dfs部分检查过应该没有问题

树状数组区间改区间查，树剖都是第一次写

问题应该出在这两部分

谢谢大佬

#include <iostream>
#include <cstdio>

using namespace std;

const int N=3000000;
int n,m,r,p;
int w[N];
struct edge
{
    int to,next;
}e[N];
int cnt,head[N];
void add(int x,int y)
{
    cnt++;
    e[cnt].to=y;
    e[cnt].next=head[x];
    head[x]=cnt;
}
///树状数组部分
int c1[N],c2[N];
int updata(int x,int k)
{
    int xx=x;
    while(x<=n)
    {
        c1[x]+=k;
        c2[x]+=k*(xx-1);
        x+=x&(-x);
    }
}
int getsum(int x)
{
    int ans=0,xx=x;
    while(x)
    {
        ans+=xx*c1[x]-c2[x];
        x-=x&(-x);
    }
    return ans;
}
int up(int x,int y,int k)
{
    if(x>y)swap(x,y);
    updata(x,k);
    updata(y+1,-k);
}
int get(int x,int y)
{
    if(x>y)swap(x,y);
    return getsum(y) - getsum(x-1);
}
///DFS部分
int son[N],siz[N],top[N],dep[N],fa[N],dfn[N];
int dfss=0;
void dfs1(int u,int f,int de)
{
    dep[u]=de;
    fa[u]=f;
    siz[u]=1;
    int pigson=-1;
    for(int i=head[u];i;i=e[i].next)
    {
        int v=e[i].to;
        if(v==f)continue;
        dfs1(v,u,de+1);
        siz[u]+=siz[v];
        if(siz[v]>pigson)
        {
            son[u]=v;
            pigson=siz[v];
        }
    }
}
void dfs2(int u,int tf)
{
    dfn[u]=++dfss;
    c1[dfss]=w[u];
    top[u]=tf;
    if(son[u]==0)return ;
    dfs2(son[u],tf);
    for(int i=head[u];i;i=e[i].next)
    {
        int v=e[i].to;
        if(dfn[v]==0)
        {
            dfs2(v,v);
        }
    }
}

///树剖部分
int line_add(int u,int v,int k)
{
    k%=p;
    while(top[u]!=top[v])
    {
        if(dep[top[u]]<dep[top[v]])
        {
            swap(u,v);
        }
        up(dfn[top[u]],dfn[u],k);
        u=fa[top[u]];
    }
    if(dep[u]>dep[v])
    {
        swap(u,v);
    }
    up(dfn[u],dfn[v],k);
}
int line_find(int u,int v)
{
    int ans=0;
    while(top[u]!=top[v])
    {
        if(dep[top[u]]<dep[top[v]])
        {
            swap(u,v);
        }
        ans=(ans+get(dfn[top[u]],dfn[u]))%p;
        u=fa[top[u]];
    }
    if(dep[u]>dep[v])
    {
        swap(u,v);
    }
    ans=(ans+get(dfn[u],dfn[v]))%p;
    return ans;
}
int tree_find(int u)
{
    return get(dfn[u],dfn[u]+siz[u]-1);
}

void tree_add(int u,int k)
{
    k%=p;
    up(dfn[u],dfn[u]+siz[u]-1,k);
}
///main部分
int main()
{
    int i,j,k;
    cin>>n>>m>>r>>p;
    for(i=1;i<=n;i++)
    {
        cin>>w[i];
    }
    for(i=1;i<n;i++)
    {
        int x,y;
        cin>>x>>y;
        add(x,y);
        add(y,x);
    }
    dfs1(r,0,1);
    /*
    for(i=1;i<=n;i++)
    {
        printf("siz%d son%d fa%d dep%d\n",siz[i],son[i],fa[i],dep[i]);
    }
    */
    dfs2(r,r);
    /*
    for(i=1;i<=n;i++)
    {
        printf("top%d dfn%d\n",top[i],dfn[i]);
    }
    */
    for(i=1;i<=m;i++)
    {
        int b;
        cin>>b;
        if(b==1)
        {
            int x,y,z;
            cin>>x>>y>>z;
            line_add(x,y,z);
        }
        if(b==2)
        {
            int x,y;
            cin>>x>>y;
            cout<<line_find(x,y)<<endl;
        }
        if(b==3)
        {
            int x,y;
            cin>>x>>y;
            tree_add(x,y);
        }
        if(b==4)
        {
            int x;
            cin>>x;
            cout<<tree_find(x)<<endl;
        }
    }
    return 0;
}