Important Tricks and Pattern Recognition Techniques in DSA

Step 1 – Start with Constraints

🔹 Small Input Size (n ≤ 20)

PROBLEM EXAMPLES :

• Subsets (78) → Use recursion (take/not-take).

  • Trick: Think in terms of decision tree.

• Permutations (46) → Swap elements during recursion.

  • Trick: Fix one element at a time, recurse on the rest.

• Combination Sum (39) → DFS/backtracking.

  • Trick: Use “start index” to avoid duplicates.

• Word…