DAY 16 Strengthening Array Problem-Solving Skills

Hello Everyone!

I am Somuya Khandelwal, and I’m thrilled to share my progress from Day 1 of Week 4 in my competitive programming journey. Today’s focus was on Array-based problems, a versatile category that requires a mix of logical thinking, efficient implementation, and creativity. The problems tackled today were engaging and helped reinforce fundamental concepts.

What I Worked On Today

1. Insert Delete Get Random O(1) (Medium Difficulty)

   • Implement a data structure that supports insert, delete, and getRandom operations in constant time.
   • Approach:
     • Used a combination of a hashmap for O(1) lookups and an array for O(1) random access.
     • Maintained the mapping between elements and their indices for efficient deletion.
   • What I Learned:
     • Combining multiple data structures (hashmap and array) is often the key to solving complex problems efficiently.
     • Ensuring constant-time operations requires careful management of indices during insertions and deletions.

2. Integer to Roman (Medium Difficulty)

   • Convert an integer to its Roman numeral representation.
   • Approach:
     • Used a greedy algorithm to match the largest Roman numeral symbols repeatedly, subtracting their values until the integer was reduced to zero.
     • Iterated over a predefined list of numeral-value pairs.
   • What I Learned:
     • Greedy approaches are effective for problems involving fixed mappings or patterns.
     • Iterating over sorted numeral-value pairs simplifies logic and ensures correctness.

3. Zig Zag Conversion (Medium Difficulty)

   • Convert a string into a zig-zag pattern with a given number of rows, then read row by row.
   • Approach:
     • Simulated the zig-zag traversal by maintaining a list of rows and a variable to track the current direction.
     • Appended characters to rows while traversing in a "down-up" pattern.
   • What I Learned:
     • Simulating patterns using auxiliary data structures (like row lists) is often the easiest way to solve such problems.
     • Carefully managing state variables (e.g., direction changes) is critical in pattern-based problems.

What I Learned Today

1. Combining Data Structures for Efficiency:

   • Problems like Insert Delete Get Random O(1) highlight the power of combining multiple data structures to achieve optimal performance.

2. Greedy Algorithms:

   • Problems involving fixed mappings or repetitive patterns, like Integer to Roman, often benefit from greedy solutions.

3. Simulating Patterns with Arrays:

   • Simulating processes like zig-zag traversal is easier when auxiliary data structures are used to track intermediate states.

4. Edge Case Handling:

   • Each problem required careful handling of edge cases, such as an empty input string in Zig Zag Conversion or large numbers in Integer to Roman.

Reflections and Challenges

The Insert Delete Get Random O(1) problem was particularly challenging due to the need to balance hashmap and array operations while maintaining constant time complexity. Debugging the index management during deletions took some effort but was incredibly rewarding once resolved. The Zig Zag Conversion problem was fun to implement, especially with its visually intuitive pattern.

Looking Ahead

Tomorrow, I’ll shift focus to Math-based problems, including Palindrome Number, Plus One, and Factorial Trailing Zeros. These tasks will test my ability to combine mathematical reasoning with efficient coding techniques.

Thank you for following along on my journey! Stay tuned for more updates and learnings as I continue to grow in competitive programming.