most-asked-techniques.md

Most Commonly Asked LeetCode Techniques

1️⃣ Sliding Window

• Use case: Problems involving contiguous subarrays or substrings.
• Common problems:
  • Longest Substring Without Repeating Characters
  • Minimum Size Subarray Sum
  • Find All Anagrams in a String

---

2️⃣ Two Pointers

• Use case: Searching, sorting, or working with sorted arrays.
• Common problems:
  • Two Sum II - Input Array Is Sorted
  • 3Sum
  • Container With Most Water

---

3️⃣ Hashing (HashMap / HashSet)

• Use case: Problems requiring quick lookups, frequency counts, or duplicate detection.
• Common problems:
  • Two Sum
  • Valid Anagram
  • Longest Consecutive Sequence

---

4️⃣ Prefix Sum

• Use case: Subarray sum-related problems.
• Common problems:
  • Subarray Sum Equals K
  • Find Pivot Index
  • Product of Array Except Self

---

5️⃣ Binary Search

• Use case: Searching in sorted arrays or search-space optimization.
• Common problems:
  • Binary Search
  • Search in Rotated Sorted Array
  • Find Minimum in Rotated Sorted Array

---

6️⃣ Dynamic Programming (DP)

• Use case: Problems with overlapping subproblems and optimal substructure.
• Common problems:
  • Climbing Stairs
  • Longest Palindromic Substring
  • House Robber

---

7️⃣ Backtracking

• Use case: Generating all possible combinations or permutations.
• Common problems:
  • Letter Combinations of a Phone Number
  • Combination Sum
  • Sudoku Solver

---

8️⃣ Bit Manipulation

• Use case: Finding unique elements or performing bitwise operations.
• Common problems:
  • Single Number
  • Power of Two
  • Sum of Two Integers

---

9️⃣ Stack & Monotonic Stack

• Use case: Problems related to parentheses, stock spans, and histogram bars.
• Common problems:
  • Valid Parentheses
  • Daily Temperatures
  • Largest Rectangle in Histogram

---

🔟 Graphs & BFS/DFS

• Use case: Traversing connected components, shortest paths, or cycle detection.
• Common problems:
  • Number of Islands
  • Word Ladder
  • Course Schedule

---

1️⃣1️⃣ Heap / Priority Queue

• Use case: Problems that require frequent min/max element retrieval.
• Common problems:
  • Kth Largest Element in an Array
  • Top K Frequent Elements
  • Merge K Sorted Lists

---

Want a list of problems for a specific topic? 🚀