Grokking the coding interview equivalent leetcode problems

grokking_to_leetcode.md

GROKKING NOTES

I liked the way Grokking the coding interview organized problems into learnable patterns. However, the course is expensive and the majority of the time the problems are copy-pasted from leetcode. As the explanations on leetcode are usually just as good, the course really boils down to being a glorified curated list of leetcode problems.

So below I made a list of leetcode problems that are as close to grokking problems as possible.

Pattern: Sliding Window

• https://leetcode.com/problems/maximum-subarray/ # Close enough
• https://leetcode.com/problems/minimum-size-subarray-sum/
• https://leetcode.com/problems/longest-substring-with-at-most-k-distinct-characters/
• https://leetcode.com/problems/fruit-into-baskets/
• https://leetcode.com/problems/longest-substring-without-repeating-characters/
• https://leetcode.com/problems/longest-repeating-character-replacement/
• https://leetcode.com/problems/max-consecutive-ones-iii/
• https://leetcode.com/problems/permutation-in-string/
• https://leetcode.com/problems/find-all-anagrams-in-a-string/
• https://leetcode.com/problems/minimum-window-substring/
• https://leetcode.com/problems/substring-with-concatenation-of-all-words/

Pattern: Two Pointers

• https://leetcode.com/problems/two-sum/
• https://leetcode.com/problems/remove-duplicates-from-sorted-array/
• https://leetcode.com/problems/squares-of-a-sorted-array/
• https://leetcode.com/problems/3sum/
• https://leetcode.com/problems/3sum-closest/
• https://leetcode.com/problems/3sum-smaller/
• https://leetcode.com/problems/subarray-product-less-than-k/
• https://leetcode.com/problems/sort-colors/
• https://leetcode.com/problems/4sum/
• https://leetcode.com/problems/backspace-string-compare/
• https://leetcode.com/problems/shortest-unsorted-continuous-subarray/

Pattern: Fast & Slow pointers

• https://leetcode.com/problems/linked-list-cycle/
• https://leetcode.com/problems/linked-list-cycle-ii/
• https://leetcode.com/problems/happy-number/
• https://leetcode.com/problems/middle-of-the-linked-list/
• https://leetcode.com/problems/palindrome-linked-list/
• https://leetcode.com/problems/reorder-list/
• https://leetcode.com/problems/circular-array-loop/

Pattern: Merge Intervals

• https://leetcode.com/problems/merge-intervals/
• https://leetcode.com/problems/insert-interval/
• https://leetcode.com/problems/interval-list-intersections/
• https://leetcode.com/problems/meeting-rooms-ii/
• Could not find equivalent. Given a list of intervals with values, find the peak sum (i.e. if intervals are overlapping, sum their values)
• https://leetcode.com/problems/employee-free-time/

Pattern: Cyclic Sort

• Couldn't find equivalent for the first question. The second question below encompasses the first one though. See https://leetcode.com/problems/missing-number/discuss/859510/C%2B%2B-O(N)-O(1)-using-Cyclic-Sort for how grokking the coding interview approached these problems. It uses the fact that we can sort the array in O(n) without comparison operators
• https://leetcode.com/problems/missing-number/
• https://leetcode.com/problems/find-all-numbers-disappeared-in-an-array/
• https://leetcode.com/problems/find-all-duplicates-in-an-array/
• combine https://leetcode.com/problems/find-the-duplicate-number/ and https://leetcode.com/problems/missing-number/
• https://leetcode.com/problems/first-missing-positive/
• https://leetcode.com/problems/kth-missing-positive-number/

Pattern: In-place Reversal of a LinkedList

• https://leetcode.com/problems/reverse-linked-list/
• https://leetcode.com/problems/reverse-linked-list-ii/
• https://leetcode.com/problems/reverse-nodes-in-k-group/
• Next question is the same, but alternate each subgroup
• https://leetcode.com/problems/rotate-list/

Pattern: Tree Breadth First Search

• https://leetcode.com/problems/binary-tree-level-order-traversal/
• https://leetcode.com/problems/binary-tree-level-order-traversal-ii/
• https://leetcode.com/problems/binary-tree-zigzag-level-order-traversal/
• https://leetcode.com/problems/minimum-depth-of-binary-tree/
• https://leetcode.com/problems/inorder-successor-in-bst/ # Close, not exact
• https://leetcode.com/problems/populating-next-right-pointers-in-each-node/ # Close, grokk assumes non-perfect tree
• Next question is the same, but connect end nodes to the next level instead of null
• https://leetcode.com/problems/binary-tree-right-side-view/

