30-Day Plan

One focus per day, by pattern. You're on day 1.

1
day
Data Processing
JSON Diet task (redo it clean) · Frequency-array warm-up
today
2
day
Data Processing
CSV Sales Report · Talk through complexity out loud
3
day
Arrays & Hashing
Two Sum (Java + Python) · Valid Anagram
4
day
Arrays & Hashing
Group Anagrams · Top K Frequent Elements
5
day
Two Pointers
Valid Palindrome · Review: two-pointer template
6
day
Two Pointers
3Sum · Duplicate-skipping practice
7
day
Review
Re-solve 2 earlier problems from memory · Flashcards: Complexity + Collections
8
day
Sliding Window
Best Time to Buy/Sell Stock · Sliding-window template
9
day
Sliding Window
Longest Substring w/o Repeating · Explain aloud
10
day
Stack
Valid Parentheses · Stack fundamentals
11
day
Binary Search
Binary Search · Nail the boundaries / off-by-one
12
day
Binary Search
Search in Rotated Array (find on LeetCode) · Review
13
day
Linked List
Reverse Linked List · Merge Two Sorted Lists
14
day
Review
Mock: pick a random solved task, redo timed · Flashcards: Algorithms
15
day
Trees
Invert Binary Tree · Recursion refresh
16
day
Trees
Max Depth of Binary Tree · Same Tree
17
day
Trees
Level Order Traversal (BFS) · DFS vs BFS aloud
18
day
Trees
Validate BST · Review
19
day
Graphs
Number of Islands · Grid DFS/BFS template
20
day
Graphs
Clone Graph · Review
21
day
Backtracking
Subsets · Recall the digital-clock recursion
22
day
Backtracking
Combination Sum · Permutations
23
day
Review
Full mock interview (self-timed, talk aloud) · Flashcards: all topics
24
day
Dynamic Programming
Climbing Stairs · Understand memoization
25
day
Dynamic Programming
House Robber · Coin Change
26
day
Dynamic Programming
Longest Increasing Subsequence · Review
27
day
Data Processing
New CSV/JSON aggregation task · Simulate Toptal format
28
day
System Design (light)
Read: designing a URL shortener · Sketch components
29
day
Mixed
2 random problems, timed · Weak-spot flashcards
30
day
Full Mock
End-to-end mock interview · Review the whole month

The plan advances by number of logged sessions — so it moves at your pace, not the calendar's.