LeetCode

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

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LeetCode Topics

Array

0001-two-sum
0011-container-with-most-water
0015-3sum
0016-3sum-closest
0033-search-in-rotated-sorted-array
0034-find-first-and-last-position-of-element-in-sorted-array
0039-combination-sum
0045-jump-game-ii
0048-rotate-image
0049-group-anagrams
0053-maximum-subarray
0056-merge-intervals
0063-unique-paths-ii
0064-minimum-path-sum
0073-set-matrix-zeroes
0075-sort-colors
0078-subsets
0088-merge-sorted-array
0106-construct-binary-tree-from-inorder-and-postorder-traversal
0108-convert-sorted-array-to-binary-search-tree
0118-pascals-triangle
0120-triangle
0121-best-time-to-buy-and-sell-stock
0128-longest-consecutive-sequence
0149-max-points-on-a-line
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
0198-house-robber
0200-number-of-islands
0209-minimum-size-subarray-sum
0213-house-robber-ii
0215-kth-largest-element-in-an-array
0217-contains-duplicate
0229-majority-element-ii
0238-product-of-array-except-self
0239-sliding-window-maximum
0268-missing-number
0287-find-the-duplicate-number
0300-longest-increasing-subsequence
0303-range-sum-query-immutable
0322-coin-change
0347-top-k-frequent-elements
0416-partition-equal-subset-sum
0503-next-greater-element-ii
0540-single-element-in-a-sorted-array
0713-subarray-product-less-than-k
0735-asteroid-collision
0739-daily-temperatures
0907-koko-eating-bananas
0925-construct-binary-tree-from-preorder-and-postorder-traversal
0954-maximum-sum-circular-subarray
0967-minimum-falling-path-sum
1050-construct-binary-search-tree-from-preorder-traversal
1224-minimum-falling-path-sum-ii
1335-maximum-candies-allocated-to-k-children
1631-number-of-sub-arrays-with-odd-sum
1849-maximum-absolute-sum-of-any-subarray
1983-maximum-population-year
2107-find-unique-binary-string
2160-minimum-operations-to-make-a-uni-value-grid
2220-find-all-possible-recipes-from-given-supplies
2255-minimum-swaps-to-group-all-1s-together-ii
2265-partition-array-according-to-given-pivot
2308-divide-array-into-equal-pairs
2448-count-number-of-bad-pairs
2478-longest-nice-subarray
2551-apply-operations-to-an-array
2564-most-profitable-path-in-a-tree
2588-maximum-number-of-points-from-grid-queries
2614-maximum-count-of-positive-integer-and-negative-integer
2665-minimum-time-to-repair-cars
2681-put-marbles-in-bags
2690-house-robber-iv
2707-merge-two-2d-arrays-by-summing-values
2888-minimum-index-of-a-valid-split
3001-apply-operations-to-maximize-score
3227-find-missing-and-repeated-values
3242-count-elements-with-maximum-frequency
3332-minimum-operations-to-exceed-threshold-value-ii
3348-minimum-cost-walk-in-weighted-graph
3372-longest-strictly-increasing-or-strictly-decreasing-subarray
3398-make-a-square-with-the-same-color
3430-count-days-without-meetings
3475-minimum-operations-to-make-binary-array-elements-equal-to-one-i
3483-alternating-groups-ii
3501-delete-nodes-from-linked-list-present-in-array
3541-report-spam-message
3643-zero-array-transformation-ii
3657-check-if-grid-can-be-cut-into-sections

Binary Search

0033-search-in-rotated-sorted-array
0034-find-first-and-last-position-of-element-in-sorted-array
0069-sqrtx
0153-find-minimum-in-rotated-sorted-array
0162-find-peak-element
0167-two-sum-ii-input-array-is-sorted
0209-minimum-size-subarray-sum
0268-missing-number
0287-find-the-duplicate-number
0300-longest-increasing-subsequence
0374-guess-number-higher-or-lower
0540-single-element-in-a-sorted-array
0713-subarray-product-less-than-k
0907-koko-eating-bananas
1335-maximum-candies-allocated-to-k-children
2614-maximum-count-of-positive-integer-and-negative-integer
2665-minimum-time-to-repair-cars
2690-house-robber-iv
3643-zero-array-transformation-ii

