📚 LeetCode Study Log — 2026 Goal: Build pattern recognition through systematic practiceStudy Pace: 3–10 problems/dayMentor Review: WeeklyFocus: Python3 + SQLCurrent Phase: 🔄 Review Month (post-💯 milestone — see "What's Next" at the bottom)
Day
Date
Easy
Medium
Hard
Category
Status
Day 1
05/15
7
4
0
Arrays, Hash Map, Sorting, Backtracking
✅ Complete
Day 2 (Makeup)
05/16
6
1
0
Sorting, Brute Force
✅ Complete
Day 3
05/15
2
2
0
DFS/Trees
✅ Complete
Day 4A
05/16
4
2
1
SQL/MySQL
✅ Complete
Day 4B
05/16
2
1
0
Matrix Traversal
✅ Complete
Day 5
05/18
3
3
0
Greedy Algorithm
✅ Complete
Day 6
05/19
2
1
0
Hash Map / Hash Set
✅ Complete
(Gap: final exams + app projects) 05/20–06/03
—
—
—
Returned 6/4 — honest log
📝 Noted
Day 8
06/04
18
2
0
Mixed (DP, Bit, Prefix Sum, Matrix, SQL, Simulation)
✅ Complete
Day 9
06/05
7
3
0
Strings + Tree DFS
✅ Complete
Day 10
06/07
4
1
0
Hash Table Family
✅ Complete
Day 11 ⭐
06/09
6
2
1
Sorting + DP (4 flavors) + Hash Table
✅ Complete
Day 12 ⭐
06/10
4
1
0
Linked List + Simulation + Graph + Math
✅ Complete
Day 13 ⭐⭐
06/14
0
9
1
Greedy + Tree + DP + Math (10 Mediums/Hards)
✅ 💯 MILESTONE
🟢 Easy: 65
🟡 Medium: 32
🔴 Hard: 3
Total: 100 ✅
🎯 100 problems reached on June 14, 2026. Now entering Review Month — see "What's Next" at the bottom.
Last active day: Day 13 (06/14) — 10-problem marathon (9 Mediums + 1 Hard) culminating in the 💯 milestonePatterns owned: Hash Map / Hash Set / Hash Table (8+ sub-patterns), Sorting (5+ sub-patterns), Two Pointers, Binary Search, Backtracking, Sliding Window basics, Dynamic Programming (7 sub-patterns ), Tree DFS (5 flavors), Tree BFS (level-aware + deepest-overwrite) , Mirror DFS , N-ary DFS , Linked List (traversal, immutable reverse, sqrt(n) decomp), Graph (adjacency matrix), Greedy (matrix cap, stack construction, sort+pair, sort+triplet), Bit Manipulation (multiple), Prefix Sum, Counting Sort, Matrix Diagonal, Subset Bitmask, Permutation Frequency Trick, Manhattan Distance, Sparse Representation, Class Design, Catalan Numbers , Stars and Bars , Frobenius Number , Mathematical Collapse (3 instances), Stateless map → sum (9+ encounters), SQL (JOIN, GROUP BY DISTINCT, CROSS JOIN, Window Functions, Anti-Join, Recursive CTE)Languages: Python3, SQL/MySQL
DAY 1 | May 15, 2026 | 11 Problems (7 Easy + 4 Medium)
#
Title
Pattern
Date
Link
1
Two Sum
Hash Map
2026-05-15
View ✅
14
Longest Common Prefix
String
2026-05-15
View ✅
26
Remove Duplicates
Two Pointers
2026-05-15
View ✅
27
Remove Element
Two Pointers
2026-05-15
View ✅
35
Search Insert Position
Binary Search
2026-05-15
View ✅
66
Plus One
Array/Math
2026-05-15
View ✅
88
Merge Sorted Array
Two Pointers
2026-05-15
View ✅
#
Title
Pattern
Date
Link
11
Container with Most Water
Greedy/TP
2026-05-15
View ✅
15
Three Sum
Two Pointers
2026-05-15
