【模板】树链剖分

#include<bits/stdc++.h>
using namespace std;
const int N=2e5+8;
int modd,n,m,rt,cnt=0,cnto=0;
int son[N],id[N],top[N],f[N],dep[N],siz[N],h[N<<1],w[N],wt[N];
struct edge{
    int to,nex;
}e[N];
struct tree{
    int sum,lazy;
}tr[N<<2];
void add(int x,int y){
    e[++cnt]=(edge){y,h[x]};
    h[x]=cnt;
}
void dfs1(int u,int fa,int deep){
    dep[u]=deep;
    f[u]=fa;
    siz[u]=1;
    int maxson=-1;
    for(int i=h[u];i;i=e[i].nex){
        int v=e[i].to;
        if(v==fa) continue;
        dfs1(v,u,deep+1);
        siz[u]+=siz[v];
        if(siz[v]>maxson){
            son[u]=v;
            maxson=siz[v];
        }
    }
}
void dfs2(int u,int topfa){
    id[u]=++cnto;
    wt[cnto]=w[u];
    top[u]=topfa;
    if(!son[u]) return;
    dfs2(son[u],topfa);
    for(int i=h[u];i;i=e[i].nex){
        int v=e[i].to;
        if(v==f[u]||v==son[u]) continue;
        dfs2(v,v);
    }
}
//线段树下
void build(int o,int l,int r){
    if(l==r){
        tr[o].sum=wt[l];
        if(tr[o].sum>modd) tr[o].sum%=modd;
        return;
    }
    int m=(l+r)>>1;
    build(o<<1,l,m);
    build(o<<1|1,m+1,r);
    tr[o].sum=(tr[o<<1].sum+tr[o<<1|1].sum)%modd;
}
void push_down(int o,int len){
    tr[o<<1].lazy+=tr[o].lazy;
    tr[o<<1|1].lazy+=tr[o].lazy;
    tr[o<<1].sum+=tr[o].lazy*(len+1>>1);
    tr[o<<1|1].sum+=tr[o].lazy*(len>>1);
    if(tr[o<<1].sum>=modd) tr[o<<1].sum%=modd;
    if(tr[o<<1|1].sum>=modd) tr[o<<1|1].sum%=modd;
    tr[o].lazy=0;
}
int query(int o,int l,int r,int x,int y){
    if(x<=l && r<=y) return tr[o].sum%modd;
    if(tr[o].lazy) push_down(o,r-l+1);
    int m=(l+r)>>1;
    int ans=0;
    if(x<=m) ans+=query(o<<1,l,m,x,y);
    if(y>m) ans+=query(o<<1|1,m+1,r,x,y);
    return ans%modd;
}
void change(int o,int l,int r,int x,int y,int k){
    if(x<=l && r<=y){
        tr[o].lazy+=k;
        tr[o].sum+=k*(r-l+1);
        return;
    }
    int m=(l+r)>>1;
    if(tr[o].lazy) push_down(o,r-l+1);
    if(x<=m) change(o<<1,l,m,x,y,k);
    if(y>m) change(o<<1|1,m+1,r,x,y,k);
    tr[o].sum=(tr[o<<1].sum+tr[o<<1|1].sum)%modd;
}
//线段树上
//树链下
int qSon(int u){
    return query(1,1,n,id[u],id[u]+siz[u]-1);
}
int qRange(int u,int v){
    int ans=0;
    while(top[u]!=top[v]){
        if(dep[top[u]]<dep[top[v]]) swap(u,v);
        ans+=query(1,1,n,id[top[u]],id[u]);
        ans%=modd;
        u=f[top[u]];
    }
    if(dep[u]>dep[v]) swap(u,v);
    ans+=query(1,1,n,id[u],id[v]);
    return ans%modd;
}
void updSon(int u,int k){
    change(1,1,n,id[u],id[u]+siz[u]-1,k);
}
void updRange(int u,int v,int k){
    k%=modd;
    while(top[u]!=top[v]){
        if(dep[top[u]]<dep[top[v]]) swap(u,v);
        change(1,1,n,id[top[u]],id[u],k);
        u=f[top[u]];
    }
    if(dep[u]>dep[v]) swap(u,v);
    change(1,1,n,id[u],id[v],k);
}
//树链上
int main(){
    memset(h,0,sizeof(h));
    memset(son,0,sizeof(son));
    scanf("%d%d%d%d",&n,&m,&rt,&modd);
    for(int i=1;i<=n;++i) scanf("%d",&w[i]);
    for(int i=1;i<n;++i){
        int x,y;scanf("%d%d",&x,&y);
        add(x,y);add(y,x);
    }
    dfs1(rt,0,1);
    dfs2(rt,rt);
    build(1,1,n);
    while(m--){
        int op,x,y,z;
        scanf("%d",&op);
        if(op==1){
            scanf("%d%d%d",&x,&y,&z);
            updRange(x,y,z);
        }
        else if(op==2){
            scanf("%d%d",&x,&y);
            printf("%d\n",qRange(x,y));
        }
        else if(op==3){
            scanf("%d%d",&x,&y);
            updSon(x,y);
        }
        else if(op==4){
            scanf("%d",&x);
            printf("%d\n",qSon(x));
        }
    }
    return 0;
}