LeetCode

Collection of LeetCode questions to ace the coding interview! Created using Leethub.

LeetCode Topics

Array

0001-two-sum
0011-container-with-most-water
0014-longest-common-prefix
0015-3sum
0016-3sum-closest
0018-4sum
0026-remove-duplicates-from-sorted-array
0033-search-in-rotated-sorted-array
0034-find-first-and-last-position-of-element-in-sorted-array
0036-valid-sudoku
0039-combination-sum
0040-combination-sum-ii
0042-trapping-rain-water
0045-jump-game-ii
0046-permutations
0048-rotate-image
0049-group-anagrams
0051-n-queens
0053-maximum-subarray
0054-spiral-matrix
0055-jump-game
0056-merge-intervals
0057-insert-interval
0073-set-matrix-zeroes
0074-search-a-2d-matrix
0075-sort-colors
0078-subsets
0079-word-search
0084-largest-rectangle-in-histogram
0088-merge-sorted-array
0090-subsets-ii
0105-construct-binary-tree-from-preorder-and-inorder-traversal
0121-best-time-to-buy-and-sell-stock
0122-best-time-to-buy-and-sell-stock-ii
0128-longest-consecutive-sequence
0130-surrounded-regions
0134-gas-station
0150-evaluate-reverse-polish-notation
0152-maximum-product-subarray
0153-find-minimum-in-rotated-sorted-array
0154-find-minimum-in-rotated-sorted-array-ii
0167-two-sum-ii-input-array-is-sorted
0169-majority-element
0200-number-of-islands
0209-minimum-size-subarray-sum
0212-word-search-ii
0215-kth-largest-element-in-an-array
0217-contains-duplicate
0238-product-of-array-except-self
0283-move-zeroes
0287-find-the-duplicate-number
0347-top-k-frequent-elements
0410-split-array-largest-sum
0417-pacific-atlantic-water-flow
0419-battleships-in-a-board
0435-non-overlapping-intervals
0452-minimum-number-of-arrows-to-burst-balloons
0463-island-perimeter
0496-next-greater-element-i
0503-next-greater-element-ii
0542-01-matrix
0594-longest-harmonious-subsequence
0605-can-place-flowers
0611-valid-triangle-number
0621-task-scheduler
0643-maximum-average-subarray-i
0695-max-area-of-island
0729-my-calendar-i
0733-flood-fill
0735-asteroid-collision
0739-daily-temperatures
0792-binary-search
0883-car-fleet
0907-koko-eating-bananas
0940-fruit-into-baskets
1014-k-closest-points-to-origin
1019-squares-of-a-sorted-array
1036-rotting-oranges
1046-max-consecutive-ones-iii
1056-capacity-to-ship-packages-within-d-days
1073-number-of-enclaves
1117-as-far-from-land-as-possible
1127-last-stone-weight
1171-shortest-path-in-binary-matrix
1408-find-the-smallest-divisor-given-a-threshold
1547-destination-city
1570-final-prices-with-a-special-discount-in-a-shop
1586-longest-subarray-of-1s-after-deleting-one-element
1605-minimum-number-of-days-to-make-m-bouquets
1675-magnetic-force-between-two-balls
1798-max-number-of-k-sum-pairs
1876-map-of-highest-peak
1950-sign-of-the-product-of-an-array
2035-count-sub-islands
2058-concatenation-of-array
2292-counting-words-with-a-given-prefix
2428-equal-row-and-column-pairs
2665-minimum-time-to-repair-cars
3309-count-prefix-and-suffix-pairs-i
3329-find-the-length-of-the-longest-common-prefix

Hash Table

0001-two-sum
0003-longest-substring-without-repeating-characters
0017-letter-combinations-of-a-phone-number
0036-valid-sudoku
0049-group-anagrams
0073-set-matrix-zeroes
0105-construct-binary-tree-from-preorder-and-inorder-traversal
0128-longest-consecutive-sequence
0133-clone-graph
0138-copy-list-with-random-pointer
0141-linked-list-cycle
0146-lru-cache
0169-majority-element
0208-implement-trie-prefix-tree
0217-contains-duplicate
0242-valid-anagram
0347-top-k-frequent-elements
0355-design-twitter
0383-ransom-note
0409-longest-palindrome
0424-longest-repeating-character-replacement
0438-find-all-anagrams-in-a-string
0496-next-greater-element-i
0567-permutation-in-string
0594-longest-harmonious-subsequence
0621-task-scheduler
0896-smallest-subtree-with-all-the-deepest-nodes
0940-fruit-into-baskets
1023-time-based-key-value-store
1423-maximum-number-of-occurrences-of-a-substring
1469-minimum-number-of-steps-to-make-two-strings-anagram
1547-destination-city
1798-max-number-of-k-sum-pairs
2372-rearrange-characters-to-make-target-string
2428-equal-row-and-column-pairs
2461-amount-of-time-for-binary-tree-to-be-infected
3329-find-the-length-of-the-longest-common-prefix

