Practice target: Around 75 to 120 minutes daily, with extra time for Hard questions

Week 1: Prefix Sum

Pattern clue: Repeated range totals, left/right sums, or counts of subarrays with a target sum.

Day Topic Exact questions and learning resource
1 Running totals 1480. Running Sum of 1d Array + 1732. Find the Highest Altitude · Beginner guide to prefix sums
2 Query many ranges 303. Range Sum Query - Immutable + 2574. Left and Right Sum Differences
3 Prefix vs suffix 724. Find Pivot Index + 1991. Find the Middle Index in Array
4 Prefix + frequency map 560. Subarray Sum Equals K + 930. Binary Subarrays With Sum
5 2D prefix sums 304. Range Sum Query 2D - Immutable + 1314. Matrix Block Sum · 2D prefix-sum visual explanation
6 Harder subarray sums 974. Subarray Sums Divisible by K + 523. Continuous Subarray Sum
7 Review without hints 303. Range Sum Query - Immutable + 560. Subarray Sum Equals K · Visual algorithm reference

Week 2: Hash Map Lookup and Frequency Counting

Pattern clue: Fast membership lookup, repeated values, or counts of characters and numbers.

Day Topic Exact questions and learning resource
8 Complements 1. Two Sum + 217. Contains Duplicate · Hash table explanation
9 Seen before 2351. First Letter to Appear Twice + 219. Contains Duplicate II
10 Character frequencies 242. Valid Anagram + 383. Ransom Note
11 Position and count 387. First Unique Character in a String + 205. Isomorphic Strings
12 Group by key 49. Group Anagrams + 451. Sort Characters By Frequency
13 Set-based scanning 128. Longest Consecutive Sequence + 347. Top K Frequent Elements
14 Review without hints 1. Two Sum + 49. Group Anagrams · Pattern-based question tracker

Week 3: Two Pointers

Pattern clue: Sorted arrays, symmetric checks, or an in-place scan with two positions.

Day Topic Exact questions and learning resource
15 Converging pointers 125. Valid Palindrome + 344. Reverse String · Algorithm examples with explanations
16 Sorted pair search 167. Two Sum II - Input Array Is Sorted + 977. Squares of a Sorted Array
17 Read/write pointers 283. Move Zeroes + 26. Remove Duplicates from Sorted Array
18 Greedy pointer movement 11. Container With Most Water + 680. Valid Palindrome II
19 Sort and scan 15. 3Sum + 75. Sort Colors
20 Advanced pointer reasoning 42. Trapping Rain Water + 88. Merge Sorted Array
21 Timed review 167. Two Sum II + 11. Container With Most Water + 15. 3Sum

Week 4: Sliding Window

Pattern clue: A contiguous substring or subarray, often longest, shortest, or fixed-size.

Day Topic Exact questions and learning resource
22 Fixed-size window 643. Maximum Average Subarray I + 1343. Number of Sub-arrays of Size K and Average Greater than or Equal to Threshold · Sliding window tutorial
23 Unique-character window 3. Longest Substring Without Repeating Characters + 904. Fruit Into Baskets
24 Find minimum length 209. Minimum Size Subarray Sum + 1493. Longest Subarray of 1's After Deleting One Element
25 Fixed-length frequency window 567. Permutation in String + 438. Find All Anagrams in a String
26 Window with allowed changes 424. Longest Repeating Character Replacement + 1004. Max Consecutive Ones III
27 Stretch problems 76. Minimum Window Substring + 2461. Maximum Sum of Distinct Subarrays With Length K
28 Timed review 3. Longest Substring Without Repeating Characters + 209. Minimum Size Subarray Sum + 424. Longest Repeating Character Replacement · Multi-language worked solutions

Week 5: Binary Search

Pattern clue: Sorted input, first/last valid boundary, or a monotonic answer condition.

Day Topic Exact questions and learning resource
29 Basic search 704. Binary Search + 35. Search Insert Position · Visual binary search guide
30 First true boundary 278. First Bad Version + 374. Guess Number Higher or Lower
31 Range boundaries 34. Find First and Last Position of Element in Sorted Array + 74. Search a 2D Matrix
32 Rotated arrays 33. Search in Rotated Sorted Array + 153. Find Minimum in Rotated Sorted Array
33 Search on answer 162. Find Peak Element + 875. Koko Eating Bananas
34 More search on answer 1011. Capacity To Ship Packages Within D Days + 981. Time Based Key-Value Store
35 Timed review 34. First and Last Position + 33. Search in Rotated Sorted Array + 875. Koko Eating Bananas · Java DSA bootcamp notes

Week 6: Monotonic Stack

Pattern clue: Next greater/smaller element, nearest boundary, or spans across previous values.

Day Topic Exact questions and learning resource
36 Next greater 496. Next Greater Element I + 1475. Final Prices With a Special Discount in a Shop · Reference solutions and explanations
37 Resolve waiting indices 739. Daily Temperatures + 503. Next Greater Element II
38 Streaming spans 901. Online Stock Span + 402. Remove K Digits
39 Histogram boundaries 84. Largest Rectangle in Histogram + 85. Maximal Rectangle
40 Contribution counting 907. Sum of Subarray Minimums + 735. Asteroid Collision
41 Alternate stack approaches 42. Trapping Rain Water + 84. Largest Rectangle in Histogram
42 Timed review 496. Next Greater Element I + 739. Daily Temperatures + 901. Online Stock Span

Week 7: Top K With a Heap