匪常简单

#include <bits/stdc++.h>
using namespace std;
const int N = 3005;
int n, a[N], b[N];
int f[N][N], ans;
int main(){
    cin >> n;
    for (int i=1; i<=n; i++)cin >> a[i];
    for (int i=1; i<=n; i++)cin >> b[i];
    for (int i=1; i <= n; i++){
        int maxn = 1;
        for (int j = 1; j <= n; j++){
            f[i][j] = f[i - 1][j];
            if (a[i] == b[j]) f[i][j] = max(f[i][j], maxn);
            if (b[j] < a[i]) maxn = max(maxn, f[i - 1][j] + 1);
        }
    }
    for (int i = 1; i <= n;i++) ans = max(ans, f[n][i]);
    cout << ans << endl;
    return 0;
}