```
class Solution {
public:
int lengthOfLIS(vector<int>& nums) {
int n = nums.size();
if (n == 0)
{
return 0;
}
vector<int> dp(n, 1);
int ret = 1;
for (int i = 1; i < n; i ++)
{
for (int j = 0; j < i; j ++)
{
if (nums[i] > nums[j] && dp[j] + 1 > dp[i])
{
dp[i] = dp[j] + 1;
ret = max(ret, dp[i]);
}
}
}
return ret;
}
};
```