Leetcode

Collection of LeetCode questions to ace the coding interview! - Created using LeetHub

LeetCode Topics

Array

0001-two-sum
0004-median-of-two-sorted-arrays
0011-container-with-most-water
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
0036-valid-sudoku
0037-sudoku-solver
0039-combination-sum
0041-first-missing-positive
0042-trapping-rain-water
0046-permutations
0049-group-anagrams
0053-maximum-subarray
0054-spiral-matrix
0056-merge-intervals
0066-plus-one
0073-set-matrix-zeroes
0074-search-a-2d-matrix
0075-sort-colors
0078-subsets
0080-remove-duplicates-from-sorted-array-ii
0081-search-in-rotated-sorted-array-ii
0088-merge-sorted-array
0090-subsets-ii
0118-pascals-triangle
0121-best-time-to-buy-and-sell-stock
0128-longest-consecutive-sequence
0150-evaluate-reverse-polish-notation
0152-maximum-product-subarray
0153-find-minimum-in-rotated-sorted-array
0162-find-peak-element
0167-two-sum-ii-input-array-is-sorted
0169-majority-element
0189-rotate-array
0209-minimum-size-subarray-sum
0215-kth-largest-element-in-an-array
0217-contains-duplicate
0219-contains-duplicate-ii
0238-product-of-array-except-self
0283-move-zeroes
0287-find-the-duplicate-number
0303-range-sum-query-immutable
0334-increasing-triplet-subsequence
0347-top-k-frequent-elements
0373-find-k-pairs-with-smallest-sums
0416-partition-equal-subset-sum
0436-find-right-interval
0485-max-consecutive-ones
0486-predict-the-winner
0494-target-sum
0496-next-greater-element-i
0560-subarray-sum-equals-k
0605-can-place-flowers
0628-maximum-product-of-three-numbers
0643-maximum-average-subarray-i
0724-find-pivot-index
0735-asteroid-collision
0739-daily-temperatures
0745-find-smallest-letter-greater-than-target
0792-binary-search
0877-stone-game
0883-car-fleet
0940-fruit-into-baskets
0948-sort-an-array
0966-binary-subarrays-with-sum
1046-max-consecutive-ones-iii
1319-unique-number-of-occurrences
1370-count-number-of-nice-subarrays
1464-maximum-product-of-two-elements-in-an-array
1476-count-negative-numbers-in-a-sorted-matrix
1478-maximum-number-of-events-that-can-be-attended
1514-minimum-value-to-get-positive-step-by-step-sum
1528-kids-with-the-greatest-number-of-candies
1586-longest-subarray-of-1s-after-deleting-one-element
1603-running-sum-of-1d-array
1693-sum-of-all-odd-length-subarrays
1741-sort-array-by-increasing-frequency
1798-max-number-of-k-sum-pairs
1833-find-the-highest-altitude
1872-stone-game-viii
1878-check-if-array-is-sorted-and-rotated
1946-minimum-absolute-sum-difference
1966-frequency-of-the-most-frequent-element
1983-maximum-population-year
2005-check-if-all-the-integers-in-a-range-are-covered
2091-removing-minimum-and-maximum-from-array
2116-count-number-of-pairs-with-absolute-difference-k
2144-maximum-difference-between-increasing-elements
2210-find-target-indices-after-sorting-array
2271-rearrange-array-elements-by-sign
2316-count-hills-and-valleys-in-an-array
2497-maximum-matching-of-players-with-trainers
2552-maximum-sum-of-distinct-subarrays-with-length-k
2766-find-the-prefix-common-array-of-two-arrays
2792-neighboring-bitwise-xor
2958-length-of-longest-subarray-with-at-most-k-frequency
3718-smallest-missing-multiple-of-k
3731-find-missing-elements
3875-construct-uniform-parity-array-i
3876-construct-uniform-parity-array-ii
3904-smallest-stable-index-ii