Two Pointers

0005-longest-palindromic-substring
0011-container-with-most-water
0015-3sum
0016-3sum-closest
0018-4sum
0019-remove-nth-node-from-end-of-list
0026-remove-duplicates-from-sorted-array
0042-trapping-rain-water
0061-rotate-list
0075-sort-colors
0086-partition-list
0088-merge-sorted-array
0125-valid-palindrome
0141-linked-list-cycle
0143-reorder-list
0167-two-sum-ii-input-array-is-sorted
0283-move-zeroes
0287-find-the-duplicate-number
0344-reverse-string
0556-next-greater-element-iii
0567-permutation-in-string
0611-valid-triangle-number
0680-valid-palindrome-ii
0908-middle-of-the-linked-list
1019-squares-of-a-sorted-array
1798-max-number-of-k-sum-pairs
1894-merge-strings-alternately

String

0003-longest-substring-without-repeating-characters
0005-longest-palindromic-substring
0014-longest-common-prefix
0017-letter-combinations-of-a-phone-number
0020-valid-parentheses
0022-generate-parentheses
0049-group-anagrams
0079-word-search
0125-valid-palindrome
0131-palindrome-partitioning
0208-implement-trie-prefix-tree
0211-design-add-and-search-words-data-structure
0212-word-search-ii
0242-valid-anagram
0344-reverse-string
0383-ransom-note
0394-decode-string
0409-longest-palindrome
0412-fizz-buzz
0424-longest-repeating-character-replacement
0438-find-all-anagrams-in-a-string
0556-next-greater-element-iii
0567-permutation-in-string
0678-valid-parenthesis-string
0680-valid-palindrome-ii
0886-score-of-parentheses
1023-time-based-key-value-store
1423-maximum-number-of-occurrences-of-a-substring
1469-minimum-number-of-steps-to-make-two-strings-anagram
1547-destination-city
1567-maximum-number-of-vowels-in-a-substring-of-given-length
1823-determine-if-string-halves-are-alike
1894-merge-strings-alternately
2292-counting-words-with-a-given-prefix
2337-remove-digit-from-number-to-maximize-result
2372-rearrange-characters-to-make-target-string
2470-removing-stars-from-a-string
2496-count-days-spent-together
3309-count-prefix-and-suffix-pairs-i
3329-find-the-length-of-the-longest-common-prefix
3379-score-of-a-string

Linked List

0002-add-two-numbers
0019-remove-nth-node-from-end-of-list
0021-merge-two-sorted-lists
0024-swap-nodes-in-pairs
0061-rotate-list
0086-partition-list
0138-copy-list-with-random-pointer
0141-linked-list-cycle
0143-reorder-list
0146-lru-cache
0203-remove-linked-list-elements
0206-reverse-linked-list
0328-odd-even-linked-list
0355-design-twitter
0908-middle-of-the-linked-list

Recursion

0002-add-two-numbers
0021-merge-two-sorted-lists
0024-swap-nodes-in-pairs
0143-reorder-list
0203-remove-linked-list-elements
0206-reverse-linked-list
0394-decode-string
1013-fibonacci-number

Tree

0094-binary-tree-inorder-traversal
0098-validate-binary-search-tree
0100-same-tree
0101-symmetric-tree
0102-binary-tree-level-order-traversal
0103-binary-tree-zigzag-level-order-traversal
0104-maximum-depth-of-binary-tree
0105-construct-binary-tree-from-preorder-and-inorder-traversal
0107-binary-tree-level-order-traversal-ii
0110-balanced-binary-tree
0111-minimum-depth-of-binary-tree
0112-path-sum
0144-binary-tree-preorder-traversal
0199-binary-tree-right-side-view
0222-count-complete-tree-nodes
0226-invert-binary-tree
0230-kth-smallest-element-in-a-bst
0235-lowest-common-ancestor-of-a-binary-search-tree
0530-minimum-absolute-difference-in-bst
0543-diameter-of-binary-tree
0572-subtree-of-another-tree
0617-merge-two-binary-trees
0789-kth-largest-element-in-a-stream
0896-smallest-subtree-with-all-the-deepest-nodes
1005-univalued-binary-tree
1035-cousins-in-binary-tree
1544-count-good-nodes-in-binary-tree
2461-amount-of-time-for-binary-tree-to-be-infected