View ✅
39
Combination Sum
Backtracking
2026-05-15
View ✅
46
Permutations
Backtracking
2026-05-15
View ✅
DAY 2 | May 15-16, 2026 | 6 Problems (4 Easy + 2 Medium)
#
Title
Pattern
Date
Link
905
Transform Array by Parity
Sorting
2026-05-15
View ✅
1679
Count Pairs Sum < Target
Sorting
2026-05-15
View ✅
2050
Count Numbers Unique Digits
Brute Force
2026-05-15
View ✅
2418
Sort the People
Sorting/Hash Map
2026-05-15
View ✅
#
Title
Pattern
Date
Link
2541
Min Cost Split into Ones
DP
2026-05-15
View ✅
2545
Sort Students by Kth Score
Sorting
2026-05-15
View ✅
DAY 3 | May 15-16, 2026 | 4 Problems (2 Easy + 2 Medium)
#
Title
Pattern
Date
Link
938
Range Sum of BST
Trees/DFS
2026-05-15
View ✅
1379
Find Corresponding Node in Clone
Trees/DFS
2026-05-15
View ✅
#
Title
Pattern
Date
Link
1038
BST to Greater Sum Tree
Trees/DFS
2026-05-15
View ✅
2265
Count Nodes Equal to Average
Trees/DFS
2026-05-15
View ✅
DATABASE SESSION | May 16, 2026 | 7 Problems (4 Easy + 2 Medium + 1 Hard)
#
Title
Pattern
Date
Link
1350
Students Invalid Departments
JOIN/Anti-join
2026-05-16
View ✅
1303
Find Team Size
Window Functions
2026-05-16
View ✅
1757
Recyclable and Low Fat
WHERE/AND
2026-05-16
View ✅
1571
Warehouse Manager
JOIN/GROUP BY
2026-05-16
View ✅
#
Title
Pattern
Date
Link
3204
Bitwise User Permissions
Bitwise/Aggregate
2026-05-16
View ✅
2989
Class Performance
Calculation
2026-05-16
View ✅
#
Title
Pattern
Date
Link
3368
First Letter Capitalization
Recursive CTE
2026-05-16
View ✅
MATRIX SESSION | May 16, 2026 | 3 Problems (2 Easy + 1 Medium)
#
Title
Pattern
Date
Link
1672
Richest Customer Wealth
Row Sum/Max
2026-05-16
View ✅
2373
Largest Local Values
Sliding Window
2026-05-16
View ✅
#
Title
Pattern
Date
Link
885
Spiral Matrix III
Simulation/Spiral
2026-05-16
View ✅
Day 5 | May 18, 2026 | 6 Greedy Problems (3 Easy + 3 Medium)
#
Title
Pattern
Date
Link
1221
Split a String in Balanced Strings
Balance Tracking
2026-05-18
View ✅
2037
Seat Everyone
Sort + Pair
2026-05-18
View ✅
2160
Minimum Sum Four Digits
Digit Placement
2026-05-18
View ✅
#
Title
Pattern
Date
Link
1689
Partitioning Deci-Binary
Max Digit Insight
2026-05-18
View ✅
1874
Minimize Product Sum
Pair Opposites
2026-05-18
View ✅
1282
Group People by Size
Bucket + Split
2026-05-18
View ✅
Day 6 | May 19, 2026 | 3 Problems (2 Easy + 1 Medium)
#
Title
Pattern
Date
Link
1512
Number of Good Pairs
Hash Map / Counting
2026-05-19
View ✅
3668
Restore Finishing Order
Hash Set / Filter
2026-05-19
View ✅
#
Title
Pattern
Date
Link
3760
Maximum Substrings With Distinct Start
Hash Set / Distinct Count
2026-05-19
View ✅
Day 8 | June 4, 2026 | 20 Problems (18 Easy + 2 Medium) — Resumed after exam-week gap
Catch-up session. Took a 2-week break for finals + capstone polish + LinkedIn launch. Resumed with deliberate "variety + volume" run.
