[模板] 树链剖分

讲真 sublime挺好用的。

//Stay foolish,stay hungry,stay young,stay simple
#include<iostream>
#include<cstdio>
#include<cctype>
#define ls now<<1
#define rs now<<1|1
#define int long long
using namespace std;

const int MAXN=100005;

inline int rd(){
    int ret=0,f=1;char c;
    while(c=getchar(),!isdigit(c))f=c=='-'?-1:1;
    while(isdigit(c))ret=ret*10+c-'0',c=getchar();
    return ret*f;
}

struct Edge{
    int next,to;
}e[MAXN<<1];
int ecnt,head[MAXN];
inline void add(int x,int y){
    e[++ecnt].next = head[x];
    e[ecnt].to = y;
    head[x] = ecnt;
}

int n,m,r,p;
int a[MAXN];
int w[MAXN];

struct Node{
    int val,lazy;
}node[MAXN<<2];

void pushup(int now){
    node[now].val = node[ls].val + node[rs].val ;
    return;
}

void pushdown(int now,int l,int r){
    node[ls].lazy +=node[now].lazy ;
    node[rs].lazy +=node[now].lazy ;    
    int mid=(l+r)>>1;
    node[ls].val +=node[now].lazy *(mid-l+1);
    node[rs].val +=node[now].lazy *(r-mid);
    node[now].lazy = 0;
}

void build(int l,int r,int now){
    if(l==r){
        node[now].val = a[l]%p;
        return;
    } 
    int mid=(l+r)>>1;
    build(l,mid,ls);
    build(mid+1,r,rs);
    pushup(now);
}

void updata(int L,int R,int l,int r,int now,int w){
    if(L<=l&&r<=R){
        node[now].lazy += w;
        node[now].val += w*(r-l+1);
        return;
    }
    pushdown(now,l,r);
    int mid=(l+r)>>1;
    if(L<=mid) updata(L,R,l,mid,ls,w);
    if(mid <R) updata(L,R,mid+1,r,rs,w);
    pushup(now);
}

int query(int L,int R,int l,int r,int now){
    if(L<=l&&r<=R){
        return node[now].val ;
    }
    pushdown(now,l,r);
    int mid=(l+r)>>1;
    int ret=0;
    if(L<=mid) ret+=query(L,R,l,mid,ls);
    if(mid <R) ret+=query(L,R,mid+1,r,rs);
    return ret;
}

int siz[MAXN],fa[MAXN],son[MAXN],dep[MAXN];
void dfs1(int x,int pre,int dp){
    siz[x]=1;fa[x]=pre,dep[x]=dp+1;
    int mx=-1;
    for(int i=head[x];i;i=e[i].next){
        int v=e[i].to;
        if(v==pre) continue;
        dfs1(v,x,dp+1);
        siz[x]+=siz[v];
        if(mx<siz[v]){
            son[x]=v;
            mx=siz[v];
        }
    }
}

int id[MAXN],top[MAXN],tim=0;
void dfs2(int x,int tp){
    top[x]=tp;id[x]=++tim;
    a[tim]=w[x];
    if(son[x]) dfs2(son[x],tp);
    for(int i=head[x];i;i=e[i].next){
        int v=e[i].to;
        if(v==fa[x]||v==son[x]) continue;
        dfs2(v,v);
    }
}

int query_link(int x,int y){
    int ans=0;
    while(top[x]!=top[y]){
        if(dep[top[x]]<dep[top[y]])swap(x,y);
        ans+=query(id[top[x]],id[x],1,n,1);
        ans%=p;
        x=fa[top[x]];
    }
    if(dep[x]>dep[y]) swap(x,y);
    ans+=query(id[x],id[y],1,n,1);
    ans%=p;
    return ans;
}

void updata_link(int x,int y,int k){
    k%=p;
    while(top[x]!=top[y]){
        if(dep[top[x]]<dep[top[y]])swap(x,y);
        updata(id[top[x]],id[x],1,n,1,k);
        x=fa[top[x]];
    }
    if(dep[x]>dep[y]) swap(x,y);
    updata(id[x],id[y],1,n,1,k);
}

int query_son(int x){
    return query(id[x],id[x]+siz[x]-1,1,n,1)%p;
}

void updata_son(int x,int w){
    w%=p;
    updata(id[x],id[x]+siz[x]-1,1,n,1,w);
}

signed main(){
//  freopen("test.txt","w",stdout);
    n=rd();
    m=rd();
    r=rd();
    p=rd();
    for(int i=1;i<=n;i++) w[i]=rd();
    for(int i=1;i< n;i++){
        int x,y;
        x=rd();y=rd();
        add(x,y);
        add(y,x);
    }
    dfs1(r,0,0);
    dfs2(r,r);
    build(1,n,1);
//    for(int i=1;i<=n;i++) cout<<id[i]<<" ";
    for(int i=1;i<=m;i++){
        int q=rd();
        int x,y,z;
        switch(q){
            case 1:{
                x=rd();y=rd();z=rd();
                updata_link(x,y,z);
                break;
            }
            case 2:{
                x=rd();y=rd();
                cout<<query_link(x,y)%p<<endl;
                break;
            }
            case 3:{ 
                x=rd();y=rd();
                updata_son(x,y);
                break;
            }
            case 4:{
                x=rd();
                cout<<query_son(x)%p<<endl;
                break;
            }
        }
    }
    return 0;
}
;