mock day · 60 minutes · three DSA problems · calm finish
Tonight's goal: run one final 60-minute mock across the course, review your pattern cheat sheet once, then score against Day 30 and Day 60. You have done 90 days of deliberate work — walk in calm.
Tonight's protocol
Use the mock-day protocol: strict timer, approach and complexity out loud, code second, compare after.
0:00-0:03 — Warm up: answer the six MCQs below. If one misses, read only its invariant quote and keep moving.
0:03-0:05 — Setup: open one blank file and the three LeetCode tabs. Do not open notes, hints, saved code, videos, or solution text.
0:05-0:25 — Problem 1: say the pattern, brute force, better approach, time, and space out loud; then code.
0:25-0:45 — Problem 2: repeat the same spoken checkpoint. If stuck after 14 minutes in the slot, read only the pattern name from the menu.
0:45-1:05 — Problem 3: repeat the same rule. Stop when the timer ends; do not borrow time from review.
1:05-1:15 — Cheat sheet pass: read your pattern cheat sheet once, top to bottom. Add no new material during this pass.
1:15-1:20 — Score: give each problem 1 for accepted, 0.5 for right invariant with unfinished code, and 0 for wrong direction. Compare the total with Day 30 and Day 60.
The problem menu
Run exactly these three problems. Each slot is 20 minutes. Explain aloud before typing.
Source invariant: “Under a strict timer, state your approach and its complexity out loud before you write a line of code — the talking is the skill being tested.”
2. The timer hits a stuck checkpoint. What should you read?
Source invariant: “Under a strict timer, state your approach and its complexity out loud before you write a line of code — the talking is the skill being tested.”
3. When does a failed problem leave the revision queue?
Source invariant: “Re-solve your weakest problems from a blank file with no hints; a problem only counts as revised when it compiles and passes on the first or second run.”
4. Find Pivot Index: what replaces re-summing both sides?
Source invariant: “Precompute a running total once, then answer any range or split in O(1).”
5. Number of Islands: what starts a new component?
Source invariant: “DFS floods everything reachable in one component; count how many times you must start a new flood. The grid itself is the adjacency list — mark visited in place.”
6. Coin Change: what does the transition minimize?
Source invariant: “dp[amount] = 1 + the minimum of dp[amount - coin] over every coin; amounts you can never make stay infinite.”
Self-check gate
Pass bar
The first LeetCode attempt started by minute 5.
All three problems stayed inside their 20-minute boxes.
Before each problem, you said the pattern, brute force, better approach, time, and space out loud.
No solution text opened during the 60-minute timer.
Your final score compares tonight's 0-3 total with Day 30 and Day 60.
Failure path: add every failed or unclear problem to the next revision list with WA: <missed invariant or implementation bug>. Re-solve it from a blank file with no hints, using the revision-day protocol.