Recursion Basics
Base case, recursive case, call stack.
Tail Recursion
Recursive call as final operation.
Backtracking Introduction
Explore, choose, unchoose pattern.
Permutations
Generate all permutations.
Combinations
Generate k-combinations from n elements.
Subsets
Power set generation.
N-Queens
Place N queens on N×N board.
Sudoku Solver
Constraint satisfaction with backtracking.
Word Search
Grid DFS with backtracking.
Generate Parentheses
Valid parentheses combinations.