LeetCode

The holy grail of programming interviews. Plus I think it’s actually pretty fun → focusing more on Competitive Programming because it’s harder

I actually suck at LeetCode for some reason (started summer 2022)

• 2022-12-22: Actually getting better, I can do hards

You can use Binarysearch to practice by company (NOPE, site is down)

Unsolved problems:

• https://leetcode.com/problems/minimize-maximum-value-in-a-grid/?envType=weekly-question&envId=2024-11-22 - This is just long and tedious, I think I can do it

Weaknesses:

• Knapsack DP
• Implement the Sorting Algorithms
• Quickselect to select the k-th smallest element in $O(n)$ time
• Be faster at tree algorithms

However, I think the Codeforces problems are a lot more rewarding to solve, I guess just because they are harder.

Okay, i lost to ryan today for this problem 2024-11-26

• https://leetcode.com/problems/previous-permutation-with-one-swap/
  • I was not familiar with the idea and could not handle the pressure of visualizing the largest number smaller than that
  • For bits, it’s simply -1
  • But like for a swap, how does that work??
• Also this daily problem https://leetcode.com/problems/shortest-distance-after-road-addition-queries-i/?envType=daily-question&envId=2024-11-27

Main Topics

1. Sliding Window
2. Two Pointers
3. Merge Intervals
4. Cyclic Sort
5. Binary Search
6. Shuffling an array

• Permutations
• Sliding Window
• Cycle Detection
• BFS
• DFS
• Topological Sort
• Backtracking

https://hackernoon.com/14-patterns-to-ace-any-coding-interview-question-c5bb3357f6ed

Other CP Topics

• NP-Complete
• Game Theory
• Probability
• Convex Hull
• Hamming Distance
• Manhattan Distance
• Euclidean Distance

Algorithms

• Selection Algorithm

Problems

• Maximum Subarray
• Subsets
• Permutations
• Travelling Salesman Problem
• Pigeonhole Principle

Strategy

1. Attempt the problem (obviously)
2. If too hard, see if you have solved similar problems in the past
3. Read the discussion forum, but just look at the titles for inspiration
4. If it still doesn’t work, check the answer, but do not just copy paste. Try to understand and put your own implementation of it without looking at the original solutions

Leetcode Tip (NEVER DO THE SAME PROBLEMS)

Do not repeat trying the same problems, because you are actually trying to get better at pattern recognition.

If the interviewer gives you a variation of the problem you solved, then you don’t know how to exactly tackle it, so there is no point.

Related

• Competitive Programming