Day 89 — Final revision: your weak list

revision day · weak-list cleanup · blank-file recall

Tonight's goal: empty the course weak list. Re-solve every Notion tracker row where Revision Done is unchecked, then finalize one page of pattern invariants from memory before checking the lessons.

Tonight's protocol

Use Lesson 26 — How to Run a Revision Day for the two-run gate. Borrow the speak-first checkpoint from Lesson 27 — How to Run a Mock / Mixed Day.

0:00-0:03: answer the warm-up MCQs below. Missed answers become weak-list clues, not study time.
0:03-0:05: open the Notion tracker filtered to Revision Done = unchecked. Open a blank file for the first unchecked problem. Solving starts at minute 5.
Each unchecked problem, 0:00-0:02: say the pattern name, invariant, brute force, target time, and target space out loud before typing.
Each unchecked problem, 0:02-0:22: code from a blank file. No notes, no stored code, no hints, no video, no comments section.
Each unchecked problem, 0:22-0:25: run or submit at most twice. Tick Revision Done only if run one or run two passes.
After every failed slot, 2 minutes: leave Revision Done unchecked and write one line: WA: <missed invariant, edge case, or implementation bug>.
Final 20 minutes: write the one-page cheat sheet from memory first: arrays, strings/windows, stack, linked list, trees, heap, graphs, DP, and any system-design gate you failed. Then check the relevant lessons and correct only wrong or missing invariant lines.

The problem menu

Your actual menu is the tracker filter: every unchecked course problem must be re-solved. Use this link table only to open the exact unchecked row and confirm its pattern name.

Block	Problem	Pattern name
Arrays	Two Sum	Hashing / seen question
Arrays	Best Time to Buy and Sell Stock	Greedy min-tracking
Arrays	Contains Duplicate	Hashing / seen question
Arrays	Maximum Subarray	Kadane's algorithm
Arrays	Product of Array Except Self	Prefix × suffix products
Arrays	Move Zeroes	Two pointers, same direction
Arrays	Merge Sorted Array	Two pointers, converging
Arrays	Majority Element	Boyer-Moore majority vote
Arrays	Missing Number	XOR cancellation
Arrays	Find Pivot Index	Prefix sums
Arrays	Range Sum Query - Immutable	Prefix sums
Strings/window	Valid Anagram	Frequency Counting
Strings/window	Valid Palindrome	Two Pointers on Strings
Strings/window	Longest Substring Without Repeating Characters	Sliding Window I: The Shrinking Rule
Strings/window	Longest Repeating Character Replacement	Sliding Window II: Validity With a Budget
Strings/window	Minimum Window Substring	Sliding Window III: Minimum Window
Strings/window	Group Anagrams	Frequency Counting
Stack	Valid Parentheses	Stack matching
Stack	Min Stack	Shadow minima stack
Stack	Daily Temperatures	Monotonic stack: next warmer
Stack	Next Greater Element I	Monotonic stack: next greater
Stack	Largest Rectangle in Histogram	Monotonic stack: finalize on shorter bar
Stack	Evaluate Reverse Polish Notation	Stack evaluation
Linked list	Reverse Linked List	prev/curr/next
Linked list	Merge Two Sorted Lists	The dummy node trick
Linked list	Linked List Cycle	Floyd's fast/slow pointers
Linked list	Remove Nth Node From End of List	Gap Pointers: n Apart
Linked list	Reorder List	Composing Linked-List Primitives
Linked list	Copy List with Random Pointer	Cloning with a map
Trees	Inorder Traversal	Recursive inorder traversal
Trees	Maximum Depth	Tree recursion with return value
Trees	Same Tree	Simultaneous DFS / lockstep comparison
Trees	Level Order Traversal	BFS levels with queue snapshot
Trees	Diameter of Binary Tree	Piggyback on height
Trees	Balanced Binary Tree	Piggyback on height
Trees	Lowest Common Ancestor	Tree recursion: split under the current node
Trees	Binary Tree Right Side View	BFS levels: queue-length snapshot, keep the last node
Trees	Serialize and Deserialize Binary Tree	Preorder plus explicit null markers
Trees	Path Sum	DFS paths: carry the remaining sum
Trees	Construct Binary Tree from Preorder and Inorder	Preorder root plus inorder split with hashmap
Heap	Kth Largest Element	Heap top-k
Heap	Top K Frequent Elements	Heap top-k by frequency
Heap	Merge K Sorted Lists	K-way merge heap
Heap	Find Median from Data Stream	Two heaps
Heap	Task Scheduler	Heap scheduling with cooldown
Graphs	Number of Islands	grid DFS / flooding a grid
Graphs	Clone Graph	graph cloning / cloning with a map
Graphs	Course Schedule	topological sort / prerequisites and cycles
Graphs	Pacific Atlantic Water Flow	reverse flood fill / search backwards
Graphs	Word Ladder	implicit graph BFS
Graphs	Network Delay Time	Dijkstra / BFS with weights
DP	Climbing Stairs	DP four questions
DP	House Robber	take-or-skip DP
DP	Coin Change	unbounded minimum DP
DP	Longest Increasing Subsequence	ending-at-i DP state
DP	Partition Equal Subset Sum	0/1 knapsack reachable sums
DP	Longest Common Subsequence	2D DP: two strings, one grid
DP	Edit Distance	Two-string DP: insert, delete, replace
DP	Decode Ways	Counting DP with validity constraints
DP	Word Break	Segmentable prefixes
DP	Burst Balloons	Interval DP: choose the last action

Warm-up MCQs

1. When does Day 89 revision credit count?

2. Which move starts each timed slot correctly?

3. Which invariant fits a seen-question problem?

4. What repairs a broken sliding window?

5. When a monotonic stack pops, what happened?

6. Which checklist belongs before DP code?

Self-check gate

Pass tonight only if

The Notion filter Revision Done = unchecked is empty for course problems, because every weak row passed from a blank file on run one or run two.
Every failed gate has either been passed tonight or still has a fresh WA: <root cause> note and remains unchecked.
The one-page cheat sheet was written from memory before checking lessons, and every corrected invariant is now in your own words.

Failure path: if any row fails after two runs, do not tick Revision Done. Keep that exact problem unchecked, put it first in the next revision slot, and ask your teacher with the problem link, your invariant sentence, the failing code, and the WA note.