Hash Table

0001-two-sum
0003-longest-substring-without-repeating-characters
0013-roman-to-integer
0049-group-anagrams
0073-set-matrix-zeroes
0076-minimum-window-substring
0106-construct-binary-tree-from-inorder-and-postorder-traversal
0128-longest-consecutive-sequence
0133-clone-graph
0138-copy-list-with-random-pointer
0141-linked-list-cycle
0142-linked-list-cycle-ii
0149-max-points-on-a-line
0160-intersection-of-two-linked-lists
0169-majority-element
0187-repeated-dna-sequences
0217-contains-duplicate
0229-majority-element-ii
0268-missing-number
0347-top-k-frequent-elements
0451-sort-characters-by-frequency
0768-partition-labels
0925-construct-binary-tree-from-preorder-and-postorder-traversal
1029-vertical-order-traversal-of-a-binary-tree
1387-find-elements-in-a-contaminated-binary-tree
1460-number-of-substrings-containing-all-three-characters
2107-find-unique-binary-string
2174-next-greater-numerically-balanced-number
2220-find-all-possible-recipes-from-given-supplies
2308-divide-array-into-equal-pairs
2427-first-letter-to-appear-twice
2448-count-number-of-bad-pairs
2461-amount-of-time-for-binary-tree-to-be-infected
2707-merge-two-2d-arrays-by-summing-values
2888-minimum-index-of-a-valid-split
3227-find-missing-and-repeated-values
3242-count-elements-with-maximum-frequency
3501-delete-nodes-from-linked-list-present-in-array
3541-report-spam-message
3569-count-of-substrings-containing-every-vowel-and-k-consonants-ii

Matrix

0048-rotate-image
0063-unique-paths-ii
0064-minimum-path-sum
0073-set-matrix-zeroes
0200-number-of-islands
0967-minimum-falling-path-sum
1224-minimum-falling-path-sum-ii
2160-minimum-operations-to-make-a-uni-value-grid
2588-maximum-number-of-points-from-grid-queries
3227-find-missing-and-repeated-values
3398-make-a-square-with-the-same-color

Dynamic Programming

0045-jump-game-ii
0053-maximum-subarray
0062-unique-paths
0063-unique-paths-ii
0064-minimum-path-sum
0070-climbing-stairs
0118-pascals-triangle
0120-triangle
0121-best-time-to-buy-and-sell-stock
0124-binary-tree-maximum-path-sum
0152-maximum-product-subarray
0198-house-robber
0213-house-robber-ii
0300-longest-increasing-subsequence
0322-coin-change
0337-house-robber-iii
0338-counting-bits
0416-partition-equal-subset-sum
0516-longest-palindromic-subsequence
0954-maximum-sum-circular-subarray
0967-minimum-falling-path-sum
1170-shortest-common-supersequence
1224-minimum-falling-path-sum-ii
1250-longest-common-subsequence
1631-number-of-sub-arrays-with-odd-sum
1849-maximum-absolute-sum-of-any-subarray
2090-number-of-ways-to-arrive-at-destination

Divide and Conquer

0023-merge-k-sorted-lists
0053-maximum-subarray
0106-construct-binary-tree-from-inorder-and-postorder-traversal
0108-convert-sorted-array-to-binary-search-tree
0169-majority-element
0191-number-of-1-bits
0215-kth-largest-element-in-an-array
0347-top-k-frequent-elements
0925-construct-binary-tree-from-preorder-and-postorder-traversal
0954-maximum-sum-circular-subarray

Two Pointers

0011-container-with-most-water
0015-3sum
0016-3sum-closest
0061-rotate-list
0075-sort-colors
0082-remove-duplicates-from-sorted-list-ii
0088-merge-sorted-array
0141-linked-list-cycle
0142-linked-list-cycle-ii
0143-reorder-list
0160-intersection-of-two-linked-lists
0167-two-sum-ii-input-array-is-sorted
0234-palindrome-linked-list
0287-find-the-duplicate-number
0768-partition-labels
0908-middle-of-the-linked-list
2216-delete-the-middle-node-of-a-linked-list
2265-partition-array-according-to-given-pivot
2551-apply-operations-to-an-array
2588-maximum-number-of-points-from-grid-queries
2707-merge-two-2d-arrays-by-summing-values

Sorting

0015-3sum
0016-3sum-closest
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
0229-majority-element-ii
0268-missing-number
0347-top-k-frequent-elements
0451-sort-characters-by-frequency
1029-vertical-order-traversal-of-a-binary-tree
2160-minimum-operations-to-make-a-uni-value-grid
2588-maximum-number-of-points-from-grid-queries
2681-put-marbles-in-bags
2888-minimum-index-of-a-valid-split
3001-apply-operations-to-maximize-score
3430-count-days-without-meetings
3657-check-if-grid-can-be-cut-into-sections

