Contest Experiences | Codeforce Round: #870 (Div. 2)

ABOUT THE CONTEST:

This contest was organized by Codeforces on May 5th, 2023. It consisted of 6 questions and the time given to solve them was 2 hours. Such contests Codeforces platform serve as a proving ground for algorithmic prowess and problem-solving skills.

Prizes/Offers:

While tangible prizes might be absent, the true reward lies in the intellectual satisfaction gained from solving intricate problems and the impact on one’s Codeforces rating—an ever-fluctuating badge of honor.

Link to the Contest: Codeforces Round 870 (Div. 2)

OVERVIEW OF THE QUESTIONS:

Round #870 (Div. 2) presented a diverse array of problems, ranging from classic algorithms to inventive data structures. The problem set aimed to challenge participants while ensuring a balance of difficulty levels.

MY EXPERIENCE:

Problem 1: Trust Nobody

Starting with the “Trust Nobody” challenge, it felt quite easy, the problem statement was straightforward and it took me around 6 minutes. Figuring out the honesty game was surprisingly straightforward. I went with a simple plan—counting the potential liars in the group. By sorting through everyone’s statements and checking for a consistent story, I nailed down a solution that didn’t overcomplicate things.

Problem 2: Lunatic Never Content

The second problem introduced is Lunatic Never Content—a quest involving arrays, remainders, and palindromes. The problem statement laid out the challenge clearly, and after around 15 minutes of contemplation, I had a solution ready to unfold. Navigating the landscape of remainders and palindromes, I approached the problem systematically. The task was to find the largest positive integer x, ensuring that the array generated by f(a, x) mirrored itself—a true palindrome. My solution gracefully achieved this goal, delivering a practical approach with an understanding of array mechanics.

Problem 3: Dreaming of Freedom

This was the first question in this question I stuck and lost around 25 minutes. I tried to solve it using graph theory and simulation approach but was still unable to crack it down.

Problem 4: Running Miles

The moment I read the question, joy washed over me because I have a strong hand on sorting and sliding window technique problems. I began by arranging the elements, setting up the sliding window, calculating the beauty score, and then systematically advancing through the sliding window to update the result. It took me around 15 minutes.

Problem 5: Walk the Runway

It was the most difficult question I was able to solve successfully in this contest. I solved this question using dynamic programming. I initialized a 2D array (dp), filled the DP table, found the maximum profit, and then backtracked for optimization. Finally, hurray! It compiled successfully. The entire process took me around 35 minutes to crack and compile successfully.

Problem 6: Fading into Fog

Even though I realized upon reading the last question that it might be beyond my current abilities, I didn’t lose hope. I attempted to solve it by applying pattern recognition and minimizing queries, but unfortunately, I struggled due to my limited proficiency in those areas.

CONCLUSION:

While I successfully tackled four out of six problems, those two unsolved questions made me realize the necessity of strengthening my understanding of the underlying concepts. It was more than a contest for me. It helped to let me know where I stand globally. The test took me around 1 hour and 40 minutes to solve.