LUOGU P3178 [HAOI2015]树上操作

传送门

解题思路

树链剖分裸题，线段树维护。

代码

#include<iostream>
#include<cstdio>
#include<cstring>
#define int long long

using namespace std;
const int MAXN = 100005;

inline int rd(){
    int x=0,f=1;char ch=getchar();
    while(!isdigit(ch)) {f=ch=='-'?0:1;ch=getchar();}
    while(isdigit(ch))  {x=(x<<1)+(x<<3)+ch-'0';ch=getchar();}
    return f?x:-x;
}

int n,m,a[MAXN],sum[MAXN<<2],lazy[MAXN<<2];
int w[MAXN],id[MAXN],fa[MAXN],dep[MAXN],son[MAXN],siz[MAXN],top[MAXN];
int num,head[MAXN],cnt,to[MAXN<<1],nxt[MAXN<<1];

inline void add(int bg,int ed){
    to[++cnt]=ed,nxt[cnt]=head[bg],head[bg]=cnt;
}

void dfs1(int x,int f,int d){
    dep[x]=d,fa[x]=f,siz[x]=1;
    int maxson=-1;
    for(register int i=head[x];i;i=nxt[i]){
        int u=to[i];if(u==f) continue;
        dfs1(u,x,d+1);
        siz[x]+=siz[u];
        if(siz[u]>maxson) {maxson=siz[u];son[x]=u;}
    }
}

void dfs2(int x,int topf){
    id[x]=++num,w[num]=a[x],top[x]=topf;
    if(!son[x]) return;
    dfs2(son[x],topf);
    for(register int i=head[x];i;i=nxt[i]){
        int u=to[i];if(u==fa[x] || u==son[x]) continue;
        dfs2(u,u);
    }
}

//----------------------xds------------------------

inline void pushdown(int x,int ln,int rn){
    sum[x<<1]+=ln*lazy[x],sum[x<<1|1]+=rn*lazy[x];
    lazy[x<<1]+=lazy[x],lazy[x<<1|1]+=lazy[x];
    lazy[x]=0;
}

void build(int x,int l,int r){
    if(l==r){
        sum[x]=w[l];
        return;
    }
    int mid=l+r>>1;
    build(x<<1,l,mid);
    build(x<<1|1,mid+1,r);
    sum[x]=sum[x<<1]+sum[x<<1|1];
}

void update(int x,int l,int r,int L,int R,int k){
    if(L<=l && r<=R){
        sum[x]+=(r-l+1)*k;
        lazy[x]+=k;
        return;
    }
    int mid=l+r>>1;
    if(lazy[x]) pushdown(x,mid-l+1,r-mid);
    if(mid>=L) update(x<<1,l,mid,L,R,k);
    if(mid<R)  update(x<<1|1,mid+1,r,L,R,k);
    sum[x]=sum[x<<1]+sum[x<<1|1];  
}

int query(int x,int l,int r,int L,int R){
    if(L<=l && r<=R) return sum[x];
    int mid=l+r>>1,ret=0;
    if(lazy[x]) pushdown(x,mid-l+1,r-mid);
    if(mid>=L) ret+=query(x<<1,l,mid,L,R);
    if(mid<R)  ret+=query(x<<1|1,mid+1,r,L,R);
    return ret;
}

int qSon(int x){
    int ret=0;
    while(top[x]!=1){
        ret+=query(1,1,n,id[top[x]],id[x]);
        x=fa[top[x]];
    }
    ret+=query(1,1,n,1,id[x]);
    return ret;
}

signed main(){
    n=rd(),m=rd();
    for(register int i=1;i<=n;i++) a[i]=rd();
    int op,x,y,z;
    for(register int i=1;i<n;i++){
        x=rd(),y=rd();
        add(x,y),add(y,x);
    }
    dfs1(1,0,1),dfs2(1,1);
//  for(register int i=1;i<=n;i++) cout<<id[i]<<" ";cout<<endl;
    build(1,1,n);
    while(m--){
        op=rd();
        if(op==1){
            x=rd(),z=rd();
            update(1,1,n,id[x],id[x],z);
        }
        else if(op==2){
            x=rd(),z=rd();
            update(1,1,n,id[x],id[x]+siz[x]-1,z);
        }
        else {
            int x=rd();
            printf("%lld
",qSon(x));
        }
    }
    return 0;
}