**Time: 11:29pm IST**

- Solved A
- Solved B
- Solved C
- Couldn't think of D

**-- Up-solve :**

Solved A in 8 minutes. I think I could've solved it faster but my computer froze up. Nevertheless I should aim for sub 5 minute timings on A. I wonder do the people who solve it in 1-2 minutes even test their solutions? E.g. tourist who solved in 0:00 minutes. I used the coding format from 619's D problem and coded really nice solution. Happy to see up-solving paying off!

**O(n)**Really had fun time solving B. I imagined the circles intersecting as the rabbit's hops and felt pretty awesome after submitting the solution. I think elegant mathematics plus coding solutions is the best kind of computer science. Especially when you can visualize the concept in a 2D plane. I submitted a wrong answer which I knew in the back of my head was the case when he can hop in a single step to destination, guess I should think of all testcases before submitting answer.

**O(1)**First realize that solution will have either 1 letter hidden string or 2 letter. More than that isn't possible. Got this idea using some examples and mathematically too. I solved this then by storing results in 2D table. the table contained frequency of letters till that point. Then simple addition over this 26*n table for O(n) complexity gives answer. Really intuitive solution. See attached photo! photo

I had no idea how to work with D. I need to brush up on graph theory skills. Will watch William Fiset's Graph theory tutorials soon, then will try to solve as many questions as I can. Search for more resources.

**What I Learnt**

- Binary Search+ segment trees was a possible solution for D. How I don't know but the fact that they can be used is amazing.
- Calmly solving question with mathematical proof pays off.
- Up-solving previous contest was reason I could perform well this time. Need to keep this streak.

**--- New Things to learn:**

- I don't understand what is meant by Suffix Maximum array in D's editorial. Need to see some solutions.
- Using emplace_back() function
- Solving BFS questions to find shortest Distance from node to node.
- Djikstra's implementation I need to try out.

**---- Pending :**

- Read and try D

**----Song of the contest**

Thunderstruck by AC/DC :)