Easy — DP / Bit Manipulation (2)
#
Title
Pattern
Date
Link
70
Climbing Stairs
DP / Fibonacci
2026-06-04
View ✅
338
Counting Bits
DP / Bit Manipulation
2026-06-04
View ✅
Easy — Sorting / Greedy (3)
#
Title
Pattern
Date
Link
349
Intersection of Two Arrays
Two Pointers / Hash Set
2026-06-04
View ✅
561
Array Partition
Greedy / Sorting
2026-06-04
View ✅
1051
Height Checker
Sorting / Counting Sort
2026-06-04
View ✅
#
Title
Pattern
Date
Link
1863
Sum of All Subset XOR Totals
Bit Manipulation / Subset Enum
2026-06-04
View ✅
2843
Count Symmetric Integers
Enumeration / Digit Manipulation
2026-06-04
View ✅
#
Title
Pattern
Date
Link
1572
Matrix Diagonal Sum
Matrix / Diagonal Indexing
2026-06-04
View ✅
#
Title
Pattern
Date
Link
1480
Running Sum of 1d Array
Prefix Sum
2026-06-04
View ✅
2574
Left and Right Sum Differences
Prefix Sum / Two Pass
2026-06-04
View ✅
#
Title
Pattern
Date
Link
1821
Find Customers With Positive Revenue This Year
SQL / WHERE Filter
2026-06-04
View ✅
2339
All the Matches of the League
SQL / CROSS JOIN
2026-06-04
View ✅
2356
Number of Unique Subjects Taught by Each Teacher
SQL / GROUP BY + COUNT DISTINCT
2026-06-04
View ✅
Easy — Bit Manipulation (3)
#
Title
Pattern
Date
Link
1684
Count the Number of Consistent Strings
Bit Manipulation / Set Membership
2026-06-04
View ✅
2220
Minimum Bit Flips to Convert Number
Bit Manipulation / XOR + Popcount
2026-06-04
View ✅
3173
Bitwise OR of Adjacent Elements
Bit Manipulation / Array Traversal
2026-06-04
View ✅
#
Title
Pattern
Date
Link
1920
Build Array from Permutation
Simulation / In-Place Bit Packing
2026-06-04
View ✅
2011
Final Value of Variable After Performing Operations
Simulation / String Inspection
2026-06-04
View ✅
#
Title
Pattern
Date
Link
2084
Drop Type 1 Orders for Customers With Type 0 Orders
SQL / Anti-Join + Window Function
2026-06-04
View ✅
Medium — Hash / Bit Manipulation (1)
#
Title
Pattern
Date
Link
2657
Find the Prefix Common Array of Two Arrays
Hash / Permutation Frequency Trick
2026-06-04
View ✅
Day 9 | June 5, 2026 | 10 Problems (7 Easy + 3 Medium) — Strings + Tree DFS
#
Title
Pattern
Date
Link
1119
Remove Vowels from a String
String / Filter / Set Membership
2026-06-05
View ✅
2942
Find Words Containing Character
String / Indexed Filter
2026-06-05
View ✅
3110
Score of a String
String / Adjacent Pair Aggregation
2026-06-05
View ✅
#
Title
Pattern
Date
Link
94
Binary Tree Inorder Traversal
Tree / DFS / Iterative Stack
2026-06-05
View ✅
100
Same Tree
Tree / Parallel DFS
2026-06-05
View ✅
104
Maximum Depth of Binary Tree
Tree / DFS Aggregation
2026-06-05
View ✅
226
Invert Binary Tree
Tree / DFS Mutation
2026-06-05
View ✅
#
Title
Pattern
Date
Link
1769
Minimum Operations to Move All Balls to Each Box
String / Two-Pass Prefix Sum
2026-06-05
View ✅
3846
Total Distance to Type a String Using One Finger
String / Hash Map / Manhattan
2026-06-05
View ✅
#
Title
Pattern
Date
Link
1382
Balance a Binary Search Tree
Tree / Inorder + Divide & Conquer Rebuild