Dynamic Programming

0022-generate-parentheses
0032-longest-valid-parentheses
0042-trapping-rain-water
0053-maximum-subarray
0062-unique-paths
0118-pascals-triangle
0121-best-time-to-buy-and-sell-stock
0152-maximum-product-subarray
0338-counting-bits
0392-is-subsequence
0416-partition-equal-subset-sum
0486-predict-the-winner
0494-target-sum
0647-palindromic-substrings
0877-stone-game
1013-fibonacci-number
1586-longest-subarray-of-1s-after-deleting-one-element
1872-stone-game-viii

String

0003-longest-substring-without-repeating-characters
0006-zigzag-conversion
0008-string-to-integer-atoi
0014-longest-common-prefix
0020-valid-parentheses
0022-generate-parentheses
0028-find-the-index-of-the-first-occurrence-in-a-string
0032-longest-valid-parentheses
0038-count-and-say
0049-group-anagrams
0067-add-binary
0076-minimum-window-substring
0093-restore-ip-addresses
0125-valid-palindrome
0151-reverse-words-in-a-string
0168-excel-sheet-column-title
0214-shortest-palindrome
0242-valid-anagram
0316-remove-duplicate-letters
0344-reverse-string
0345-reverse-vowels-of-a-string
0387-first-unique-character-in-a-string
0392-is-subsequence
0394-decode-string
0409-longest-palindrome
0412-fizz-buzz
0415-add-strings
0424-longest-repeating-character-replacement
0443-string-compression
0567-permutation-in-string
0647-palindromic-substrings
0680-valid-palindrome-ii
0686-repeated-string-match
1146-greatest-common-divisor-of-strings
1508-longest-happy-prefix
1537-maximum-score-after-splitting-a-string
1567-maximum-number-of-vowels-in-a-substring-of-given-length
1647-minimum-deletions-to-make-character-frequencies-unique
1648-minimum-insertions-to-balance-a-parentheses-string
1894-merge-strings-alternately
2221-check-if-a-parentheses-string-can-be-valid
2470-removing-stars-from-a-string
2904-shortest-and-lexicographically-smallest-beautiful-string
3014-minimum-number-of-pushes-to-type-word-i
3016-minimum-number-of-pushes-to-type-word-ii
3090-maximum-length-substring-with-two-occurrences
3455-minimum-length-of-string-after-operations
3617-find-the-original-typed-string-i

Backtracking

0022-generate-parentheses
0037-sudoku-solver
0039-combination-sum
0046-permutations
0078-subsets
0090-subsets-ii
0093-restore-ip-addresses
0494-target-sum

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
0167-two-sum-ii-input-array-is-sorted
0209-minimum-size-subarray-sum
0287-find-the-duplicate-number
0436-find-right-interval
0745-find-smallest-letter-greater-than-target
0792-binary-search
1046-max-consecutive-ones-iii
1476-count-negative-numbers-in-a-sorted-matrix
1946-minimum-absolute-sum-difference
1966-frequency-of-the-most-frequent-element
2210-find-target-indices-after-sorting-array

Sorting

0015-3sum
0049-group-anagrams
0056-merge-intervals
0075-sort-colors
0088-merge-sorted-array
0148-sort-list
0169-majority-element
0215-kth-largest-element-in-an-array
0217-contains-duplicate
0242-valid-anagram
0347-top-k-frequent-elements
0436-find-right-interval
0628-maximum-product-of-three-numbers
0883-car-fleet
0948-sort-an-array
1464-maximum-product-of-two-elements-in-an-array
1478-maximum-number-of-events-that-can-be-attended
1647-minimum-deletions-to-make-character-frequencies-unique
1741-sort-array-by-increasing-frequency
1798-max-number-of-k-sum-pairs
1946-minimum-absolute-sum-difference
1966-frequency-of-the-most-frequent-element
2210-find-target-indices-after-sorting-array
2497-maximum-matching-of-players-with-trainers
3016-minimum-number-of-pushes-to-type-word-ii
3731-find-missing-elements

