BZOJ 4712: Flood digging to be completed

Code:

#include<bits/stdc++.h>
#define setIO(s) freopen(s".in","r",stdin) 
#define maxn 200001 
#define inf 1000000000 
#define lson (now<<1)
#define rson ((now<<1)|1)
using namespace std;
char ask[10]; 
int hd[maxn],to[maxn<<1],nex[maxn<<1],V[maxn],DP[maxn];  
int siz[maxn],hson[maxn],top[maxn],ln[maxn],dfn[maxn],fa[maxn],bot[maxn];  
int edges,n,Q,tim;  
void add(int u,int v)
{
	nex[++edges] = hd[u], hd[u] = edges,to[edges] = v; 
}
void dfs1(int u,int ff)
{
	siz[u]=1,fa[u]=ff;
	for(int i=hd[u];i;i=nex[i])
	{
	    int v=to[i]; 
	    if(v==ff) continue; 
	    dfs1(v,u); 
	    siz[u]+=siz[v]; 
	    if(siz[v]>siz[hson[u]]) hson[u]=v; 	
	}
}
void dfs2(int u,int tp)
{
	ln[++tim]=u,dfn[u]=tim,top[u]=tp; 
	if(hson[u]) 
		dfs2(hson[u],tp),bot[u]=bot[hson[u]]; 
	else 
		bot[u]=u; 
	for(int i=hd[u];i;i=nex[i])
	{
		int v=to[i]; 
		if(v==fa[u]||v==hson[u]) continue; 
		dfs2(v,v); 
	}
}
void dfs(int u)
{
	int sum=0; 
	for(int i=hd[u];i;i=nex[i])
	{
		int v=to[i];
		if(v==fa[u]||v==hson[u]) continue; 
		dfs(v); 
		sum+=DP[v]; 
	}
	DP[u]=min(V[u],sum); 
}

int sumv[maxn],lmin[maxn],val[maxn]; 
void pushup(int now)
{
	sumv[now]=sumv[lson]+sumv[rson]; 
	lmin[now]=min(lmin[lson],sumv[lson]+lmin0[rson]); 
} 
void build(int l,int r,int now)
{
	if(l>r) return; 
	if(l==r)
	{
		int u=ln[l],sum=0; 
		for(int i=hd[u];i;i=nex[i])
		{
			int v=to[i];
			if(v==fa[u]||v==hson[u]) continue; 
			sum+=DP[v];           
		}
		if(sum==0) 
			val[u]=V[u];
		else 
			val[u]=min(V[u],sum); 
		pushup(now); 
		return; 
	}
	int mid=(l+r)>>1; 
	build(l,mid,lson); 
	build(mid+1,r,rson); 
	pushup(now); 
}
int query(int l,int r,int now,int L,int R)
{
	if(l>=L&&r<=R) 
}

int main()
{
	setIO("input"); 
	scanf("%d",&n); 
	for(int i=1;i<=n;++i) scanf("%d",&V[i]); 
	for(int i=1,u,v;i<n;++i)
	{
		scanf("%d%d",&u,&v),add(u,v),add(v,u); 
	}

	dfs1(1,0),dfs2(1,1),dfs(1),DP[0]=inf, build(1,n,1);  

	scanf("%d",&Q);
	while(Q--)
	{
		scanf("%s",ask);
		if(ask[0]=='C') 
		{

		}
		if(ask[0]=='Q')
		{

		}
	}
	return 0; 
}