树链剖分

复习一遍

#include<cstdio> 
#include<cstring> 
#include<iostream> 
#define N 150000 
#define For(i,x,y) for(int i=x;i<=y;++i) 
#define lson(x) (x<<1) 
#define rson(x) ((x<<1)+1) 
  
using namespace std; 
typedef long long LL; 
int n,m,r,M; 
struct SegTree{ 
    LL l[N*4],r[N*4],w[N*4],sum[N*4]; 
    void upd(int x){sum[x]=(sum[lson(x)]+sum[rson(x)]+w[x]*(r[x]-l[x]+1))%M;} 
    void build(int p,int L,int R){ 
        l[p]=L;r[p]=R;w[p]=0; 
        if(L==R)return; 
        int MID=(L+R)>>1; 
        build(lson(p),L,MID); 
        build(rson(p),MID+1,R); 
    } 
    void ins(int p,int x,int v){
        int L=l[p],R=r[p];int MID=(L+R)>>1; 
        if(L==R){ 
            w[p]+=v;w[p]%=M;upd(p);return; 
        } 
        if(x<=MID)ins(lson(p),x,v); 
        else      ins(rson(p),x,v); 
        upd(p); 
    } 
    void add(int x,int L,int R,int v){ 
        int mid=(l[x]+r[x])>>1; 
        if(l[x]==L&&r[x]==R){ 
            w[x]+=v;w[x]%=M;upd(x);return; 
        } 
        if(R<=mid)add(lson(x),L,R,v); 
        if(L>mid)add(rson(x),L,R,v); 
        if(R>mid&&L<=mid){ 
            add(lson(x),L,mid,v); 
            add(rson(x),mid+1,R,v); 
        } 
        upd(x); 
    } 
    int getsum(int x,int L,int R){ 
        int mid=(l[x]+r[x])>>1;int tans=w[x]*(R-L+1)%M; 
        if(l[x]==L&&r[x]==R) 
            return sum[x]; 
        if(R<=mid)return (getsum(lson(x),L,R)+tans)%M; 
        if(L>mid)return (getsum(rson(x),L,R)+tans)%M; 
        if(R>mid&&L<=mid)
            return (getsum(lson(x),L,mid)+getsum(rson(x),mid+1,R)+tans)%M; 
    } 
}T; 
  
struct Graph{ 
    struct E{ 
        int next,to; 
    }edge[N*2]; 
    int head[N];int cnt; 
    bool vis[N];LL v[N],size[N],son[N],top[N],id[N],deep[N],fa[N],xid[N]; 
    int sign; 
    void adde(int u,int v){ 
        edge[++cnt].to=v;edge[cnt].next=head[u];head[u]=cnt; 
        edge[++cnt].to=u;edge[cnt].next=head[v];head[v]=cnt; 
    } 
  
    void dfs1(int u){ 
        size[u]=1;int S=0; 
        for(int i=head[u];i;i=edge[i].next){ 
            int v=edge[i].to; 
            if(vis[v])continue;vis[v]=1; 
            deep[v]=deep[u]+1;fa[v]=u; 
            dfs1(v); 
            size[u]+=size[v]; 
            if(!S||size[v]>size[S])S=v; 
        } 
        son[u]=S; 
    } 
    void dfs2(int u,int tp){ 
        id[u]=++sign; 
        top[u]=tp; 
        if(!son[u]){xid[u]=sign;return;} 
        vis[son[u]]=1; 
        dfs2(son[u],tp); 
        for(int i=head[u];i;i=edge[i].next){ 
            int v=edge[i].to;if(vis[v])continue; 
            vis[v]=1;dfs2(v,v); 
        } 
        xid[u]=sign; 
    } 
    void prework(){ 
        cin>>n>>m>>r>>M; 
        For(i,1,n)scanf("%d",&v[i]); 
        For(i,1,n-1){ 
            int u,v;scanf("%d%d",&u,&v); 
            adde(u,v); 
        } 
        vis[r]=1; 
        dfs1(r); 
        memset(vis,0,sizeof(vis)); 
        vis[r]=1; 
        dfs2(r,r); 
        T.build(1,1,n); 
        For(i,1,n)T.ins(1,id[i],v[i]); 
    } 
    void add1(int u,int v,int w){ 
        if(deep[top[u]]<deep[top[v]])swap(u,v); 
        while(top[u]!=top[v]){ 
            T.add(1,id[top[u]],id[u],w); 
            u=fa[top[u]]; 
            if(deep[top[u]]<deep[top[v]])swap(u,v); 
        } 
        if(deep[u]<deep[v])swap(u,v); 
        T.add(1,id[v],id[u],w); 
    } 
    int get(int u,int v){ 
        int ans=0; 
        if(deep[top[u]]<deep[top[v]])swap(u,v); 
        while(top[u]!=top[v]){ 
            ans=(ans+T.getsum(1,id[top[u]],id[u]))%M; 
            u=fa[top[u]]; 
            if(deep[top[u]]<deep[top[v]])swap(u,v); 
        } 
        if(deep[u]<deep[v])swap(u,v); 
        ans=(ans+T.getsum(1,id[v],id[u]))%M; 
        return ans%M; 
    } 
    void add2(int u,int w){ 
        T.add(1,id[u],xid[u],w); 
    } 
    int get2(int u){ 
        return T.getsum(1,id[u],xid[u])%M; 
    } 
}G; 
  
int main(){ 
    G.prework(); 
    For(t,1,m){ 
        int opt; 
        scanf("%d",&opt); 
        int u,v,w; 
        if(opt==1){ 
            scanf("%d%d%d",&u,&v,&w); 
            G.add1(u,v,w); 
        } 
        if(opt==2){ 
            scanf("%d%d",&u,&v);printf("%d\n",G.get(u,v)); 
        } 
        if(opt==3){ 
            scanf("%d%d",&u,&w);G.add2(u,w); 
        } 
        if(opt==4){ 
            scanf("%d",&u);printf("%d\n",G.get2(u)); 
        } 
    } 
    return 0; 
}