DSArena

A repository dedicated to mastering my Data Structures and Algorithms skills.

LeetCode Topics

String

0003-longest-substring-without-repeating-characters
0005-longest-palindromic-substring
0006-zigzag-conversion
0008-string-to-integer-atoi
0013-roman-to-integer
0014-longest-common-prefix
0020-valid-parentheses
0028-find-the-index-of-the-first-occurrence-in-a-string
0043-multiply-strings
0049-group-anagrams
0058-length-of-last-word
0131-palindrome-partitioning
0151-reverse-words-in-a-string
0179-largest-number
0205-isomorphic-strings
0242-valid-anagram
0257-binary-tree-paths
0344-reverse-string
0345-reverse-vowels-of-a-string
0383-ransom-note
0387-first-unique-character-in-a-string
0389-find-the-difference
0392-is-subsequence
0412-fizz-buzz
0415-add-strings
0424-longest-repeating-character-replacement
0451-sort-characters-by-frequency
0782-jewels-and-stones
0812-rotate-string
0961-long-pressed-name
1006-vowel-spellchecker
1078-remove-outermost-parentheses
1264-maximum-number-of-words-you-can-type
1302-delete-characters-to-make-fancy-string
1353-find-resultant-array-after-removing-anagrams
1890-sum-of-beauty-of-all-substrings
2032-largest-odd-number-in-string
2137-final-value-of-variable-after-performing-operations
2346-largest-3-same-digit-number-in-string
2427-first-letter-to-appear-twice
2429-design-a-food-rating-system
2886-faulty-keyboard
2887-sort-vowels-in-a-string
3143-longest-unequal-adjacent-groups-subsequence-i
3396-valid-word
3462-vowels-game-in-a-string
3797-design-spreadsheet
3811-reverse-degree-of-a-string
3872-find-most-frequent-vowel-and-consonant

Array

0001-two-sum
0004-median-of-two-sorted-arrays
0011-container-with-most-water
0014-longest-common-prefix
0015-3sum
0026-remove-duplicates-from-sorted-array
0027-remove-element
0033-search-in-rotated-sorted-array
0034-find-first-and-last-position-of-element-in-sorted-array
0035-search-insert-position
0037-sudoku-solver
0039-combination-sum
0040-combination-sum-ii
0042-trapping-rain-water
0046-permutations
0048-rotate-image
0049-group-anagrams
0051-n-queens
0053-maximum-subarray
0054-spiral-matrix
0057-insert-interval
0064-minimum-path-sum
0074-search-a-2d-matrix
0075-sort-colors
0078-subsets
0081-search-in-rotated-sorted-array-ii
0088-merge-sorted-array
0090-subsets-ii
0118-pascals-triangle
0122-best-time-to-buy-and-sell-stock-ii
0128-longest-consecutive-sequence
0135-candy
0136-single-number
0137-single-number-ii
0150-evaluate-reverse-polish-notation
0153-find-minimum-in-rotated-sorted-array
0162-find-peak-element
0169-majority-element
0179-largest-number
0209-minimum-size-subarray-sum
0217-contains-duplicate
0219-contains-duplicate-ii
0238-product-of-array-except-self
0268-missing-number
0274-h-index
0275-h-index-ii
0287-find-the-duplicate-number
0347-top-k-frequent-elements
0349-intersection-of-two-arrays
0350-intersection-of-two-arrays-ii
0410-split-array-largest-sum
0448-find-all-numbers-disappeared-in-an-array
0485-max-consecutive-ones
0540-single-element-in-a-sorted-array
0560-subarray-sum-equals-k
0658-find-k-closest-elements
0682-baseball-game
0739-daily-temperatures
0792-binary-search
0875-longest-mountain-in-array
0882-peak-index-in-a-mountain-array
0907-koko-eating-bananas
0978-valid-mountain-array
1006-vowel-spellchecker
1127-last-stone-weight
1168-duplicate-zeros
1293-three-consecutive-odds
1305-number-of-visible-people-in-a-queue
1306-minimum-absolute-difference
1353-find-resultant-array-after-removing-anagrams
1395-minimum-time-visiting-all-points
1426-find-n-unique-integers-sum-up-to-zero
1482-how-many-numbers-are-smaller-than-the-current-number
1510-find-lucky-integer-in-an-array
1574-maximum-product-of-two-elements-in-an-array
1646-kth-missing-positive-number
1966-frequency-of-the-most-frequent-element
2023-design-movie-rental-system
2116-count-number-of-pairs-with-absolute-difference-k
2137-final-value-of-variable-after-performing-operations
2271-rearrange-array-elements-by-sign
2307-replace-non-coprime-numbers-in-array
2429-design-a-food-rating-system
2722-prime-in-diagonal
3143-longest-unequal-adjacent-groups-subsequence-i
3490-find-the-maximum-length-of-valid-subsequence-i
3612-adjacent-increasing-subarrays-detection-i
3619-adjacent-increasing-subarrays-detection-ii
3797-design-spreadsheet
3827-implement-router