Depth-First Search

0079-word-search
0094-binary-tree-inorder-traversal
0098-validate-binary-search-tree
0100-same-tree
0101-symmetric-tree
0104-maximum-depth-of-binary-tree
0110-balanced-binary-tree
0111-minimum-depth-of-binary-tree
0112-path-sum
0130-surrounded-regions
0133-clone-graph
0144-binary-tree-preorder-traversal
0199-binary-tree-right-side-view
0200-number-of-islands
0207-course-schedule
0210-course-schedule-ii
0211-design-add-and-search-words-data-structure
0226-invert-binary-tree
0230-kth-smallest-element-in-a-bst
0235-lowest-common-ancestor-of-a-binary-search-tree
0417-pacific-atlantic-water-flow
0419-battleships-in-a-board
0463-island-perimeter
0530-minimum-absolute-difference-in-bst
0543-diameter-of-binary-tree
0572-subtree-of-another-tree
0617-merge-two-binary-trees
0684-redundant-connection
0695-max-area-of-island
0733-flood-fill
0896-smallest-subtree-with-all-the-deepest-nodes
1005-univalued-binary-tree
1035-cousins-in-binary-tree
1073-number-of-enclaves
1544-count-good-nodes-in-binary-tree
2035-count-sub-islands
2461-amount-of-time-for-binary-tree-to-be-infected

Breadth-First Search

0100-same-tree
0101-symmetric-tree
0102-binary-tree-level-order-traversal
0103-binary-tree-zigzag-level-order-traversal
0104-maximum-depth-of-binary-tree
0107-binary-tree-level-order-traversal-ii
0111-minimum-depth-of-binary-tree
0112-path-sum
0130-surrounded-regions
0133-clone-graph
0199-binary-tree-right-side-view
0200-number-of-islands
0207-course-schedule
0210-course-schedule-ii
0226-invert-binary-tree
0417-pacific-atlantic-water-flow
0463-island-perimeter
0530-minimum-absolute-difference-in-bst
0542-01-matrix
0617-merge-two-binary-trees
0684-redundant-connection
0695-max-area-of-island
0733-flood-fill
0896-smallest-subtree-with-all-the-deepest-nodes
1005-univalued-binary-tree
1035-cousins-in-binary-tree
1036-rotting-oranges
1073-number-of-enclaves
1117-as-far-from-land-as-possible
1171-shortest-path-in-binary-matrix
1544-count-good-nodes-in-binary-tree
1876-map-of-highest-peak
2035-count-sub-islands
2461-amount-of-time-for-binary-tree-to-be-infected

Binary Tree

0094-binary-tree-inorder-traversal
0098-validate-binary-search-tree
0100-same-tree
0101-symmetric-tree
0102-binary-tree-level-order-traversal
0103-binary-tree-zigzag-level-order-traversal
0104-maximum-depth-of-binary-tree
0105-construct-binary-tree-from-preorder-and-inorder-traversal
0107-binary-tree-level-order-traversal-ii
0110-balanced-binary-tree
0111-minimum-depth-of-binary-tree
0112-path-sum
0144-binary-tree-preorder-traversal
0199-binary-tree-right-side-view
0222-count-complete-tree-nodes
0226-invert-binary-tree
0230-kth-smallest-element-in-a-bst
0235-lowest-common-ancestor-of-a-binary-search-tree
0530-minimum-absolute-difference-in-bst
0543-diameter-of-binary-tree
0572-subtree-of-another-tree
0617-merge-two-binary-trees
0789-kth-largest-element-in-a-stream
0896-smallest-subtree-with-all-the-deepest-nodes
1005-univalued-binary-tree
1035-cousins-in-binary-tree
1544-count-good-nodes-in-binary-tree
2461-amount-of-time-for-binary-tree-to-be-infected