2026-06-05
View ✅
Day 10 | June 7, 2026 | 5 Problems (4 Easy + 1 Medium) — Hash Table Family Easy — Hash Table Variants (4)
#
Title
Pattern
Date
Link
771
Jewels and Stones
Hash Table / Set Membership
2026-06-07
View ✅
3289
The Two Sneaky Numbers of Digitville
Hash Table / Increment-Then-Check
2026-06-07
View ✅
3541
Find Most Frequent Vowel and Consonant
Hash Table / Counter / Conditional Max
2026-06-07
View ✅
3945
Digit Frequency Score
Hash Table / Counter / Digit
2026-06-07
View ✅
Medium — Class Design (1)
#
Title
Pattern
Date
Link
1570
Dot Product of Two Sparse Vectors
Hash Table / Sparse / Class Design
2026-06-07
View ✅
Day 11 | June 9, 2026 | 9 Problems (6 Easy + 2 Medium + 1 Hard) — Sorting + DP Sweep ⭐
#
Title
Pattern
Date
Link
1365
How Many Numbers Are Smaller Than the Current Number
Sorting / Counting Sort + Prefix Sum
2026-06-09
View ✅
1637
Widest Vertical Area Between Two Points Containing No Points
Sorting / Dimensional Reduction / Adjacent Pair
2026-06-09
View ✅
3667
Sort Array By Absolute Value
Sorting / Custom Key
2026-06-09
View ✅
#
Title
Pattern
Date
Link
3146
Permutation Difference between Two Strings
Hash Table / Position Lookup
2026-06-09
View ✅
3450
Maximum Students on a Single Bench
Hash Table / Group-By + Set per Group
2026-06-09
View ✅
Medium — Dynamic Programming (2)
#
Title
Pattern
Date
Link
894
All Possible Full Binary Trees
DP / Tree Construction / Catalan Numbers ⭐
2026-06-09
View ✅
1277
Count Square Submatrices with All Ones
DP / 2D Grid DP ⭐
2026-06-09
View ✅
#
Title
Pattern
Date
Link
3751
Total Waviness of Numbers in Range I
DP / Digit DP ⭐
2026-06-09
View ✅
Hard — Dynamic Programming (1)
#
Title
Pattern
Date
Link
1255
Maximum Score Words Formed by Letters
DP / Bitmask Subset Enumeration ⭐
2026-06-09
View ✅
Day 12 | June 10, 2026 | 5 Problems (4 Easy + 1 Medium) — Linked List + Graph + Math ⭐
#
Title
Pattern
Date
Link
3263
Convert Doubly Linked List to Array I
Linked List / Traversal Template ⭐ first LL
2026-06-10
View ✅
#
Title
Pattern
Date
Link
3687
Library Late Fee Calculator
Simulation / Tiered Piecewise / Stateless Map → Sum
2026-06-10
View ✅
#
Title
Pattern
Date
Link
1265
Print Immutable Linked List in Reverse
Linked List / Recursion + Stack + sqrt(n) ⭐
2026-06-10
View ✅
#
Title
Pattern
Date
Link
3898
Find the Degree of Each Vertex
Graph / Adjacency Matrix / Row Sum ⭐ first Graph
2026-06-10
View ✅
#
Title
Pattern
Date
Link
3512
Minimum Operations to Make Array Sum Divisible by K
Math / Modular Arithmetic / Mathematical Collapse
2026-06-10
View ✅
Day 13 | June 14, 2026 | 10 Problems (9 Medium + 1 Hard) — 💯 MILESTONE ⭐⭐
The 100-problem milestone day. Started with three Greedy Mediums showcasing exchange arguments; pivoted to tree problems for the back half (BFS level-aware, BFS deepest-overwrite, DFS mirror recursion, N-ary DFS); closed with a Hard (state-compression DP) and two math-collapse Mediums (Frobenius, Stars and Bars). Every problem introduced a new template or sub-pattern.