Binary Search

0004-median-of-two-sorted-arrays
0033-search-in-rotated-sorted-array
0034-find-first-and-last-position-of-element-in-sorted-array
0035-search-insert-position
0069-sqrtx
0074-search-a-2d-matrix
0081-search-in-rotated-sorted-array-ii
0153-find-minimum-in-rotated-sorted-array
0162-find-peak-element
0209-minimum-size-subarray-sum
0268-missing-number
0275-h-index-ii
0287-find-the-duplicate-number
0349-intersection-of-two-arrays
0350-intersection-of-two-arrays-ii
0367-valid-perfect-square
0410-split-array-largest-sum
0540-single-element-in-a-sorted-array
0633-sum-of-square-numbers
0658-find-k-closest-elements
0792-binary-search
0882-peak-index-in-a-mountain-array
0907-koko-eating-bananas
1646-kth-missing-positive-number
1966-frequency-of-the-most-frequent-element
3619-adjacent-increasing-subarrays-detection-ii
3827-implement-router

Linked List

0002-add-two-numbers
0019-remove-nth-node-from-end-of-list
0021-merge-two-sorted-lists
0025-reverse-nodes-in-k-group
0141-linked-list-cycle
0142-linked-list-cycle-ii
0160-intersection-of-two-linked-lists
0203-remove-linked-list-elements
0206-reverse-linked-list
0234-palindrome-linked-list
0237-delete-node-in-a-linked-list
0908-middle-of-the-linked-list
1411-convert-binary-number-in-a-linked-list-to-integer

Math

0002-add-two-numbers
0013-roman-to-integer
0029-divide-two-integers
0043-multiply-strings
0048-rotate-image
0069-sqrtx
0070-climbing-stairs
0150-evaluate-reverse-polish-notation
0172-factorial-trailing-zeroes
0231-power-of-two
0264-ugly-number-ii
0268-missing-number
0326-power-of-three
0342-power-of-four
0367-valid-perfect-square
0412-fizz-buzz
0415-add-strings
0633-sum-of-square-numbers
0867-new-21-game
1395-minimum-time-visiting-all-points
1411-convert-binary-number-in-a-linked-list-to-integer
1426-find-n-unique-integers-sum-up-to-zero
1440-convert-integer-to-the-sum-of-two-no-zero-integers
1448-maximum-69-number
1585-the-kth-factor-of-n
1817-calculate-money-in-leetcode-bank
2032-largest-odd-number-in-string
2050-count-good-numbers
2288-count-operations-to-obtain-zero
2307-replace-non-coprime-numbers-in-array
2722-prime-in-diagonal
3462-vowels-game-in-a-string
3676-smallest-number-with-all-set-bits
3830-find-closest-person

Bit Manipulation

0029-divide-two-integers
0078-subsets
0090-subsets-ii
0136-single-number
0137-single-number-ii
0191-number-of-1-bits
0231-power-of-two
0268-missing-number
0287-find-the-duplicate-number
0342-power-of-four
0389-find-the-difference
2427-first-letter-to-appear-twice
3676-smallest-number-with-all-set-bits

Recursion

0002-add-two-numbers
0021-merge-two-sorted-lists
0025-reverse-nodes-in-k-group
0203-remove-linked-list-elements
0206-reverse-linked-list
0231-power-of-two
0234-palindrome-linked-list
0326-power-of-three
0342-power-of-four
2050-count-good-numbers

Stack

0020-valid-parentheses
0042-trapping-rain-water
0094-binary-tree-inorder-traversal
0144-binary-tree-preorder-traversal
0145-binary-tree-postorder-traversal
0150-evaluate-reverse-polish-notation
0155-min-stack
0225-implement-stack-using-queues
0232-implement-queue-using-stacks
0234-palindrome-linked-list
0682-baseball-game
0739-daily-temperatures
1078-remove-outermost-parentheses
1305-number-of-visible-people-in-a-queue
2307-replace-non-coprime-numbers-in-array

Design

0155-min-stack
0225-implement-stack-using-queues
0232-implement-queue-using-stacks
2023-design-movie-rental-system
2429-design-a-food-rating-system
3678-design-task-manager
3797-design-spreadsheet
3827-implement-router

Queue

0225-implement-stack-using-queues
0232-implement-queue-using-stacks
0387-first-unique-character-in-a-string
3827-implement-router

