Can anyone please give me some idea about this USACO problem? DELIVER — Delivery Route

Here is the editorial of the problem but I could not understand why 5N nodes are required.

Can someone please suggest some 20-30 1600-rated good DP problems? I was practising by filtering on problem sets, but most of them were based on the same repeated concepts. If you have any other resources please share.

I am getting TLE in this CSES problem.

Can anyone please tell me why it is showing TLE?

This problem came in today's Leetcode Weekly contest 296.

The solution to this problem is pretty straightforward.
But my question is:
how can I solve the problem if the condition: operations[i][1] does not exist in nums is not necessarily true.

As an example

Input: nums = [1,2,3,4], operations = [[2,3],[3,1],[1,4]]
Output: [4,4,4,4]

Can anyone please help me?

Question: You are given a set of points and you have to find out the maximum points which lie on the same line.

Now this question is available on both Uva and Leetcode. But the same test case gives different outputs in different OJs.

Testcase:

• Test Case in Leetcode input format
• Test Case in Uva input format

• According to the Leetcode: The answer is 5

• According to the test case on UDebug: The answer is 6

Can anyone please look into this matter? That would be a great help.