Clear all DSA rounds, create sub issues for each pattern having sub-sub-issues of problems.

[Veercodeprog]

By mastering these 20 DSA patterns

1. Fast and Slow Pointer

• Cycle detection method
• O(1) space efficiency
• Linked list problems

2. Merge Intervals

• Sort and merge
• O(n log n) complexity
• Overlapping interval handling

3. Sliding Window

• Fixed/variable window
• O(n) time optimization
• Subarray/substring problems

4. Islands (Matrix Traversal)

• DFS/BFS traversal
• Connected component detection
• 2D grid problems

5. Two Pointers

• Dual pointer strategy
• Linear time complexity
• Array/list problems

6. Cyclic Sort

• Sorting in cycles
• O(n) time complexity
• Constant space usage

7. In-place Reversal of Linked List

• Reverse without extra space
• O(n) time efficiency
• Pointer manipulation technique

8. Breadth First Search

• Level-by-level traversal
• Uses queue structure
• Shortest path problems

9. Depth First Search

• Recursive/backtracking approach
• Uses stack (or recursion)
• Tree/graph traversal

10. Two Heaps

• Max and min heaps
• Median tracking efficiently
• O(log n) insertions

11. Subsets

• Generate all subsets
• Recursive or iterative
• Backtracking or bitmasking

12. Modified Binary Search

• Search in variations
• O(log n) time
• Rotated/specialized arrays

13. Bitwise XOR

• Toggle bits operation
• O(1) space complexity
• Efficient for pairing

14. Top 'K' elements

• Use heap/quickselect
• O(n log k) time
• Efficient selection problem

15. K-way Merge

• Merge sorted lists
• Min-heap based approach
• O(n log k) complexity

16. 0/1 Knapsack (Dynamic Programming)

• Choose or skip items
• O(n * W) complexity
• Maximize value selection

17. Unbounded Knapsack (Dynamic Programming)

• Unlimited item choices
• O(n * W) complexity
• Multiple item selection

18. Topological Sort (Graphs)

• Directed acyclic graph
• Order dependency resolution
• Uses DFS or BFS

19. Monotonic Stack

• Maintain increasing/decreasing stack
• Optimized for range queries
• O(n) time complexity

20. Backtracking

• Recursive decision-making
• Explore all possibilities
• Pruning with constraints