【ZJOI2008】树的统计（树链剖分）-优快云博客

Solution:
就是树链剖分入门题啦~
// luogu-judger-enable-o2
#include<bits/stdc++.h>
#define N 30005
#define M 200005
#define lson now<<1
#define rson now<<1|1
#define INF 0x7fffffff
using namespace std;
int n,tot,first[N],val[N];
int father[N],size[N],maxson[N],depth[N],top[N],id[N],sign,wnew[N];
int ans=0;
struct Edge
{
    int to,next;
}edge[2*N];
inline void addedge(int x,int y)
{
    tot++;
    edge[tot].to=y;
    edge[tot].next=first[x];
    first[x]=tot;
}
struct node
{
    int l,r,sum,maxv;
}tree[4*N];
inline void build(int l,int r,int now)
{
    tree[now].l=l,tree[now].r=r,tree[now].sum=0,tree[now].maxv=0;
    if(l==r)
    {
        tree[now].sum=wnew[l];
        tree[now].maxv=wnew[l];
        return;
    }
    int m=(l+r)>>1;
    build(l,m,lson);
    build(m+1,r,rson);
    
    tree[now].sum=tree[lson].sum+tree[rson].sum;
    tree[now].maxv=max(tree[lson].maxv,tree[rson].maxv);
}
inline void update(int now,int x,int k)
{
    if(tree[now].l==x&&tree[now].r==x)
    {
        tree[now].sum=k;
        tree[now].maxv=k;
        return;
    }
    int m=(tree[now].l+tree[now].r)>>1;
    if(x<=m) update(lson,x,k);
    else update(rson,x,k);
    
    tree[now].sum=tree[lson].sum+tree[rson].sum;
    tree[now].maxv=max(tree[lson].maxv,tree[rson].maxv);
}
inline void query_sum(int l,int r,int now)
{
    if(l<=tree[now].l&&tree[now].r<=r) 
    {
        ans+=tree[now].sum;
        return;
    }
    int m=(tree[now].l+tree[now].r)>>1;
    if(l<=m)    query_sum(l,r,lson);
    if(r>m) query_sum(l,r,rson);
}
inline void query_max(int l,int r,int now)
{
    if(l<=tree[now].l&&tree[now].r<=r) 
    {
        ans=max(ans,tree[now].maxv);
        return;
    }
    int m=(tree[now].l+tree[now].r)>>1;
    if(l<=m)    query_max(l,r,lson);
    if(r>m) query_max(l,r,rson);
}
inline void dfs1(int now,int fa)
{
    father[now]=fa;
    size[now]=1;
    depth[now]=depth[fa]+1;
    for(int u=first[now];u;u=edge[u].next)
    {
        int vis=edge[u].to;
        if(vis==fa) continue;
        dfs1(vis,now);
        size[now]+=size[vis];
        if(size[vis]>size[maxson[now]]) maxson[now]=vis;
    }
}
inline void dfs2(int now,int topf)
{
    id[now]=++sign;
    top[now]=topf;
    wnew[sign]=val[now];
    if(maxson[now]) dfs2(maxson[now],topf);
    for(int u=first[now];u;u=edge[u].next)
    {
        int vis=edge[u].to;
        if(vis==father[now]||vis==maxson[now])  continue;
        dfs2(vis,vis);
    }
}
inline int qmax(int x,int y)
{
    int ret=-INF;
    while(top[x]!=top[y])
    {
        if(depth[top[x]]<depth[top[y]]) swap(x,y);//默认x比y深 
    
        ans=-INF;
        query_max(id[top[x]],id[x],1);
        ret=max(ret,ans);
    
        x=father[top[x]];
    }
    if(depth[x]<depth[y]) swap(x,y);
    
    ans=-INF;
    query_max(id[y],id[x],1);
    return max(ret,ans);
}
inline int qsum(int x,int y)
{
    int ret=0;
    while(top[x]!=top[y])
    {
        if(depth[top[x]]<depth[top[y]]) swap(x,y);//默认x比y浅
    
        ans=0;
        query_sum(id[top[x]],id[x],1);
        ret+=ans;
    
        x=father[top[x]];
    }
    if(depth[x]<depth[y]) swap(x,y);
    
    ans=0;
    query_sum(id[y],id[x],1);
    ret+=ans;
    
    return ret;
}
int main()
{
    cin>>n;
    for(int i=1;i<=n-1;i++)
    {
        int x,y;
        cin>>x>>y;
        addedge(x,y);
        addedge(y,x);
    }
    for(int i=1;i<=n;i++)   cin>>val[i];
    dfs1(1,0);
    dfs2(1,1);
    build(1,n,1);
    int Q;
    cin>>Q;
    while(Q--)
    {
        string s;
        int x,y;
        cin>>s>>x>>y;
        if(s=="CHANGE") update(1,id[x],y);
        if(s=="QMAX") cout<<qmax(x,y)<<'\n';
        if(s=="QSUM") cout<<qsum(x,y)<<'\n';
    }
    return  0;
}
转载于:https://www.cnblogs.com/Patrickpwq/articles/9467483.html