树上倍增求链上最大值或最小值

倍增求链上点最大值

inline int LCA(int x,int y)
{
	int maxn=max(w[x],w[y]);
	if (deep[x]>deep[y]) swap(x,y);
	int k=log2(deep[y]);
	for (int i=k;i>=0;i--)
	if (deep[f[i][y]]>=deep[x])
	{
		maxn=max(maxn,maxx[i][y]);
		y=f[i][y];
	}
	if (x==y) return max(maxn,w[x]);
	for (int i=k;i>=0;i--)
	if (f[i][y]!=f[i][x])
	{
		maxn=max(maxn,maxx[i][x]);
		maxn=max(maxn,maxx[i][y]);
		y=f[i][y];
		x=f[i][x];
	}
	return max(maxn,maxx[0][x]);
}
inline void dfs(int x,int fa)
{
	deep[x]=deep[fa]+1;
	f[0][x]=fa;
	maxx[0][x]=w[fa];
	for (int i=1;(1<<i)<=deep[x];i++)
	{
		f[i][x]=f[i-1][f[i-1][x]];
		maxx[i][x]=max(maxx[i-1][x],maxx[i-1][f[i-1][x]]);
	}
	for (int i=head[x];i;i=ed[i].next)
	if (ed[i].e!=fa) dfs(ed[i].e,x);
	return ;
}

倍增求链上边最大值

inline int LCA(int x,int y)
{
	int maxx=0;
	if (deep[x]>deep[y]) swap(x,y);
	int k=log2(deep[y]);
	for (int i=k;i>=0;i--)
	if (deep[f[i][y]]>=deep[x])
	{
		maxx=max(maxv[i][y],maxx);
		y=f[i][y];
	}
	if (x==y) return maxx;
	for (int i=k;i>=0;i--)
	if (f[i][y]!=f[i][x])
	{
		maxx=max(maxv[i][y],maxx);
		maxx=max(maxv[i][x],maxx);
		y=f[i][y];
		x=f[i][x];
	}
	return max(maxx,max(maxv[0][x],maxv[0][y]));
}
inline void dfs2(int x,int fa)
{
	f[0][x]=fa;
	for (int i=1;(1<<i)<=deep[x];i++)
	{
		f[i][x]=f[i-1][f[i-1][x]];
		maxv[i][x]=max(maxv[i-1][x],maxv[i-1][f[i-1][x]]);
	}
	for (int i=head[x];i;i=ed[i].net)
	if (ed[i].e!=fa) dfs2(ed[i].e,x);
	return ;
}
inline void dfs1(int x,int fa)
{
	deep[x]=deep[fa]+1;
	for (int i=head[x];i;i=ed[i].net)
	if (ed[i].e!=fa) dfs1(ed[i].e,x);
	else maxv[0][x]=ed[i].v;
	return ;
}