#
Title
Pattern
Date
Link
807
Max Increase to Keep City Skyline
Greedy / Matrix / Two-Constraint Cap
2026-06-14
View ✅
2375
Construct Smallest Number From DI String
Greedy / Active Stack ⭐ first active stack
2026-06-14
View ✅
1561
Maximum Number of Coins You Can Get
Greedy / Sort + Take Every Other (triplets)
2026-06-14
View ✅
#
Title
Pattern
Date
Link
3831
Median of a Binary Search Tree Level
Tree BFS / Level-Aware Traversal ⭐ first BFS
2026-06-14
View ✅
2415
Reverse Odd Levels of Binary Tree
Tree DFS / Mirror Recursion ⭐ first mirror DFS
2026-06-14
View ✅
1302
Deepest Leaves Sum
Tree BFS / Deepest-Level Overwrite
2026-06-14
View ✅
Medium — Nested Structure DFS
#
Title
Pattern
Date
Link
339
Nested List Weight Sum
N-ary DFS / Structural Recursion ⭐ first N-ary
2026-06-14
View ✅
Hard — Dynamic Programming (1) ⭐ 2nd algorithmic Hard
#
Title
Pattern
Date
Link
1411
Number of Ways to Paint N×3 Grid
DP / State Compression ⭐ 7th DP sub-pattern
2026-06-14
View ✅
Medium — Math Collapse (2)
#
Title
Pattern
Date
Link
2979
Most Expensive Item That Can Not Be Bought
Math / Frobenius (Chicken McNugget)
2026-06-14
View ✅
1641
Count Sorted Vowel Strings 💯
Math / Stars and Bars
2026-06-14
View ✅
🧩 Pattern Summary (Cumulative 100)
Pattern
Count
Hash Map / Hash Set / Hash Table (8+ sub-patterns)
12
Sorting (5+ sub-patterns)
10
Two Pointers
5
Binary Search
1
Backtracking
2
Dynamic Programming (7 sub-patterns) 8
Bit Manipulation (multiple)
5
Greedy (matrix cap, stack, sort+pair, sort+triplet)
9
Prefix Sum (1D, 2D, two-pass)
3
Counting Sort
1
Tree DFS (5 flavors)
7
Tree BFS (level-aware + deepest-overwrite) ⭐2
Mirror DFS ⭐1
N-ary DFS / Structural Recursion ⭐1
Linked List (3 sub-patterns)
3
Graph / Adjacency Matrix ⭐1
Math / Modular Collapse
3
Math / Frobenius
1
Math / Stars and Bars
1
Catalan Numbers
1
Simulation (multiple)
4
Matrix (row sum, sliding window, spiral, diagonal)
4
String (multiple)
5
SQL (7 sub-patterns)
10
Brute Force / Enumeration
2
Array/Math
1
Total 100
Day 1-2: Arrays & Sorting
Hash map for O(n) lookups
Two-pointer technique for sorted arrays
Sorting with custom keys
Greedy algorithms
Post-order traversal for subtree aggregation
Tuple returns (sum, count) pattern
Parallel tree traversal
BST properties for optimization
Database (Day 4A): SQL Patterns
Aggregate functions (BIT_AND, BIT_OR, COUNT, MAX, MIN)
Anti-join pattern (LEFT JOIN + IS NULL)
Window functions (PARTITION BY)
Recursive CTE
String manipulation with REGEXP
Matrix Session (Day 4B): Traversal Patterns
Row sum and max finding
2D sliding window (3×3)
Spiral traversal with direction vectors
(Day 8) Diagonal indexing
Max digit = bottleneck (deci-binary)
Pair opposites, balance tracking
Sorting for optimal assignment
Digit placement, bucket + greedy filling
Day 6: Hash-Based Counting
Streaming hash map for pair counting