Ordered Set

1946-minimum-absolute-sum-difference

Hash Table

0001-two-sum
0003-longest-substring-without-repeating-characters
0036-valid-sudoku
0037-sudoku-solver
0041-first-missing-positive
0049-group-anagrams
0073-set-matrix-zeroes
0076-minimum-window-substring
0128-longest-consecutive-sequence
0141-linked-list-cycle
0142-linked-list-cycle-ii
0146-lru-cache
0160-intersection-of-two-linked-lists
0169-majority-element
0202-happy-number
0217-contains-duplicate
0219-contains-duplicate-ii
0242-valid-anagram
0347-top-k-frequent-elements
0387-first-unique-character-in-a-string
0409-longest-palindrome
0424-longest-repeating-character-replacement
0496-next-greater-element-i
0560-subarray-sum-equals-k
0567-permutation-in-string
0940-fruit-into-baskets
0966-binary-subarrays-with-sum
1319-unique-number-of-occurrences
1370-count-number-of-nice-subarrays
1647-minimum-deletions-to-make-character-frequencies-unique
1741-sort-array-by-increasing-frequency
1798-max-number-of-k-sum-pairs
2005-check-if-all-the-integers-in-a-range-are-covered
2116-count-number-of-pairs-with-absolute-difference-k
2552-maximum-sum-of-distinct-subarrays-with-length-k
2766-find-the-prefix-common-array-of-two-arrays
2958-length-of-longest-subarray-with-at-most-k-frequency
3016-minimum-number-of-pushes-to-type-word-ii
3090-maximum-length-substring-with-two-occurrences
3455-minimum-length-of-string-after-operations
3718-smallest-missing-multiple-of-k
3731-find-missing-elements

Counting

0169-majority-element
0347-top-k-frequent-elements
0387-first-unique-character-in-a-string
1983-maximum-population-year
2116-count-number-of-pairs-with-absolute-difference-k
3016-minimum-number-of-pushes-to-type-word-ii
3455-minimum-length-of-string-after-operations

Linked List

0002-add-two-numbers
0021-merge-two-sorted-lists
0024-swap-nodes-in-pairs
0083-remove-duplicates-from-sorted-list
0092-reverse-linked-list-ii
0141-linked-list-cycle
0142-linked-list-cycle-ii
0146-lru-cache
0148-sort-list
0160-intersection-of-two-linked-lists
0206-reverse-linked-list
0234-palindrome-linked-list
0237-delete-node-in-a-linked-list
0445-add-two-numbers-ii
1411-convert-binary-number-in-a-linked-list-to-integer
2058-find-the-minimum-and-maximum-number-of-nodes-between-critical-points

Math

0002-add-two-numbers
0007-reverse-integer
0009-palindrome-number
0062-unique-paths
0066-plus-one
0067-add-binary
0069-sqrtx
0150-evaluate-reverse-polish-notation
0168-excel-sheet-column-title
0189-rotate-array
0202-happy-number
0412-fizz-buzz
0415-add-strings
0445-add-two-numbers-ii
0486-predict-the-winner
0628-maximum-product-of-three-numbers
0877-stone-game
1013-fibonacci-number
1146-greatest-common-divisor-of-strings
1370-count-number-of-nice-subarrays
1411-convert-binary-number-in-a-linked-list-to-integer
1693-sum-of-all-odd-length-subarrays
1872-stone-game-viii
3014-minimum-number-of-pushes-to-type-word-i
3345-smallest-divisible-digit-product-i
3622-check-divisibility-by-digit-sum-and-product
3875-construct-uniform-parity-array-i
3876-construct-uniform-parity-array-ii

Stack

0020-valid-parentheses
0032-longest-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
0316-remove-duplicate-letters
0394-decode-string
0445-add-two-numbers-ii
0496-next-greater-element-i
0735-asteroid-collision
0739-daily-temperatures
0883-car-fleet
1648-minimum-insertions-to-balance-a-parentheses-string
2221-check-if-a-parentheses-string-can-be-valid
2470-removing-stars-from-a-string