Sorting

0015-3sum
0016-3sum-closest
0018-4sum
0049-group-anagrams
0056-merge-intervals
0075-sort-colors
0088-merge-sorted-array
0169-majority-element
0215-kth-largest-element-in-an-array
0217-contains-duplicate
0242-valid-anagram
0347-top-k-frequent-elements
0435-non-overlapping-intervals
0452-minimum-number-of-arrows-to-burst-balloons
0594-longest-harmonious-subsequence
0611-valid-triangle-number
0621-task-scheduler
0883-car-fleet
1014-k-closest-points-to-origin
1019-squares-of-a-sorted-array
1675-magnetic-force-between-two-balls
1798-max-number-of-k-sum-pairs

Prefix Sum

0209-minimum-size-subarray-sum
0238-product-of-array-except-self
0410-split-array-largest-sum
1046-max-consecutive-ones-iii

Union Find

0128-longest-consecutive-sequence
0130-surrounded-regions
0200-number-of-islands
0684-redundant-connection
0695-max-area-of-island
1073-number-of-enclaves
2035-count-sub-islands

Divide and Conquer

0053-maximum-subarray
0105-construct-binary-tree-from-preorder-and-inorder-traversal
0169-majority-element
0215-kth-largest-element-in-an-array
0347-top-k-frequent-elements
1014-k-closest-points-to-origin

Heap (Priority Queue)

0215-kth-largest-element-in-an-array
0347-top-k-frequent-elements
0355-design-twitter
0621-task-scheduler
0789-kth-largest-element-in-a-stream
1014-k-closest-points-to-origin
1127-last-stone-weight

Bucket Sort

0347-top-k-frequent-elements

Counting

0169-majority-element
0347-top-k-frequent-elements
0383-ransom-note
0594-longest-harmonious-subsequence
0621-task-scheduler
1469-minimum-number-of-steps-to-make-two-strings-anagram
1823-determine-if-string-halves-are-alike
2372-rearrange-characters-to-make-target-string

Quickselect

0215-kth-largest-element-in-an-array
0347-top-k-frequent-elements
1014-k-closest-points-to-origin

Greedy

0011-container-with-most-water
0045-jump-game-ii
0055-jump-game
0122-best-time-to-buy-and-sell-stock-ii
0134-gas-station
0409-longest-palindrome
0410-split-array-largest-sum
0435-non-overlapping-intervals
0452-minimum-number-of-arrows-to-burst-balloons
0605-can-place-flowers
0611-valid-triangle-number
0621-task-scheduler
0678-valid-parenthesis-string
0680-valid-palindrome-ii
2337-remove-digit-from-number-to-maximize-result

Stack

0020-valid-parentheses
0042-trapping-rain-water
0084-largest-rectangle-in-histogram
0094-binary-tree-inorder-traversal
0143-reorder-list
0144-binary-tree-preorder-traversal
0150-evaluate-reverse-polish-notation
0155-min-stack
0232-implement-queue-using-stacks
0394-decode-string
0496-next-greater-element-i
0503-next-greater-element-ii
0678-valid-parenthesis-string
0735-asteroid-collision
0739-daily-temperatures
0883-car-fleet
0886-score-of-parentheses
0937-online-stock-span
1570-final-prices-with-a-special-discount-in-a-shop
2470-removing-stars-from-a-string

Dynamic Programming

0005-longest-palindromic-substring
0022-generate-parentheses
0042-trapping-rain-water
0045-jump-game-ii
0053-maximum-subarray
0055-jump-game
0070-climbing-stairs
0121-best-time-to-buy-and-sell-stock
0122-best-time-to-buy-and-sell-stock-ii
0131-palindrome-partitioning
0152-maximum-product-subarray
0410-split-array-largest-sum
0435-non-overlapping-intervals
0542-01-matrix
0678-valid-parenthesis-string
1013-fibonacci-number
1117-as-far-from-land-as-possible
1586-longest-subarray-of-1s-after-deleting-one-element

Backtracking

0017-letter-combinations-of-a-phone-number
0022-generate-parentheses
0039-combination-sum
0040-combination-sum-ii
0046-permutations
0051-n-queens
0078-subsets
0079-word-search
0090-subsets-ii
0131-palindrome-partitioning
0212-word-search-ii

Math

0002-add-two-numbers
0048-rotate-image
0070-climbing-stairs
0150-evaluate-reverse-polish-notation
0412-fizz-buzz
0556-next-greater-element-iii
1013-fibonacci-number
1014-k-closest-points-to-origin
1950-sign-of-the-product-of-an-array
2496-count-days-spent-together

