DSA Factory
Curriculum
Level 3 · Structures

Backtracking

About 20 steps, from the first idea to a mastery test.

  1. Stage 0Build, check, undoFree
    1. 1Generate binary strings8 min
    2. 2Generate all subsets9 min
    3. 3Generate valid parentheses9 min
    4. 4Root-to-leaf path sum8 min
  2. Stage 1CombinationsFree
    1. 1Combinations of size k8 min
    2. 2Combination sum, each number once9 min
    3. 3Letter combinations of a phone number8 min
    4. 4Combination sum, numbers can repeat10 min
  3. Stage 2PermutationsFree
    1. 1Every ordering of the items16 min
    2. 2Orderings when values repeat18 min
    3. 3Upper or lower case for each letter12 min
    4. 4Jump straight to the kth ordering16 min
  4. Stage 3Grids and boardsFree
    1. 1Find a word in the grid18 min
    2. 2Queens that never meet22 min
    3. 3Walk over every free square20 min
    4. 4List every route through the maze18 min
  5. Stage 4MasteryFree
    1. 1Cut into palindromes20 min
    2. 2Restore the address20 min
    3. 3Insert operators to reach a target26 min
    4. 4Share the numbers equally26 min
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