洛谷P1439

最长公共子序列考虑到元素各异，变成最上不降子序列

#include <bits/stdc++.h>
/*
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/hash_policy.hpp>
*/
using namespace std;

const double eps = 1e-10;
const double pi = 3.1415926535897932384626433832795;
const double eln = 2.718281828459045235360287471352;

#define f(i, a, b) for (int i = a; i <= b; i++)
#define scan(x) scanf("%d", &x)
#define mp make_pair
#define pb push_back
#define lowbit(x) (x&(-x))

#define fi first
#define se second
#define SZ(x) int((x).size())
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define summ(a) (accumulate(all(a), 0ll))

typedef unsigned long long ull;
typedef pair<int,int> pii;
typedef vector<int> vi;

using ll=long long;

ll n,a[(int)1e5+9],b[(int)1e5+9];
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    cin>>n;
    for(int i=1,x;i<=n;++i)cin>>x,a[x]=i;
    for(int i=1,x;i<=n;++i)cin>>x,b[i]=a[x];
    vi v(1,-1);
    for(int i=1;i<=n;++i){
        if(b[i]>v.back())v.push_back(b[i]);
        else *upper_bound(all(v),b[i])=b[i];
    }
    cout<<v.size()-1;
    return 0;
}