Pattern: Tree Depth First Search

• https://leetcode.com/problems/path-sum/
• https://leetcode.com/problems/path-sum-ii/
• https://leetcode.com/problems/sum-root-to-leaf-numbers/
• https://leetcode.com/problems/check-if-a-string-is-a-valid-sequence-from-root-to-leaves-path-in-a-binary-tree/description/
• https://leetcode.com/problems/path-sum-iii/
• https://leetcode.com/problems/diameter-of-binary-tree/
• https://leetcode.com/problems/binary-tree-maximum-path-sum/

Pattern: Two Heaps

• https://leetcode.com/problems/find-median-from-data-stream/
• https://leetcode.com/problems/sliding-window-median/
• https://leetcode.com/problems/ipo/
• https://leetcode.com/problems/find-right-interval/

Pattern: Subsets

• https://leetcode.com/problems/subsets/
• https://leetcode.com/problems/subsets-ii/
• https://leetcode.com/problems/permutations/
• https://leetcode.com/problems/letter-case-permutation/
• https://leetcode.com/problems/generate-parentheses/
• https://leetcode.com/problems/generalized-abbreviation/
• https://leetcode.com/problems/different-ways-to-add-parentheses/
• https://leetcode.com/problems/unique-binary-search-trees-ii/
• https://leetcode.com/problems/unique-binary-search-trees/

Pattern: Modified Binary Search

• https://leetcode.com/problems/binary-search/ # Close enough. The grokking problem allows sorted input arrays as ascending or descending, which only introduces a simple check
• Did not find. Problem is find index of smallest element greater or equal to input value
• https://leetcode.com/problems/find-smallest-letter-greater-than-target/
• https://leetcode.com/problems/find-first-and-last-position-of-element-in-sorted-array/
• https://leetcode.com/problems/search-in-a-sorted-array-of-unknown-size/
• https://leetcode.com/problems/find-k-closest-elements/ (with K == 1)
• https://leetcode.com/problems/peak-index-in-a-mountain-array/
• https://leetcode.com/problems/find-in-mountain-array/
• https://leetcode.com/problems/search-in-rotated-sorted-array/
• Similar to previous, but find the number of rotations of the array.

Pattern: Bitwise XOR

• https://leetcode.com/problems/single-number/
• https://leetcode.com/problems/single-number-iii/
• https://leetcode.com/problems/complement-of-base-10-integer/
• https://leetcode.com/problems/flipping-an-image/

Pattern: Top 'K' elements

• Same as second question, but the first Grokking question wants the top K instead of the bottom K
• https://leetcode.com/problems/kth-largest-element-in-an-array
• https://leetcode.com/problems/k-closest-points-to-origin/
• https://leetcode.com/problems/minimum-cost-to-connect-sticks/
• https://leetcode.com/problems/top-k-frequent-elements/
• https://leetcode.com/problems/sort-characters-by-frequency/
• https://leetcode.com/problems/kth-largest-element-in-a-stream/
• https://leetcode.com/problems/find-k-closest-elements/
• https://leetcode.com/problems/least-number-of-unique-integers-after-k-removals/ closest leetcode or https://www.geeksforgeeks.org/maximum-distinct-elements-removing-k-elements/ for exact
• https://www.geeksforgeeks.org/sum-elements-k1th-k2th-smallest-elements/ no leetcode equivalent found
• https://leetcode.com/problems/reorganize-string/
• https://leetcode.com/problems/rearrange-string-k-distance-apart/
• https://leetcode.com/problems/task-scheduler/
• https://leetcode.com/problems/maximum-frequency-stack/

Pattern: K-way merge

• https://leetcode.com/problems/merge-k-sorted-lists/
• Same as previous, but return the Kth smallest number
• https://leetcode.com/problems/kth-smallest-element-in-a-sorted-matrix/
• https://leetcode.com/problems/smallest-range-covering-elements-from-k-lists/
• https://leetcode.com/problems/find-k-pairs-with-smallest-sums/ small difference, grokking has different sort order and wants the largest

Pattern: 0/1 Knapsack

• https://www.educative.io/courses/grokking-dynamic-programming-patterns-for-coding-interviews/RM1BDv71V60
• https://www.educative.io/courses/grokking-dynamic-programming-patterns-for-coding-interviews/3jEPRo5PDvx or https://leetcode.com/problems/partition-equal-subset-sum/
• https://www.educative.io/courses/grokking-dynamic-programming-patterns-for-coding-interviews/3j64vRY6JnR
• https://leetcode.com/problems/last-stone-weight-ii/ similar concept, but problem description is more abstract.
• https://leetcode.com/problems/combination-sum-ii/ similar, but return the number of combinations instead of the combinations
• https://leetcode.com/problems/target-sum/
• BONUS : Not in grokking, but I still found this very useful https://leetcode.com/problems/ones-and-zeroes/

