TJOI2015 旅游

Description

 

Input

Output

 

Sample Input

输入：
3
1 2 3
1 2
2 3
2
1 2 100
1 3 100

Sample Output

输出：
1
1

 

Data Constraint

 

 

解法：显然的链剖。维护区间max,min，前面减后面的max,后面减前面的max即可

#include<cstdio>
#include<cstdlib>
#include<algorithm>
#include<cmath>
#include<cstring>

using namespace std;

struct Tree{
    int lr,rl,mx,mn,bz;
}tr[400011];

Tree Tm[111];
int g[50011],next[100011],y[100011],num[50011],dep[50011],fa[50011],top[50011];
int id[50011],son[50011],size[50011],pm[111],sm[111],val[50011];
int tot,tt,n,i,x,z,q,ans,m;

struct AA{
    int l,r,k,sh;
}que[111];

void star(int i,int j)
{
    tt++;
    next[tt]=g[i];
    g[i]=tt;
    y[tt]=j;
}

void build_chain(int root)
{
    int x;
    x=root;
    while(x){
        tot++;
        id[tot]=x;
        num[x]=tot;
        top[x]=root;
        x=son[x];
    }
}

void dfs(int x)
{
    int j,k;
    size[x]=1;
    j=g[x];
    while(j!=0){
        k=y[j];
        if(k!=fa[x]){
            fa[k]=x;
            dep[k]=dep[x]+1;
            dfs(k);
            size[x]+=size[k];
            if(size[k]>size[son[x]]){
                if(son[x])build_chain(son[x]);
                son[x]=k;
            }
            else build_chain(k);
        }
        j=next[j];
    }
    
}

Tree Merge(Tree a,Tree b)
{
    Tree c;
    c.mx=max(a.mx,b.mx);
    c.mn=min(a.mn,b.mn);
    c.rl=max(a.rl,b.rl);
    c.rl=max(c.rl,b.mx-a.mn);
    c.lr=max(a.lr,b.lr);
    c.lr=max(c.lr,a.mx-b.mn);
    return c;
}

void up(int t)
{
    Tree a,b;
    Tree &c=tr[t];
    a=tr[t+t];b=tr[t+t+1];
    c.mx=max(a.mx,b.mx);
    c.mn=min(a.mn,b.mn);
    c.rl=max(a.rl,b.rl);
    c.rl=max(c.rl,b.mx-a.mn);
    c.lr=max(a.lr,b.lr);
    c.lr=max(c.lr,a.mx-b.mn);

}

void build(int l,int r,int t)
{
    if(l==r){
        tr[t].mx=tr[t].mn=val[id[l]];
        tr[t].lr=tr[t].rl=0;
        tr[t].bz=0;
        return;
    }
    int mid;
    mid=(l+r)/2;
    build(l,mid,t+t);
    build(mid+1,r,t+t+1);
    tr[t].bz=0;
    up(t);
}

void change(int t,int x)
{
    tr[t].bz+=x;
    tr[t].mx+=x;
    tr[t].mn+=x;
}

void down(int t,int l,int r)
{
    if(l==r)return;
    if(tr[t].bz){
        change(t+t,tr[t].bz);
        change(t+t+1,tr[t].bz);
        tr[t].bz=0;
    }
}

void insert(int t,int l,int r,int x,int y,int z)
{
    down(t,l,r);
    if(l==x&&r==y){
        change(t,z);
        return;
    }
    int mid;
    mid=(l+r)/2;
    if(y<=mid)insert(t+t,l,mid,x,y,z);
    if(x>mid)insert(t+t+1,mid+1,r,x,y,z);
    if(x<=mid&&y>mid){
        insert(t+t,l,mid,x,mid,z);
        insert(t+t+1,mid+1,r,mid+1,y,z);
    }
    up(t);
}

Tree ask(int t,int l,int r,int x,int y)
{
    down(t,l,r);
    if(l==x&&r==y)return tr[t];
    Tree re;
    int mid;
    mid=(l+r)/2;
    if(y<=mid)re=ask(t+t,l,mid,x,y);
    if(x>mid)re=ask(t+t+1,mid+1,r,x,y);
    if(x<=mid&&y>mid)re=Merge(ask(t+t,l,mid,x,mid),ask(t+t+1,mid+1,r,mid+1,y));
    up(t);
    return re;
}

bool cmp(AA a,AA b)
{
    if(a.k==b.k){
        if(a.k==1)return a.sh<b.sh;
        else return a.sh>b.sh;
    }
    else return a.k<b.k;
}

void Work(int st,int ed,int ad)
{
    int bs,be,mn[3],i,ts(0);
    bs=1;be=2;
    mn[1]=mn[2]=0;
    while(true){
        if(top[st]==top[ed]){
            if(dep[st]<dep[ed])swap(st,ed),swap(bs,be);
            ts++;
            que[ts].l=num[ed];
            que[ts].r=num[st];
            que[ts].k=bs;
            que[ts].sh=++mn[bs];
            break;
        }
        else{
            if(dep[top[st]]<dep[top[ed]])swap(st,ed),swap(bs,be);
            ts++;
            que[ts].l=num[top[st]];
            que[ts].r=num[st];
            que[ts].k=bs;
            que[ts].sh=++mn[bs];
            st=fa[top[st]];
        }
    }
    sort(que+1,que+1+ts,cmp);
    for(i=1;i<=ts;i++)insert(1,1,n,que[i].l,que[i].r,ad);
    pm[0]=214748364;
    sm[ts+1]=-214748364;
    for(i=1;i<=ts;i++)Tm[i]=ask(1,1,n,que[i].l,que[i].r);
    for(i=1;i<=ts;i++)pm[i]=min(pm[i-1],Tm[i].mn);
    for(i=ts;i>=1;i--)sm[i]=max(sm[i+1],Tm[i].mx);
    ans=-214748364;
    for(i=1;i<=ts;i++){
        if(que[i].k==2)ans=max(ans,Tm[i].rl);
        else ans=max(ans,Tm[i].lr);
        ans=max(ans,sm[i+1]-pm[i]);
    }
}

int main()
{
    scanf("%d",&n);
    for(i=1;i<=n;i++)scanf("%d",&val[i]);
    for(i=1;i<n;i++){
        scanf("%d%d",&x,&z);
        star(x,z);
        star(z,x);
    }
    scanf("%d",&m);
    dfs(1);
    build_chain(1);
    build(1,n,1);
    for(i=1;i<=m;i++){
        scanf("%d%d%d",&x,&z,&q);
        Work(x,z,q);
        printf("%d
",ans);
    }
}