LeetCode 300. Longest Increasing Subsequence (DP)

class Solution {
public:
    int dp[5005];
    int lengthOfLIS(vector<int>& nums) {
        
        int ans=0;
        for(int i=0;i<nums.size();i++)
        {
            dp[i]=1;
            for(int j=i-1;j>=0;j--)
            {
                if(nums[i]>nums[j])
                    dp[i]=max(dp[i],dp[j]+1);
            }
            ans=max(ans,dp[i]);
        }
        
        return ans;
        
        
    }
};

class Solution {
public:
    int dp[5005];
    int len;
    int lengthOfLIS(vector<int>& nums) {
        
        len=0;
        for(int i=0;i<nums.size();i++)
        {
            if(len==0||nums[i]>dp[len-1])
                dp[len++]=nums[i];
            else
            {
                int index = find(nums[i]);
                dp[index]=nums[i];
            }
        }
       
        return len;
        
    }
    
    int find(int x)
    {
        int l = 0;
        int r = len-1;
        while(l<=r)
        {
            int mid = (l+r)/2;
            if(dp[mid]<x)
            {
                l = mid+1;
            }
            else if(dp[mid]>x)
            {
                r = mid-1;
            }
            else
                return mid;
        }
        
        return l;
    }
};