SDUT 1299 最长上升子序列

#include<iostream>
#include<cstring>

using namespace std;

int main()
{
int i, j, n, a[1002], len[1002], max;
cin >> n;
for (i=1; i<=n; i++)
{
cin >> a[i];
}
memset(len, 0, sizeof(len));
len[1]=1;
for (i=2; i<=n; i++)
{
max=0;
for (j=i-1; j>=1; j--)
{
if (max < len[j] && a[i] > a[j])
{
max=len[j];
}
}
len[i]=max+1;
}
max=0;
for (i=1; i<=n; i++)
{
if (max < len[i])
max=len[i];
}
cout << max << endl;
return 0;
}