树链剖分——模板题hdu3966

#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define maxn 50005
struct Edge{int to,nxt;}edge[maxn<<1];
int head[maxn],tot,n,m,q,v[maxn];
void init(){memset(head,-1,sizeof head);tot=0;}
void addedge(int u,int v){edge[tot].to=v;edge[tot].nxt=head[u];head[u]=tot++;}

int f[maxn],size[maxn],d[maxn],son[maxn];
void dfs1(int x,int pre,int deep){
    size[x]=1;d[x]=deep;f[x]=pre;
    for(int i=head[x];i!=-1;i=edge[i].nxt){
        int y=edge[i].to;
        if(y==pre)continue;
        dfs1(y,x,deep+1);
        size[x]+=size[y];
        if(size[y]>size[son[x]])son[x]=y;
    }
}
int top[maxn],id[maxn],rk[maxn],cnt;
void dfs2(int x,int tp){
    top[x]=tp;id[x]=++cnt;rk[cnt]=x;
    if(son[x])dfs2(son[x],tp);
    for(int i=head[x];i!=-1;i=edge[i].nxt){
        int y=edge[i].to;
        if(y!=son[x] && y!=f[x])dfs2(y,y);
    }
}

#define lson l,m,rt<<1
#define rson m+1,r,rt<<1|1
int lazy[maxn<<2];
void pushdown(int rt){
    if(lazy[rt]){
        lazy[rt<<1]+=lazy[rt];lazy[rt<<1|1]+=lazy[rt];
        lazy[rt]=0;
    }
}
void update(int L,int R,int l,int r,int rt,int c){
    if(L<=l && R>=r){lazy[rt]+=c;return;}
    int m=l+r>>1;
    pushdown(rt);
    if(L<=m)update(L,R,lson,c);
    if(R>m)update(L,R,rson,c);
}
int query(int pos,int l,int r,int rt){
    if(l==r)return lazy[rt]+v[rk[l]];
    pushdown(rt);
    int m=l+r>>1;
    if(pos<=m)return query(pos,lson);
    else return query(pos,rson);
}

void Update(int x,int y,int c){
    while(top[x]!=top[y]){
        if(d[top[x]]<d[top[y]])swap(x,y);
        update(id[top[x]],id[x],1,n,1,c);
        x=f[top[x]];
    }
    if(id[x]>id[y])swap(x,y);
    update(id[x],id[y],1,n,1,c);
}

int main(){
    while(scanf("%d%d%d",&n,&m,&q)==3){
        init();int x,y,z;char op[2];
        for(int i=1;i<=n;i++)scanf("%d",&v[i]);
        for(int i=1;i<n;i++){scanf("%d%d",&x,&y);addedge(x,y);addedge(y,x);}
        
        memset(son,0,sizeof son);memset(f,0,sizeof f);
        cnt=0;dfs1(1,0,1);dfs2(1,1);
        memset(lazy,0,sizeof lazy);
        while(q--){
            scanf("%s",&op);
            if(op[0]=='I'){scanf("%d%d%d",&x,&y,&z);Update(x,y,z);}
            if(op[0]=='D'){scanf("%d%d%d",&x,&y,&z);Update(x,y,-z);}
            if(op[0]=='Q'){scanf("%d",&x);cout<<query(id[x],1,n,1)<<'\n';}
        }
    }
    return 0;
}