Hash Table

0001-two-sum
0003-longest-substring-without-repeating-characters
0013-roman-to-integer
0037-sudoku-solver
0049-group-anagrams
0128-longest-consecutive-sequence
0141-linked-list-cycle
0142-linked-list-cycle-ii
0160-intersection-of-two-linked-lists
0169-majority-element
0205-isomorphic-strings
0217-contains-duplicate
0219-contains-duplicate-ii
0242-valid-anagram
0264-ugly-number-ii
0268-missing-number
0347-top-k-frequent-elements
0349-intersection-of-two-arrays
0350-intersection-of-two-arrays-ii
0383-ransom-note
0387-first-unique-character-in-a-string
0389-find-the-difference
0424-longest-repeating-character-replacement
0448-find-all-numbers-disappeared-in-an-array
0451-sort-characters-by-frequency
0560-subarray-sum-equals-k
0782-jewels-and-stones
1006-vowel-spellchecker
1264-maximum-number-of-words-you-can-type
1353-find-resultant-array-after-removing-anagrams
1482-how-many-numbers-are-smaller-than-the-current-number
1510-find-lucky-integer-in-an-array
1890-sum-of-beauty-of-all-substrings
2023-design-movie-rental-system
2116-count-number-of-pairs-with-absolute-difference-k
2427-first-letter-to-appear-twice
2429-design-a-food-rating-system
3678-design-task-manager
3797-design-spreadsheet
3827-implement-router
3872-find-most-frequent-vowel-and-consonant

Sliding Window

0003-longest-substring-without-repeating-characters
0209-minimum-size-subarray-sum
0219-contains-duplicate-ii
0424-longest-repeating-character-replacement
0658-find-k-closest-elements
0867-new-21-game
1966-frequency-of-the-most-frequent-element

Backtracking

0037-sudoku-solver
0039-combination-sum
0040-combination-sum-ii
0046-permutations
0051-n-queens
0052-n-queens-ii
0078-subsets
0090-subsets-ii
0131-palindrome-partitioning
0257-binary-tree-paths

Tree

0094-binary-tree-inorder-traversal
0100-same-tree
0102-binary-tree-level-order-traversal
0103-binary-tree-zigzag-level-order-traversal
0104-maximum-depth-of-binary-tree
0110-balanced-binary-tree
0111-minimum-depth-of-binary-tree
0112-path-sum
0144-binary-tree-preorder-traversal
0145-binary-tree-postorder-traversal
0257-binary-tree-paths
0543-diameter-of-binary-tree
0975-range-sum-of-bst
2384-root-equals-sum-of-children

Binary Tree

0094-binary-tree-inorder-traversal
0100-same-tree
0102-binary-tree-level-order-traversal
0103-binary-tree-zigzag-level-order-traversal
0104-maximum-depth-of-binary-tree
0110-balanced-binary-tree
0111-minimum-depth-of-binary-tree
0112-path-sum
0144-binary-tree-preorder-traversal
0145-binary-tree-postorder-traversal
0257-binary-tree-paths
0543-diameter-of-binary-tree
0975-range-sum-of-bst
2384-root-equals-sum-of-children

Depth-First Search

0094-binary-tree-inorder-traversal
0100-same-tree
0104-maximum-depth-of-binary-tree
0110-balanced-binary-tree
0111-minimum-depth-of-binary-tree
0112-path-sum
0144-binary-tree-preorder-traversal
0145-binary-tree-postorder-traversal
0257-binary-tree-paths
0543-diameter-of-binary-tree
0975-range-sum-of-bst

Breadth-First Search

0100-same-tree
0102-binary-tree-level-order-traversal
0103-binary-tree-zigzag-level-order-traversal
0104-maximum-depth-of-binary-tree
0111-minimum-depth-of-binary-tree
0112-path-sum

Dynamic Programming

0005-longest-palindromic-substring
0042-trapping-rain-water
0053-maximum-subarray
0064-minimum-path-sum
0070-climbing-stairs
0118-pascals-triangle
0122-best-time-to-buy-and-sell-stock-ii
0131-palindrome-partitioning
0264-ugly-number-ii
0392-is-subsequence
0410-split-array-largest-sum
0867-new-21-game
0875-longest-mountain-in-array
3143-longest-unequal-adjacent-groups-subsequence-i
3490-find-the-maximum-length-of-valid-subsequence-i

Sorting

0015-3sum
0049-group-anagrams
0075-sort-colors
0088-merge-sorted-array
0169-majority-element
0179-largest-number
0217-contains-duplicate
0242-valid-anagram
0268-missing-number
0274-h-index
0347-top-k-frequent-elements
0349-intersection-of-two-arrays
0350-intersection-of-two-arrays-ii
0389-find-the-difference
0451-sort-characters-by-frequency
0658-find-k-closest-elements
1306-minimum-absolute-difference
1353-find-resultant-array-after-removing-anagrams
1482-how-many-numbers-are-smaller-than-the-current-number
1574-maximum-product-of-two-elements-in-an-array
1966-frequency-of-the-most-frequent-element
2887-sort-vowels-in-a-string

