树状数组版，样例都过不了，求查错

#include <iostream>
#include <cstdio>
#include <algorithm>
using namespace std;
int n,a[100001],b[100001],c,d[1000001],ans;
int lowbit(int x)
{
    return x & -x;
}
void xg(int x,int y)
{
    for(int i=x;i<=n;i+=lowbit(i))
        d[i]=max(d[i],y);
}
int cx(int x)
{
    int ans=0;
    for(int i=x;i>0;i-=lowbit(i))
        ans=max(ans,d[i]);
    return ans;
}
int main()
{
	cin>>n;
	for(int i=1;i<=n;i++)
		cin>>a[i];
	for(int i=1;i<=n;i++)
		cin>>c,b[c]=i;
	for(int i=1;i<=n;i++)
	{
		d[i]=cx(b[a[i]])+1;
		xg(b[a[i]],d[i]);
		ans=max(ans,d[i]);
	}	
	cout<<ans;
	return 0;
}