Tree

0094-binary-tree-inorder-traversal
0098-validate-binary-search-tree
0100-same-tree
0102-binary-tree-level-order-traversal
0103-binary-tree-zigzag-level-order-traversal
0104-maximum-depth-of-binary-tree
0106-construct-binary-tree-from-inorder-and-postorder-traversal
0108-convert-sorted-array-to-binary-search-tree
0110-balanced-binary-tree
0112-path-sum
0114-flatten-binary-tree-to-linked-list
0116-populating-next-right-pointers-in-each-node
0124-binary-tree-maximum-path-sum
0144-binary-tree-preorder-traversal
0145-binary-tree-postorder-traversal
0199-binary-tree-right-side-view
0226-invert-binary-tree
0230-kth-smallest-element-in-a-bst
0235-lowest-common-ancestor-of-a-binary-search-tree
0236-lowest-common-ancestor-of-a-binary-tree
0337-house-robber-iii
0404-sum-of-left-leaves
0543-diameter-of-binary-tree
0637-average-of-levels-in-binary-tree
0784-insert-into-a-binary-search-tree
0925-construct-binary-tree-from-preorder-and-postorder-traversal
1029-vertical-order-traversal-of-a-binary-tree
1050-construct-binary-search-tree-from-preorder-traversal
1093-recover-a-tree-from-preorder-traversal
1387-find-elements-in-a-contaminated-binary-tree
2461-amount-of-time-for-binary-tree-to-be-infected
2564-most-profitable-path-in-a-tree

Depth-First Search

0094-binary-tree-inorder-traversal
0098-validate-binary-search-tree
0100-same-tree
0104-maximum-depth-of-binary-tree
0110-balanced-binary-tree
0112-path-sum
0114-flatten-binary-tree-to-linked-list
0116-populating-next-right-pointers-in-each-node
0124-binary-tree-maximum-path-sum
0133-clone-graph
0144-binary-tree-preorder-traversal
0145-binary-tree-postorder-traversal
0199-binary-tree-right-side-view
0200-number-of-islands
0226-invert-binary-tree
0230-kth-smallest-element-in-a-bst
0235-lowest-common-ancestor-of-a-binary-search-tree
0236-lowest-common-ancestor-of-a-binary-tree
0337-house-robber-iii
0404-sum-of-left-leaves
0543-diameter-of-binary-tree
0637-average-of-levels-in-binary-tree
0820-find-eventual-safe-states
1029-vertical-order-traversal-of-a-binary-tree
1093-recover-a-tree-from-preorder-traversal
1387-find-elements-in-a-contaminated-binary-tree
2461-amount-of-time-for-binary-tree-to-be-infected
2564-most-profitable-path-in-a-tree
2793-count-the-number-of-complete-components

Binary Tree

0094-binary-tree-inorder-traversal
0098-validate-binary-search-tree
0100-same-tree
0102-binary-tree-level-order-traversal
0103-binary-tree-zigzag-level-order-traversal
0104-maximum-depth-of-binary-tree
0106-construct-binary-tree-from-inorder-and-postorder-traversal
0108-convert-sorted-array-to-binary-search-tree
0110-balanced-binary-tree
0112-path-sum
0114-flatten-binary-tree-to-linked-list
0116-populating-next-right-pointers-in-each-node
0124-binary-tree-maximum-path-sum
0144-binary-tree-preorder-traversal
0145-binary-tree-postorder-traversal
0199-binary-tree-right-side-view
0226-invert-binary-tree
0230-kth-smallest-element-in-a-bst
0235-lowest-common-ancestor-of-a-binary-search-tree
0236-lowest-common-ancestor-of-a-binary-tree
0337-house-robber-iii
0404-sum-of-left-leaves
0543-diameter-of-binary-tree
0637-average-of-levels-in-binary-tree
0784-insert-into-a-binary-search-tree
0925-construct-binary-tree-from-preorder-and-postorder-traversal
1029-vertical-order-traversal-of-a-binary-tree
1050-construct-binary-search-tree-from-preorder-traversal
1093-recover-a-tree-from-preorder-traversal
1387-find-elements-in-a-contaminated-binary-tree
2461-amount-of-time-for-binary-tree-to-be-infected

Math

0013-roman-to-integer
0029-divide-two-integers
0048-rotate-image
0050-powx-n
0062-unique-paths
0069-sqrtx
0070-climbing-stairs
0149-max-points-on-a-line
0268-missing-number
0326-power-of-three
0342-power-of-four
1631-number-of-sub-arrays-with-odd-sum
1889-check-if-number-is-a-sum-of-powers-of-three
2160-minimum-operations-to-make-a-uni-value-grid
2174-next-greater-numerically-balanced-number
2448-count-number-of-bad-pairs
2610-closest-prime-numbers-in-range
2649-count-total-number-of-colored-cells
3001-apply-operations-to-maximize-score
3227-find-missing-and-repeated-values

