Loop

Backtracking

Systematically exploring all choices with the choose-explore-undo loop.

0 of 6 lessons complete · 144 min total

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  1. Choose, Explore, UndoThe universal template for generating all subsets/permutations/combinations, pruning invalid branches early, and handling duplicates with sort-and-skip. Signal: 'all possible' with n ≤ ~20.Lesson · 16 minNot completed
  2. The Decision Tree GrowsEvery recursive call as a sprouting branch.Animation · 10 minNot completed
  3. Practice: The Big ThreeInclude/exclude subsets, reuse-allowed combinations, and swap-based permutations.medium×33 problems · 0 solvedPractice · 35 minNot completed
  4. Practice: Duplicates & GridsSort-and-skip duplicate handling and grid DFS with visited marking.medium×33 problems · 0 solvedPractice · 35 minNot completed
  5. Practice: Partitions & ConstraintsPrefix partitioning, digit-to-letter mapping, and constraint sets for N-Queens.medium×2hard3 problems · 0 solvedPractice · 40 minNot completed
  6. Backtracking CheckpointTemplate structure, duplicate-skipping conditions, pruning, and complexity of enumeration.Checkpoint · 8 minNot completed