Principal+ - 90 Day DSA Roadmap

Use 90-day pacing in the Plan Builder

1. 1
   Days 1–7

   Baseline and language#

   Revisit realistic variants for retention and judgment, review implementation trade-offs, and avoid substituting question volume for confirmed role needs.

   Goals

   • Revisit realistic variants for retention and judgment, review implementation trade-offs, and avoid substituting question volume for confirmed role needs.

   Focus

   concept

   Day 1: Refresh Python interview contractsDay 2: Complexity: name the work you are counting
2. 2
   Days 8–28

   Foundations and core repair#

   Revisit realistic variants for retention and judgment, review implementation trade-offs, and avoid substituting question volume for confirmed role needs.

   Goals

   • Revisit realistic variants for retention and judgment, review implementation trade-offs, and avoid substituting question volume for confirmed role needs.

   Focus

   conceptarrays-hashingtwo-pointersbinary-search

   Day 8: Recursion: make each call's contract explicitDay 9: Correctness: explain why the algorithm must workDay 10: Representation: decide what every value meansDay 11: Arrays & HashingDay 12: Two PointersDay 13: Binary Search
3. 3
   Days 29–49

   Structures and patterns#

   Revisit realistic variants for retention and judgment, review implementation trade-offs, and avoid substituting question volume for confirmed role needs.

   Goals

   • Revisit realistic variants for retention and judgment, review implementation trade-offs, and avoid substituting question volume for confirmed role needs.

   Focus

   linked-listtreesbacktrackinggraphs

   Day 29: Linked ListDay 30: TreesDay 31: BacktrackingDay 32: Graphs
4. 4
   Days 50–64

   Variants and selected extensions#

   Revisit realistic variants for retention and judgment, review implementation trade-offs, and avoid substituting question volume for confirmed role needs.

   Goals

   • Revisit realistic variants for retention and judgment, review implementation trade-offs, and avoid substituting question volume for confirmed role needs.

   Focus

   practiceconcept

   Day 50: Minimum dictionary tokenizationDay 51: Merge timestamped streamsDay 52: Stable Case-Insensitive Label GroupsDay 53: Earliest Longest Unique Event RangeDay 54: Count Signed Target-Sum RangesDay 55: Minimum Ordered Batch CapacityDay 57: Integer arithmetic and coordinate reasoning
5. 5
   Days 65–76

   Mixed and confirmed-format practice#

   Revisit realistic variants for retention and judgment, review implementation trade-offs, and avoid substituting question volume for confirmed role needs.

   Goals

   • Revisit realistic variants for retention and judgment, review implementation trade-offs, and avoid substituting question volume for confirmed role needs.

   Focus

   review

   Day 65: Clarify a changed contract before coding
6. 6
   Days 77–85

   Mocks and targeted recovery#

   Revisit realistic variants for retention and judgment, review implementation trade-offs, and avoid substituting question volume for confirmed role needs.

   Goals

   • Revisit realistic variants for retention and judgment, review implementation trade-offs, and avoid substituting question volume for confirmed role needs.

   Focus

   mockreview

   Day 78: Principal+ - Confirmed-format Coding MaintenanceDay 79: Turn one failure into a regression test
7. 7
   Days 86–90

   Consolidation and buffer#

   Revisit realistic variants for retention and judgment, review implementation trade-offs, and avoid substituting question volume for confirmed role needs.

   Goals

   • Revisit realistic variants for retention and judgment, review implementation trade-offs, and avoid substituting question volume for confirmed role needs.

   Focus

   review

   Day 86: Review and transfer from the mistake logDay 87: Rehearse the final checklist without cramming