXN*3]={};
void pushdown(int x,int l,int r){
    if(l==r)
        return;
    a[x].tag=0;
    
    a[x<<1].max=-a[x<<1].max;
    a[x<<1].min=-a[x<<1].min;
    swap(a[x<<1].max,a[x<<1].min);
    a[x<<1].tag^=1;
    
    a[(x<<1)|1].max=-a[(x<<1)|1].max;
    a[(x<<1)|1].min=-a[(x<<1)|1].min;
    swap(a[(x<<1)|1].max,a[(x<<1)|1].min);
    a[(x<<1)|1].tag^=1;
}
void change(int x,int l,int r,int k,int v){
    if(l==r&&l==k){
        a[x].max=a[x].min=v;
        a[x].tag=0;
        return;
    }
    int mid=(l+r)>>1;
    if(a[x].tag)
        pushdown(x,l,r);
    if(k<=mid)
        change(x<<1,l,mid,k,v);
    else
        change((x<<1)|1,mid+1,r,k,v);
    a[x].max=max(a[x<<1].max,a[(x<<1)|1].max);
    a[x].min=min(a[x<<1].min,a[(x<<1)|1].min);
}
void ne_update(int x,int l,int r,int ql,int qr){
    if(ql>r||qr<l)
        return;
    if(ql<=l&&r<=qr){
        a[x].tag^=1;
        a[x].max=-a[x].max;
        a[x].min=-a[x].min;
        swap(a[x].max,a[x].min);
        return;
    }
    int mid=(l+r)>>1;
    if(a[x].tag)
        pushdown(x,l,r);
    ne_update(x<<1,l,mid,ql,qr);
    ne_update((x<<1)|1,mid+1,r,ql,qr);
    a[x].max=max(a[x<<1].max,a[(x<<1)|1].max);
    a[x].min=min(a[x<<1].min,a[(x<<1)|1].min);
}
int query(int x,int l,int r,int ql,int qr){
    if(ql>r||qr<l)
        return -maxint;
    if(ql<=l&&r<=qr)
        return a[x].max;
    int mid=(l+r)>>1;
    if(a[x].tag)
        pushdown(x,l,r);
    return max(query(x<<1,l,mid,ql,qr),query((x<<1)|1,mid+1,r,ql,qr));    
}
int findmax(int u,int v){
    int res=-maxint;
    while(top[u]!=top[v]){
        if(dep[top[u]]>dep[top[v]])
            res=max(res,query(1,1,n,tree[top[u]],tree[u])),u=fa[top[u]];
        else
            res=max(res,query(1,1,n,tree[top[v]],tree[v])),v=fa[top[v]];
    }
    if(dep[u]>dep[v])
        swap(u,v);
    res=max(res,query(1,1,n,tree[son[u]],tree[v]));
    return res;
}
void Negate(int u,int v){
    while(top[u]!=top[v]){
        if(dep[top[u]]>dep[top[v]])
            ne_update(1,1,n,tree[top[u]],tree[u]),u=fa[top[u]];
        else
            ne_update(1,1,n,tree[top[v]],tree[v]),v=fa[top[v]];
    }
    if(dep[u]>dep[v])
        swap(u,v);
    ne_update(1,1,n,tree[son[u]],tree[v]);
}
void init(){
    tot=pos=0;
    memset(last,0,sizeof(last));
    memset(son,0,sizeof(son));
    memset(a,0,sizeof(a));
}
int main(){
    int t,a[MAXN],b[MAXN],c[MAXN];
    for(scanf("%d",&t);t;t--){
        scanf("%d",&n);    n--;
        init();
        for(int i=1;i<=n;i++){
            scanf("%d%d%d",&a[i],&b[i],&c[i]);
            add_edge(a[i],b[i]);
            add_edge(b[i],a[i]);
        }
        dfs(1,0,0);
        dfs_(1,1);
        for(int i=1;i<=n;i++){
            if(dep[a[i]]>dep[b[i]])
                swap(a[i],b[i]);
            change(1,1,n,tree[b[i]],c[i]);
        }
        char op[10];
        while(~scanf("%s",op)){
            if(op[0]=='D')
                break;
            int u,v;
            scanf("%d%d",&u,&v);
            if(op[0]=='Q')
                printf("%d\n",findmax(u,v));
            if(op[0]=='C')
                change(1,1,n,tree[b[u]],v);
            if(op[0]=='N')
                Negate(u,v);
        }
    }
    return 0;
}