Poj 2533 Longest Ordered Subsequence

#include<iostream>
#include<stdio.h>
using namespace std;
const int maxn = 1001;
int a[maxn],dp[maxn];
int main(){
    int n;
    cin>>n;
    for(int i=1;i<=n;i++){
        scanf("%d",&a[i]);
        dp[i] =1;
    }    
    int ans = 0;
    for(int i=1;i<=n;i++){
        for(int j=i+1;j<=n;j++){
            if(a[j]>a[i]){
                dp[j] = max(dp[j],dp[i]+1);
            }
        }
    }
    for(int i=1;i<=n;i++)
        ans = max(ans,dp[i]); 
    cout<<ans<<endl; 
    return 0;
}