1.状态表示

2.集合：所有以i个数结尾的上升子序列

3.属性：Max

4.状态计算

 #include <iostream>

 using namespace std;

 const int N = 1010;

 int n;
 int f[N], a[N];

 int main()
 {
    cin >> n;
    for (int i = 1; i <= n; i ++) cin >> a[i];

    int res = 0;
    for (int i = 1; i <= n; i ++)
    {
        f[i] = 1; //只有一个元素
        for (int j = 1; j < i; j ++)
        {
            if (a[i] > a[j])
                f[i] = max(f[i], f[j] + 1);
        }
        res = max(res, f[i]);
    }  

    cout << res << endl;

    return 0;
 }