Backtracking Study Guide

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Combination Problems

Combination problems involve selecting a subset of elements from a given set, where the order doesn't matter.

• 🟨 17. Letter Combinations of a Phone Number
• 🟨 39. Combination Sum [Solution]
• 🟨 40. Combination Sum II [Solution]
• 🟨 77. Combinations [Solution]
• 🟨 22. Generate Parentheses

Permutation Problems

Permutation problems involve arranging all the elements of a set into different sequences.

• 🟨 46. Permutations [Solution]
• 🟨 47. Permutations II

Subset Problems

Subset problems involve finding all possible subsets of a given set.

• 🟨 78. Subsets
• 🟨 90. Subsets II

Graph and Matrix Search Problems

These problems involve searching through graphs or matrices using backtracking.

• 🟥 37. Sudoku Solver
• 🟨 79. Word Search [Solution]
• 🟥 212. Word Search II [Solution]

Chessboard Problems

Chessboard problems often involve placing pieces on a board while satisfying certain constraints.

• 🟥 51. N-Queens
• 🟥 52. N-Queens II

Problem Difficulty Legend

• 🟩 Easy
• 🟨 Medium
• 🟧 Medium-Hard
• 🟥 Hard
• ⬛ Very Hard

Additional Resources

• Introduction to Backtracking (Video)
• Backtracking Algorithm (GeeksforGeeks)
• Backtracking Patterns (LeetCode Discussion)