Recursion

0002-add-two-numbers
0021-merge-two-sorted-lists
0024-swap-nodes-in-pairs
0206-reverse-linked-list
0234-palindrome-linked-list
0394-decode-string
0486-predict-the-winner
1013-fibonacci-number

Two Pointers

0011-container-with-most-water
0015-3sum
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
0080-remove-duplicates-from-sorted-array-ii
0088-merge-sorted-array
0125-valid-palindrome
0141-linked-list-cycle
0142-linked-list-cycle-ii
0148-sort-list
0151-reverse-words-in-a-string
0160-intersection-of-two-linked-lists
0167-two-sum-ii-input-array-is-sorted
0189-rotate-array
0202-happy-number
0234-palindrome-linked-list
0283-move-zeroes
0287-find-the-duplicate-number
0344-reverse-string
0345-reverse-vowels-of-a-string
0392-is-subsequence
0443-string-compression
0567-permutation-in-string
0647-palindromic-substrings
0680-valid-palindrome-ii
1798-max-number-of-k-sum-pairs
1894-merge-strings-alternately
2271-rearrange-array-elements-by-sign
2497-maximum-matching-of-players-with-trainers

Bit Manipulation

0067-add-binary
0078-subsets
0090-subsets-ii
0287-find-the-duplicate-number
0338-counting-bits
2766-find-the-prefix-common-array-of-two-arrays
2792-neighboring-bitwise-xor

Matrix

0036-valid-sudoku
0037-sudoku-solver
0054-spiral-matrix
0073-set-matrix-zeroes
0074-search-a-2d-matrix
1476-count-negative-numbers-in-a-sorted-matrix

Divide and Conquer

0004-median-of-two-sorted-arrays
0053-maximum-subarray
0148-sort-list
0169-majority-element
0215-kth-largest-element-in-an-array
0347-top-k-frequent-elements
0948-sort-an-array

Sliding Window

0003-longest-substring-without-repeating-characters
0076-minimum-window-substring
0209-minimum-size-subarray-sum
0219-contains-duplicate-ii
0424-longest-repeating-character-replacement
0567-permutation-in-string
0643-maximum-average-subarray-i
0940-fruit-into-baskets
0966-binary-subarrays-with-sum
1046-max-consecutive-ones-iii
1370-count-number-of-nice-subarrays
1567-maximum-number-of-vowels-in-a-substring-of-given-length
1586-longest-subarray-of-1s-after-deleting-one-element
1966-frequency-of-the-most-frequent-element
2552-maximum-sum-of-distinct-subarrays-with-length-k
2904-shortest-and-lexicographically-smallest-beautiful-string
2958-length-of-longest-subarray-with-at-most-k-frequency
3090-maximum-length-substring-with-two-occurrences

String Matching

0028-find-the-index-of-the-first-occurrence-in-a-string
0214-shortest-palindrome
0686-repeated-string-match
1508-longest-happy-prefix

Trie

0014-longest-common-prefix

Greedy

0011-container-with-most-water
0316-remove-duplicate-letters
0334-increasing-triplet-subsequence
0409-longest-palindrome
0605-can-place-flowers
0680-valid-palindrome-ii
1478-maximum-number-of-events-that-can-be-attended
1647-minimum-deletions-to-make-character-frequencies-unique
1648-minimum-insertions-to-balance-a-parentheses-string
1966-frequency-of-the-most-frequent-element
2091-removing-minimum-and-maximum-from-array
2221-check-if-a-parentheses-string-can-be-valid
2497-maximum-matching-of-players-with-trainers
3014-minimum-number-of-pushes-to-type-word-i
3016-minimum-number-of-pushes-to-type-word-ii

Simulation

0054-spiral-matrix
0067-add-binary
0412-fizz-buzz
0415-add-strings
0735-asteroid-collision
2271-rearrange-array-elements-by-sign
2470-removing-stars-from-a-string

Design

0146-lru-cache
0155-min-stack
0225-implement-stack-using-queues
0232-implement-queue-using-stacks
0303-range-sum-query-immutable