Two Pointers

0005-longest-palindromic-substring
0011-container-with-most-water
0015-3sum
0019-remove-nth-node-from-end-of-list
0026-remove-duplicates-from-sorted-array
0027-remove-element
0028-find-the-index-of-the-first-occurrence-in-a-string
0042-trapping-rain-water
0075-sort-colors
0088-merge-sorted-array
0141-linked-list-cycle
0142-linked-list-cycle-ii
0151-reverse-words-in-a-string
0160-intersection-of-two-linked-lists
0234-palindrome-linked-list
0287-find-the-duplicate-number
0344-reverse-string
0345-reverse-vowels-of-a-string
0349-intersection-of-two-arrays
0350-intersection-of-two-arrays-ii
0392-is-subsequence
0633-sum-of-square-numbers
0658-find-k-closest-elements
0875-longest-mountain-in-array
0908-middle-of-the-linked-list
0961-long-pressed-name
1168-duplicate-zeros
2271-rearrange-array-elements-by-sign

Greedy

0011-container-with-most-water
0122-best-time-to-buy-and-sell-stock-ii
0135-candy
0179-largest-number
0410-split-array-largest-sum
1448-maximum-69-number
1966-frequency-of-the-most-frequent-element
2032-largest-odd-number-in-string
3143-longest-unequal-adjacent-groups-subsequence-i

Divide and Conquer

0004-median-of-two-sorted-arrays
0053-maximum-subarray
0169-majority-element
0191-number-of-1-bits
0347-top-k-frequent-elements

Monotonic Stack

0042-trapping-rain-water
0739-daily-temperatures
1305-number-of-visible-people-in-a-queue

Heap (Priority Queue)

0264-ugly-number-ii
0347-top-k-frequent-elements
0451-sort-characters-by-frequency
0658-find-k-closest-elements
1127-last-stone-weight
1574-maximum-product-of-two-elements-in-an-array
2023-design-movie-rental-system
2429-design-a-food-rating-system
3678-design-task-manager

Bucket Sort

0347-top-k-frequent-elements
0451-sort-characters-by-frequency

Counting

0169-majority-element
0347-top-k-frequent-elements
0383-ransom-note
0387-first-unique-character-in-a-string
0451-sort-characters-by-frequency
1510-find-lucky-integer-in-an-array
1890-sum-of-beauty-of-all-substrings
2116-count-number-of-pairs-with-absolute-difference-k
2427-first-letter-to-appear-twice
3872-find-most-frequent-vowel-and-consonant

Quickselect

0347-top-k-frequent-elements

Prefix Sum

0209-minimum-size-subarray-sum
0238-product-of-array-except-self
0410-split-array-largest-sum
0560-subarray-sum-equals-k
1966-frequency-of-the-most-frequent-element

Trie

0014-longest-common-prefix

Simulation

0043-multiply-strings
0054-spiral-matrix
0412-fizz-buzz
0415-add-strings
0682-baseball-game
2137-final-value-of-variable-after-performing-operations
2271-rearrange-array-elements-by-sign
2288-count-operations-to-obtain-zero
2886-faulty-keyboard
3811-reverse-degree-of-a-string

Matrix

0037-sudoku-solver
0048-rotate-image
0054-spiral-matrix
0064-minimum-path-sum
0074-search-a-2d-matrix
2722-prime-in-diagonal
3797-design-spreadsheet

String Matching

0028-find-the-index-of-the-first-occurrence-in-a-string
0812-rotate-string

Binary Search Tree

0975-range-sum-of-bst

Union Find

0128-longest-consecutive-sequence

Number Theory

1585-the-kth-factor-of-n
2307-replace-non-coprime-numbers-in-array
2722-prime-in-diagonal

Probability and Statistics

0867-new-21-game

Counting Sort

0274-h-index
1482-how-many-numbers-are-smaller-than-the-current-number

Geometry

1395-minimum-time-visiting-all-points

Enumeration

0875-longest-mountain-in-array

Brainteaser

3462-vowels-game-in-a-string

Game Theory

3462-vowels-game-in-a-string

Database

1462-list-the-products-ordered-in-a-period
1664-find-users-with-valid-e-mails

Ordered Set

2023-design-movie-rental-system
2429-design-a-food-rating-system
3678-design-task-manager
3827-implement-router

Memoization

0070-climbing-stairs