Sliding Window

0003-longest-substring-without-repeating-characters
0209-minimum-size-subarray-sum
0424-longest-repeating-character-replacement
0438-find-all-anagrams-in-a-string
0567-permutation-in-string
0594-longest-harmonious-subsequence
0643-maximum-average-subarray-i
0940-fruit-into-baskets
1046-max-consecutive-ones-iii
1423-maximum-number-of-occurrences-of-a-substring
1567-maximum-number-of-vowels-in-a-substring-of-given-length
1586-longest-subarray-of-1s-after-deleting-one-element

Monotonic Stack

0042-trapping-rain-water
0084-largest-rectangle-in-histogram
0496-next-greater-element-i
0503-next-greater-element-ii
0739-daily-temperatures
0883-car-fleet
0937-online-stock-span
1570-final-prices-with-a-special-discount-in-a-shop

Design

0146-lru-cache
0155-min-stack
0208-implement-trie-prefix-tree
0211-design-add-and-search-words-data-structure
0232-implement-queue-using-stacks
0355-design-twitter
0729-my-calendar-i
0789-kth-largest-element-in-a-stream
0937-online-stock-span
1023-time-based-key-value-store

Binary Search

0033-search-in-rotated-sorted-array
0034-find-first-and-last-position-of-element-in-sorted-array
0074-search-a-2d-matrix
0153-find-minimum-in-rotated-sorted-array
0154-find-minimum-in-rotated-sorted-array-ii
0167-two-sum-ii-input-array-is-sorted
0209-minimum-size-subarray-sum
0222-count-complete-tree-nodes
0287-find-the-duplicate-number
0410-split-array-largest-sum
0611-valid-triangle-number
0729-my-calendar-i
0792-binary-search
0907-koko-eating-bananas
1023-time-based-key-value-store
1046-max-consecutive-ones-iii
1056-capacity-to-ship-packages-within-d-days
1408-find-the-smallest-divisor-given-a-threshold
1605-minimum-number-of-days-to-make-m-bouquets
1675-magnetic-force-between-two-balls
2665-minimum-time-to-repair-cars

Matrix

0036-valid-sudoku
0048-rotate-image
0054-spiral-matrix
0073-set-matrix-zeroes
0074-search-a-2d-matrix
0079-word-search
0130-surrounded-regions
0200-number-of-islands
0212-word-search-ii
0417-pacific-atlantic-water-flow
0419-battleships-in-a-board
0463-island-perimeter
0542-01-matrix
0695-max-area-of-island
0733-flood-fill
1036-rotting-oranges
1073-number-of-enclaves
1117-as-far-from-land-as-possible
1171-shortest-path-in-binary-matrix
1876-map-of-highest-peak
2035-count-sub-islands
2428-equal-row-and-column-pairs

Bit Manipulation

0078-subsets
0090-subsets-ii
0222-count-complete-tree-nodes
0287-find-the-duplicate-number

Binary Search Tree

0098-validate-binary-search-tree
0230-kth-smallest-element-in-a-bst
0235-lowest-common-ancestor-of-a-binary-search-tree
0530-minimum-absolute-difference-in-bst
0789-kth-largest-element-in-a-stream

Simulation

0054-spiral-matrix
0412-fizz-buzz
0735-asteroid-collision
2058-concatenation-of-array
2428-equal-row-and-column-pairs
2470-removing-stars-from-a-string

Data Stream

0789-kth-largest-element-in-a-stream
0937-online-stock-span

Trie

0014-longest-common-prefix
0208-implement-trie-prefix-tree
0211-design-add-and-search-words-data-structure
0212-word-search-ii
3309-count-prefix-and-suffix-pairs-i
3329-find-the-length-of-the-longest-common-prefix

String Matching

0572-subtree-of-another-tree
2292-counting-words-with-a-given-prefix
3309-count-prefix-and-suffix-pairs-i

Rolling Hash

3309-count-prefix-and-suffix-pairs-i

Hash Function

0572-subtree-of-another-tree
3309-count-prefix-and-suffix-pairs-i

Graph

0133-clone-graph
0207-course-schedule
0210-course-schedule-ii
0684-redundant-connection

Topological Sort

0207-course-schedule
0210-course-schedule-ii

Doubly-Linked List

0146-lru-cache

Memoization

0070-climbing-stairs
1013-fibonacci-number

Enumeration

2337-remove-digit-from-number-to-maximize-result

Queue

0232-implement-queue-using-stacks

Geometry

1014-k-closest-points-to-origin

Segment Tree

0729-my-calendar-i

Ordered Set

0729-my-calendar-i