Set membership for filter-preserving-order
Distinct-count collapse
Day 8: Multi-Pattern Recovery (20 problems)
DP / Fibonacci two-variable rolling
Bit Manipulation DP, XOR + popcount
Bitmask as set (26-bit integer = lowercase letter set)
Greedy pairing, counting sort O(n + R)
Permutation frequency trick (LC 2657)
Store-before-update prefix sum
Bit-packing for O(1) space (LC 1920)
Day 9: Strings + Tree DFS Toolkit (10 problems)
Adjacent-pair template zip(seq, seq[1:])
Filter pattern, never += strings in loop (O(n²))
Two-pass directional sweep (LC 1769)
Manhattan distance + position lookup (LC 3846)
Tree DFS Four Flavors: list (LC 94), compare (LC 100), aggregate (LC 104), mutate (LC 226)Two-phase pattern (LC 1382): inorder → sorted → rebuild
Overflow-safe start + (end - start) // 2
Day 10: Hash Table Deep Dive (5 problems)
5 distinct shades of hash-table usage
First OOP / class design (LC 1570 Sparse Vector)
max(default=0) idiom
Day 11: Sorting + DP Sweep ⭐ (9 problems, 4 DP flavors)
Sorting toolkit: dimensional reduction (LC 1637), custom key (LC 3667), counting sort + prefix (LC 1365)
4 DP sub-patterns introduced: Digit DP (LC 3751), Catalan/structural (LC 894), Bitmask subset (LC 1255 — Hard), 2D Grid (LC 1277)Constraint-recognition meta-skill table
"DP cell = direct answer per cell" trick (LC 1277)
Day 12: Linked List + Graph + Math ⭐
LL traversal template while curr: ... curr = curr.next
LC 1265 sqrt(n) decomposition gem
First Graph: adjacency matrix = special-purpose 2D array
First math collapse (LC 3512): sum(nums) % k
Tree DFS = linear tree DFS without branching
Day 13: 100-Problem Marathon ⭐⭐ (10 problems) Three Greedy Mediums (exchange-argument provable):
LC 807: Two-constraint cap (matrix); zip(*grid) transpose
LC 2375: First active stack algorithm (push/flush template)
LC 1561: Sort + sacrifice triplets (LC 561 generalized)
Three Tree problems (toolkit completion):
LC 3831: First level-aware BFS (size = len(queue) snapshot)
LC 2415: First mirror DFS — (left.left, right.right), (left.right, right.left)
LC 1302: Deepest-level BFS via "overwrite each level" trick
One N-ary DFS:
LC 339: Structural recursion; binary DFS generalizes to N-ary
One Hard — 7th DP sub-pattern:
LC 1411: Row-pattern state-compression DP . 12 patterns → 2 equivalence classes (ABA, ABC) via color symmetry. O(n) recurrence with aba, abc tuple update.
Two Math Collapses (closing the trifecta):
LC 2979: Chicken McNugget Theorem — p₁·p₂ - p₁ - p₂ for coprime
LC 1641 (💯): Stars and Bars — C(n + 4, 4)
The Math Collapse Trifecta (cumulative)
Problem
Hidden Math
Closed Form
LC 3512 (Day 12)
Modular arithmetic
sum % k
LC 2979 (Day 13)
Frobenius / McNugget
p₁·p₂ - p₁ - p₂
LC 1641 (Day 13)
Stars and bars
C(n + 4, 4)
Lesson: small constraints + "counting" framing → check for closed combinatorial form FIRST.