Pattern: Topological Sort

• First problem is identical to the following three
• https://leetcode.com/problems/course-schedule/
• https://leetcode.com/problems/course-schedule-ii/
• Same as above, but return all instead of any
• https://leetcode.com/problems/alien-dictionary/
• https://leetcode.com/problems/sequence-reconstruction/description/
• https://leetcode.com/problems/minimum-height-trees/

Misc

• https://leetcode.com/problems/kth-largest-element-in-an-array/

Backtracking

• Combination Sum -> https://leetcode.com/problems/combination-sum/
• Word Search -> https://leetcode.com/problems/word-search/
• Sudoku Solver -> https://leetcode.com/problems/sudoku-solver/
• Factor Combinations -> LC Premium, matches title https://leetcode.com/problems/factor-combinations/
• Split A String Into The Max Number of Unique Substrings -> https://leetcode.com/problems/split-a-string-into-the-max-number-of-unique-substrings/

Multithreading

https://leetcode.com/problems/same-tree/
https://leetcode.com/problems/invert-binary-tree/
https://leetcode.com/problems/binary-search-tree-iterator/

Test your knowledge section:

• Valid Perfect Square -> https://leetcode.com/problems/valid-perfect-square/
• Best Time to Buy and Sell Stock -> https://leetcode.com/problems/best-time-to-buy-and-sell-stock/
• Daily Temperatures -> https://leetcode.com/problems/daily-temperatures/
• Group Anagrams -> https://leetcode.com/problems/group-anagrams/
• Decode String -> https://leetcode.com/problems/decode-string/
• Valid Sudoku -> https://leetcode.com/problems/valid-sudoku/
• Longest Valid Parentheses -> https://leetcode.com/problems/longest-valid-parentheses/

Monotonic Stack

• Next Greater Element -> https://leetcode.com/problems/next-greater-element-i/
• Daily Temperatures -> https://leetcode.com/problems/daily-temperatures/
• Remove Nodes From Linked List -> https://leetcode.com/problems/remove-nodes-from-linked-list/
• Remove All Adjacent Duplicates in String -> https://leetcode.com/problems/remove-all-adjacent-duplicates-in-string/
• Remove All Adjacent Duplicates in String II -> https://leetcode.com/problems/remove-all-adjacent-duplicates-in-string-ii/
• Remove K Digits -> https://leetcode.com/problems/remove-k-digits/

Thanks to everyone.

You're the goat!

Hi, Is it legal to share this course notes on GitHub?

@i-zanis topological orderings are not unique right?

yes .. they may vary

can someone share the updated list ?

I built this GPT for personalized mock interviews. Any programming language. With detailed feedback. Needs ChatGPT Plus for now: https://chat.openai.com/g/g-ngDadz7qM-mock-interviewer

Union Find:
https://leetcode.com/problems/redundant-connection/description/
https://leetcode.com/problems/number-of-provinces/description/
https://leetcode.com/problems/is-graph-bipartite/description/
https://leetcode.com/problems/path-with-minimum-effort/description/

Ordered Set:
https://leetcode.com/problems/merge-similar-items/description/
https://leetcode.com/problems/132-pattern/
https://leetcode.com/problems/my-calendar-i/
https://leetcode.com/problems/longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit/description/

Trie:

• https://leetcode.com/problems/implement-trie-prefix-tree/description/
• https://leetcode.com/problems/index-pairs-of-a-string/description/
• https://leetcode.com/problems/design-add-and-search-words-data-structure/
• https://leetcode.com/problems/extra-characters-in-a-string/description/
• https://leetcode.com/problems/search-suggestions-system/

Greedy Algorithms:

• https://leetcode.com/problems/valid-palindrome-ii/description/
• https://leetcode.com/problems/maximum-length-of-pair-chain/description/
• https://leetcode.com/problems/minimum-add-to-make-parentheses-valid/description/
• https://leetcode.com/problems/remove-duplicate-letters/description/
• https://leetcode.com/problems/largest-palindromic-number/description/
• https://leetcode.com/problems/removing-minimum-and-maximum-from-array/description/

Hashing:

• First Unique Character in a String : https://leetcode.com/problems/first-unique-character-in-a-string/description/
• Largest Unique Number : https://leetcode.com/problems/largest-unique-number/description/
• Maximum Number of Balloons: https://leetcode.com/problems/maximum-number-of-balloons/description/
• Longest Palindrome : https://leetcode.com/problems/longest-palindrome/description/
• Ransom Note : https://leetcode.com/problems/ransom-note/description/

https://leetstream.github.io/
It offers daily LeetCode problems categorized under 26 patterns, shuffled to ensure spaced repetition across different coding patterns.

is this list being maintained? can somebody please share the updated version if any?