Prefix Sum

0209-minimum-size-subarray-sum
0238-product-of-array-except-self
0303-range-sum-query-immutable
0560-subarray-sum-equals-k
0724-find-pivot-index
0966-binary-subarrays-with-sum
1046-max-consecutive-ones-iii
1370-count-number-of-nice-subarrays
1514-minimum-value-to-get-positive-step-by-step-sum
1537-maximum-score-after-splitting-a-string
1603-running-sum-of-1d-array
1693-sum-of-all-odd-length-subarrays
1833-find-the-highest-altitude
1872-stone-game-viii
1966-frequency-of-the-most-frequent-element
1983-maximum-population-year
2005-check-if-all-the-integers-in-a-range-are-covered
3904-smallest-stable-index-ii

Monotonic Stack

0042-trapping-rain-water
0316-remove-duplicate-letters
0496-next-greater-element-i
0739-daily-temperatures
0883-car-fleet

Heap (Priority Queue)

0215-kth-largest-element-in-an-array
0347-top-k-frequent-elements
0373-find-k-pairs-with-smallest-sums
0948-sort-an-array
1464-maximum-product-of-two-elements-in-an-array
1478-maximum-number-of-events-that-can-be-attended

Quickselect

0215-kth-largest-element-in-an-array
0347-top-k-frequent-elements

Bucket Sort

0347-top-k-frequent-elements
0948-sort-an-array

Union Find

0128-longest-consecutive-sequence

Combinatorics

0062-unique-paths

Memoization

1013-fibonacci-number

Queue

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

Merge Sort

0148-sort-list
0948-sort-an-array

Radix Sort

0948-sort-an-array

Counting Sort

0948-sort-an-array

Rolling Hash

0214-shortest-palindrome
1508-longest-happy-prefix

Hash Function

0214-shortest-palindrome
1508-longest-happy-prefix

Database

0175-combine-two-tables
0176-second-highest-salary
0181-employees-earning-more-than-their-managers
0182-duplicate-emails
0183-customers-who-never-order
0196-delete-duplicate-emails
0570-managers-with-at-least-5-direct-reports
0584-find-customer-referee
0586-customer-placing-the-largest-number-of-orders
0595-big-countries
0596-classes-with-at-least-5-students
0620-not-boring-movies
1045-customers-who-bought-all-products
1141-user-activity-for-the-past-30-days-i
1153-product-sales-analysis-i
1158-market-analysis-i
1174-immediate-food-delivery-ii
1258-article-views-i
1393-capital-gainloss
1484-group-sold-products-by-the-date
1509-replace-employee-id-with-the-unique-identifier
1527-patients-with-a-condition
1581-customer-who-visited-but-did-not-make-any-transactions
1667-fix-names-in-a-table
1693-daily-leads-and-partners
1724-customer-who-visited-but-did-not-make-any-transactions
1729-find-followers-count
1757-recyclable-and-low-fat-products
1827-invalid-tweets
1873-calculate-special-bonus
1907-count-salary-categories
1908-recyclable-and-low-fat-products
2356-number-of-unique-subjects-taught-by-each-teacher

Doubly-Linked List

0146-lru-cache

Tree

0094-binary-tree-inorder-traversal
0110-balanced-binary-tree
0144-binary-tree-preorder-traversal
0145-binary-tree-postorder-traversal

Depth-First Search

0094-binary-tree-inorder-traversal
0110-balanced-binary-tree
0144-binary-tree-preorder-traversal
0145-binary-tree-postorder-traversal

Binary Tree

0094-binary-tree-inorder-traversal
0110-balanced-binary-tree
0144-binary-tree-preorder-traversal
0145-binary-tree-postorder-traversal

Game Theory

0486-predict-the-winner
0877-stone-game
1872-stone-game-viii

Enumeration

3345-smallest-divisible-digit-product-i

Minimax

1872-stone-game-viii

Zero-Sum Game

1872-stone-game-viii