DP Sub-Pattern Toolkit (7 patterns)
Sub-pattern
Day
Example
Linear / Fibonacci
8
LC 70
Bit DP
8
LC 338
Digit DP
11
LC 3751
Structural / Catalan
11
LC 894
Bitmask Subset
11 (Hard)
LC 1255
2D Grid
11
LC 1277
Row-Pattern State Compression 13 (Hard)
LC 1411
Template
Day
Example
DFS list traversal (iterative)
9
LC 94
DFS parallel two-tree
9
LC 100
DFS aggregation
9
LC 104
DFS mutation
9
LC 226
DFS inorder + rebuild
9
LC 1382
Mirror DFS 13
LC 2415
Level-aware BFS 13
LC 3831
Deepest-level BFS (overwrite) 13
LC 1302
N-ary DFS 13
LC 339
Cumulative recurring idioms
"Stateless map → sum" (9+ encounters): sum(f(x) for x in items)Adjacent-pair zip(seq, seq[1:]) (7+ encounters)Constraint-recognition meta-skill table (Day 11)Tuple swap a, b = b, a (LC 226, LC 1411, LC 2415)max(default=0) for safe empty-iterable maxExchange argument for greedy correctness (Day 13 × 3)
Each problem file includes:
✅ Understanding the Goal
✅ LAYER 1: Line-by-line code (heavy inline comments)
✅ LAYER 2: Worked examples with traces
✅ LAYER 3: Key insights & complexity
✅ LAYER 4: Interview variations
✅ LAYER 5: Cheat sheet entry
🎯 What's Next — Review Month (post-💯) Phase shift: going from "add new patterns" to "lock in the existing 100." Goal: a sustained month of review-focused work with continued (slower) problem-solving. See how many MORE problems fit in alongside review.
Spaced Repetition (Week 1: 6/15 – 6/21) Re-derive without looking — write the template from scratch:
Mirror DFS (LC 2415): (left.left, right.right), (left.right, right.left)
Level-aware BFS (LC 3831): size = len(queue) snapshot
Deepest-level BFS overwrite (LC 1302)
Push/flush stack (LC 2375)
Two-constraint cap (LC 807)
Bitmask subset enumeration (LC 1255)
State-compression DP (LC 1411): aba, abc = (3a + 2b), (2a + 2b)
Digit DP framework (LC 3751)
Re-derive math collapses:
Modular collapse: sum % k
Frobenius: m·n - m - n for coprime
Stars and bars: C(n + k - 1, k - 1)
Re-solve 2-3 problems per pattern family from scratch. Timed, no peeking.
Identify Weak Spots (Week 2: 6/22 – 6/28) Patterns with thin coverage:
Linked List Mediums — only 1 (LC 1265). Pending: LC 206, LC 876, LC 21 locks in the LL trifecta (reverse, slow/fast, merge with dummy).Heap / Priority Queue — still 0 . Add via LC 215 (k-th largest), LC 703 (streaming median).Graph BFS/DFS — adjacency matrix only (LC 3898). Build adjacency list and traverse via LC 1971 (path exists), LC 200 (number of islands).Sliding Window — basics covered; add explicit problems like LC 3 (longest substring without repeating), LC 209 (min subarray sum ≥ target).Binary Search depth — only LC 35 (Day 1). Add LC 33 (rotated sorted), LC 153 (find min).
Mock Interview Sessions (Week 3-4: 6/29 onward) 45-min sessions on a random Medium with these rules:
Verbalize the approach BEFORE coding (5 min)
Code the solution (25 min)
Test against examples and edge cases (10 min)
Optimize if time (5 min)
Time pressure forces template reflexes . The goal isn't "solve everything" — it's making sure that under stress, the templates from the past month are accessible.
Continued Practice (alongside review) Target pace: 1-3 problems per day. Mix:
60% review (re-solve, re-derive, drill weak spots)
40% new (Easies and Mediums from weak categories)
By 6/14/2026 + 30 days = 7/14/2026: aim for ~130-150 problems, with strong active recall on all 100 baseline.
Stretch Goals for the Month
Hit 150 problems total with no template loss
5+ Hard problems total (currently 3)Cover the 4 weak-spot categories above (LL Mediums, Heap, Graph BFS, Sliding Window)
Complete a mock interview gauntlet: 10 timed Mediums in a week without looking up patterns
Last Updated: June 14, 2026 | 100 Problems Solved ✅
The journey from LC 1 Two Sum (May 15) to LC 1641 Count Sorted Vowel Strings (June 14): 30 days, 13 active sessions, 100 problems, ~25 distinct pattern families, 7 DP sub-patterns, a complete tree toolkit (DFS × 5 + BFS × 2 + mirror DFS + N-ary), the math collapse trifecta, and reflexive pattern composition.
Now: review. Then more. 🚀