hdu 3966 树链剖分第3遍

#include<cstdio>
#include<cstring>
#pragma comment(linker, "/STACK:1024000000,1024000000")
#include<iostream>
#include<algorithm>
using namespace std;
const int M = 50100;
int son[M],top[M],father[M],dep[M],ti[M],siz[M];
int idx,tp,n;
struct {
    int head;
}H[M];
struct {
    int v,next;
}E[M];
void dfs_1(int u,int fa){
    son[u] = 0;siz[u] = 1;father[u] = fa;dep[u] = dep[fa] + 1;
    for(int i=H[u].head;i!=-1;i=E[i].next){
        int v = E[i].v;
        if(v == fa)continue;
        dfs_1(v,u);
        siz[u] += siz[v];
        if(siz[son[u]] < siz[v])son[u] = v;
    }
}
void dfs_2(int u,int fa){
    top[u] = fa;
    ti[u] = idx++;
    if(son[u]) dfs_2(son[u],fa);
    for(int i=H[u].head;i!=-1;i=E[i].next){
        int v = E[i].v;
        if(v == father[u]|| v == son[u])continue;
        dfs_2(v,v);
    }
}
int lobit(int x){
    return x&(-x);
}
int num[M*2];
void update(int x ,int d){
    while( x <= n){
        num[x] += d;
        x += lobit(x);
    }
}
void change(int u,int v,int w){
    int f1 = top[u];
    int f2 = top[v];
    while(f1 != f2){
        if(dep[f1] <dep[f2]){
            swap(f1,f2);
            swap(u,v);
        }
        update(ti[f1],w);
        update(ti[u]+1,-w);
        u = father[f1];f1 = top[u];
    }
    if(dep[u] > dep[v])swap(u,v);
    update(ti[u],w);
    update(ti[v]+1,-w);
}
int sum(int x){
    int ans = 0;
    while(x>0){
        ans += num[x];
        x -= lobit(x);
    }
    return ans;
}

void add(int u,int v){
    E[tp].v = v;
    E[tp].next = H[u].head;
    H[u].head = tp++;
}
void init(){
    memset(E,-1,sizeof(E));
    memset(H,-1,sizeof(H));
    memset(num,0,sizeof(num));
    tp = 0;
    idx = 1;
}
int findp(int x){
    return sum(ti[x]);
}
int a[M];
int main(){
   // freopen("input.txt","r",stdin);
    int m,p,u,v,w;
    while(scanf("%d%d%d",&n,&m,&p)==3){
    init();
        for(int i=1;i<=n;i++){
            scanf("%d",&a[i]);
        }
        while(m -- ){
            scanf("%d%d",&u,&v);
            add(u,v);add(v,u);
        }
        dfs_1(1,1);
        dfs_2(1,1);
        for(int i=1;i<=n;i++){
           update(ti[i],a[i]);
           update(ti[i]+1,-a[i]);
        }

        char op[100];
        while (p--){
            scanf("%s%d",op,&u);
            if(op[0] == 'Q'){
                printf("%d\n",sum(ti[u]));
            }else {
                scanf("%d%d",&v,&w);
                if(op[0] == 'D')w = -w;
                change(u,v,w);
            }
        }

    }
}