洛谷 P3384 【模板】树链剖分

 

Code:

#include<cstdio>
#include<algorithm>
#include<iostream>
#include<cstring>
using namespace std;
typedef long long ll;
const int maxn=100000+2;
ll mod;int n;
int head[maxn],nex[maxn*2],to[maxn*2];
int p[maxn],dep[maxn],siz[maxn],son[maxn],top[maxn];int cnt,cnt2;     //树剖
ll sumv[maxn*4];
int lazy[maxn*4],A[maxn],st[maxn],ed[maxn],val[maxn];//线段树
void addedge(int u,int v){nex[++cnt]=head[u],head[u]=cnt,to[cnt]=v;}
void dfs1(int u,int fa,int cur){
	p[u]=fa,dep[u]=cur,siz[u]=1;
	for(int i=head[u];i;i=nex[i])
		if(to[i]!=fa)
	{
		dfs1(to[i],u,cur+1); 
		siz[u]+=siz[to[i]];
		if(son[u]==-1||siz[to[i]]>siz[son[u]])son[u]=to[i];
	}
}
void dfs2(int u,int tp){
   top[u]=tp,A[u]=++cnt2,st[u]=cnt2;
   if(son[u]!=-1)dfs2(son[u],tp);
   for(int i=head[u];i;i=nex[i])
   	    if(to[i]!=p[u]&&to[i]!=son[u])dfs2(to[i],to[i]);
   ed[u]=cnt2;
}
void down(int L,int R,int o){
	if(lazy[o]){
		int mid=(L+R)/2;
		lazy[o*2]+=lazy[o],lazy[o*2+1]+=lazy[o];
		sumv[o*2]+=(mid-L+1)*lazy[o],sumv[o*2+1]+=(R-mid)*lazy[o];
		lazy[o]=0;
		if(sumv[o*2]>=mod)sumv[o*2]%=mod;
		if(sumv[o*2+1]>=mod)sumv[o*2+1]%=mod;
		if(lazy[o*2]>=mod)lazy[o*2]%=mod;
		if(lazy[o*2+1]>=mod)lazy[o*2+1]%=mod;
	}
}
void build(int L,int R,int o,int arr[])
{
	if(L==R){sumv[o]=arr[L];if(sumv[o]>=mod)sumv[o]%=mod;return;}
	int mid=(L+R)/2;
	build(L,mid,o*2,arr);
	build(mid+1,R,o*2+1,arr);
	sumv[o]=sumv[o*2]+sumv[o*2+1];
	if(sumv[o]>=mod)sumv[o]%=mod;
}
void update(int l,int r,int k,int L,int R,int o){
   if(l<=L&&r>=R){
   	   lazy[o]+=k,sumv[o]+=(R-L+1)*k;
   	   if(lazy[o]>=mod)lazy[o]%=mod;
   	   if(sumv[o]>=mod)sumv[o]%=mod;
   	   return;
   }
   int mid=(L+R)/2;
   down(L,R,o);
   if(l<=mid)update(l,r,k,L,mid,o*2);
   if(r>mid)update(l,r,k,mid+1,R,o*2+1);
   sumv[o]=sumv[o*2]+sumv[o*2+1];
   if(sumv[o]>=mod)sumv[o]%=mod;
}
ll query(int l,int r,int L,int R,int o)
{
	if(l<=L&&r>=R)return sumv[o];
	int mid=(L+R)/2;
	down(L,R,o);
    ll ret=0;
    if(l<=mid)ret+=query(l,r,L,mid,o*2);
    if(r>mid)ret+=query(l,r,mid+1,R,o*2+1);
    sumv[o]=sumv[o*2]+sumv[o*2+1];
    if(sumv[o]>=mod)sumv[o]%=mod;
    if(ret>=mod)ret%=mod;
    return ret;
}
void up(int x,int y,int del){
	while(top[x]!=top[y]){
		if(dep[top[y]]<dep[top[x]]){update(A[top[x]],A[x],del,1,n,1);x=p[top[x]];}
		else {update(A[top[y]],A[y],del,1,n,1);y=p[top[y]];}
	}
	if(dep[x]<dep[y])update(A[x],A[y],del,1,n,1);
	else update(A[y],A[x],del,1,n,1);
}
ll look_up(int x,int y)
{
	ll _sum=0;
    while(top[x]!=top[y]){
		if(dep[top[y]]<dep[top[x]]){
			_sum+=query(A[top[x]],A[x],1,n,1);
			if(_sum>=mod)_sum%=mod;
			x=p[top[x]];
		}
		else {
			_sum+=query(A[top[y]],A[y],1,n,1);
			if(_sum>=mod)_sum%=mod;
			y=p[top[y]];
		}
	}
	if(dep[x]<dep[y])_sum+=query(A[x],A[y],1,n,1);
	else _sum+=query(A[y],A[x],1,n,1);
    if(_sum>=mod)_sum%=mod;
    return _sum;
}
int main()
{
   int m,r;
   scanf("%d%d%d",&n,&m,&r);scanf("%lld",&mod);
   for(int i=1;i<=n;++i)scanf("%d",&val[i]);
   for(int i=1;i<n;++i){int a,b;scanf("%d%d",&a,&b);addedge(a,b);addedge(b,a);}
   memset(son,-1,sizeof(son));

   dfs1(r,-1,1); 
   dfs2(r,r);
   for(int i=1;i<=n;++i)siz[A[i]]=val[i];
   build(1,n,1,siz);
   while(m--)
   {
   	int op;scanf("%d",&op);
   	if(op==1){
   		int x,y,z;scanf("%d%d%d",&x,&y,&z);up(x,y,z);
   	}
   	if(op==2){
        int x,y;scanf("%d%d",&x,&y);printf("%lld\n",look_up(x,y));
   	}
   	if(op==3){
   		int x,z;scanf("%d%d",&x,&z);
   		update(st[x],ed[x],z,1,n,1);
   	}
   	if(op==4){
   		int x;scanf("%d",&x);
   		printf("%lld\n",query(st[x],ed[x],1,n,1));
   	}
   }
   return 0;
}