anishfyi.com Upskill DSA Math System design

upskill / 30 days / dsa, math, system design

Upskill

A month is enough when every day has a shape.

This is the sprint: the Blind 75 with answers you rehearse, the math under the code, and every system design question worth reading, ending in one flagship system that is actually mine: Voicer. Answers live on these pages, not behind forty tabs. Progress is saved in your browser, nothing leaves it.

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01The tracks

Three tracks, one flagship

Each track is complete on its own page. Read the answer, close the page, reproduce it. The checkboxes remember what you have cleared.

02The 30 days

August 1 to August 31

The order matters: patterns before trees, estimation before system design, breadth before depth. Redos beat new problems in week four; the misses are the syllabus.

Week 1 · Aug 1 to 7

Foundations

  • DSA: arrays and hashing, two pointers, sliding window (15 problems)
  • Math: Big-O, combinatorics
  • Design: the frame, then all nine building blocks

Week 2 · Aug 8 to 14

Structures

  • DSA: stack, binary search, linked lists, trees (20 problems)
  • Math: probability, bit manipulation
  • Design: the thirteen products, whiteboard two of them cold

Week 3 · Aug 15 to 21

Graphs and money

  • DSA: tries, heap, backtracking, graphs (13 problems)
  • Math: modular arithmetic, estimation
  • Design: marketplaces and infra, whiteboard three, first pass on the flagship

Week 4 · Aug 22 to 31

DP and depth

  • DSA: DP, greedy, intervals, math and geometry, bits (27 problems), then every miss again
  • Design: whiteboard three more, tell the VoicerAI flagship cold, twice
  • Loop: mocks and applications every day
New problem 1 Redo 1 Design read 1 Math module 1 Applications 30 min Total ~3 h

03The loop

What a YC startup actually tests

Early-stage loops are short and practical: they move in days, not months, and every stage rewards evidence you can ship. Train for that, not for a big-tech gauntlet.

Pairing on real code

Practical problems in a shared editor, talking the whole time. The Blind 75 covers the reflexes; narrating the pattern out loud is the skill. Rehearse by saying the approach before you type it.

System design as conversation

Less ceremony than big tech: they want the envelope math, the boxes, and the tradeoff you defend under pushback. The frame plus estimation covers it.

What have you shipped

The stage where the job is won. Lead with Voicer: a real-time system with a latency budget, a state machine, and honest failure modes. One system you own beats ten you memorized.

Where to apply

The direct channel is Work at a Startup: one profile, every hiring YC company. Ten targeted applications a week, each naming the company's actual problem, beats a hundred blasts.