Bit Manipulation

0029-divide-two-integers
0078-subsets
0187-repeated-dna-sequences
0191-number-of-1-bits
0201-bitwise-and-of-numbers-range
0268-missing-number
0287-find-the-duplicate-number
0338-counting-bits
0342-power-of-four
2308-divide-array-into-equal-pairs
2427-first-letter-to-appear-twice
2478-longest-nice-subarray
3348-minimum-cost-walk-in-weighted-graph
3475-minimum-operations-to-make-binary-array-elements-equal-to-one-i

Recursion

0021-merge-two-sorted-lists
0025-reverse-nodes-in-k-group
0050-powx-n
0143-reorder-list
0206-reverse-linked-list
0234-palindrome-linked-list
0326-power-of-three
0342-power-of-four

Counting

0169-majority-element
0229-majority-element-ii
0347-top-k-frequent-elements
0451-sort-characters-by-frequency
1983-maximum-population-year
2174-next-greater-numerically-balanced-number
2308-divide-array-into-equal-pairs
2427-first-letter-to-appear-twice
2448-count-number-of-bad-pairs
2614-maximum-count-of-positive-integer-and-negative-integer
3242-count-elements-with-maximum-frequency

Combinatorics

0062-unique-paths

Stack

0020-valid-parentheses
0094-binary-tree-inorder-traversal
0114-flatten-binary-tree-to-linked-list
0143-reorder-list
0144-binary-tree-preorder-traversal
0145-binary-tree-postorder-traversal
0155-min-stack
0225-implement-stack-using-queues
0232-implement-queue-using-stacks
0234-palindrome-linked-list
0402-remove-k-digits
0503-next-greater-element-ii
0735-asteroid-collision
0739-daily-temperatures
0937-online-stock-span
1050-construct-binary-search-tree-from-preorder-traversal
2021-remove-all-occurrences-of-a-substring
3001-apply-operations-to-maximize-score
3447-clear-digits

Design

0155-min-stack
0225-implement-stack-using-queues
0232-implement-queue-using-stacks
0303-range-sum-query-immutable
0838-design-linked-list
0937-online-stock-span
1387-find-elements-in-a-contaminated-binary-tree

Monotonic Stack

0402-remove-k-digits
0503-next-greater-element-ii
0739-daily-temperatures
0937-online-stock-span
1050-construct-binary-search-tree-from-preorder-traversal
3001-apply-operations-to-maximize-score

Data Stream

0937-online-stock-span

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
0112-path-sum
0116-populating-next-right-pointers-in-each-node
0133-clone-graph
0199-binary-tree-right-side-view
0200-number-of-islands
0226-invert-binary-tree
0322-coin-change
0404-sum-of-left-leaves
0637-average-of-levels-in-binary-tree
0820-find-eventual-safe-states
1029-vertical-order-traversal-of-a-binary-tree
1387-find-elements-in-a-contaminated-binary-tree
2461-amount-of-time-for-binary-tree-to-be-infected
2564-most-profitable-path-in-a-tree
2588-maximum-number-of-points-from-grid-queries
2793-count-the-number-of-complete-components

Union Find

0128-longest-consecutive-sequence
0200-number-of-islands
2588-maximum-number-of-points-from-grid-queries
2793-count-the-number-of-complete-components
3348-minimum-cost-walk-in-weighted-graph

Graph

0133-clone-graph
0820-find-eventual-safe-states
2090-number-of-ways-to-arrive-at-destination
2220-find-all-possible-recipes-from-given-supplies
2564-most-profitable-path-in-a-tree
2793-count-the-number-of-complete-components
3348-minimum-cost-walk-in-weighted-graph

Topological Sort

0820-find-eventual-safe-states
2090-number-of-ways-to-arrive-at-destination
2220-find-all-possible-recipes-from-given-supplies

Prefix Sum

0209-minimum-size-subarray-sum
0238-product-of-array-except-self
0303-range-sum-query-immutable
0713-subarray-product-less-than-k
1631-number-of-sub-arrays-with-odd-sum
1983-maximum-population-year
3475-minimum-operations-to-make-binary-array-elements-equal-to-one-i
3643-zero-array-transformation-ii

Enumeration

2174-next-greater-numerically-balanced-number
3398-make-a-square-with-the-same-color

Linked List

0021-merge-two-sorted-lists
0023-merge-k-sorted-lists
0025-reverse-nodes-in-k-group
0061-rotate-list
0082-remove-duplicates-from-sorted-list-ii
0083-remove-duplicates-from-sorted-list
0092-reverse-linked-list-ii
0114-flatten-binary-tree-to-linked-list
0116-populating-next-right-pointers-in-each-node
0138-copy-list-with-random-pointer
0141-linked-list-cycle
0142-linked-list-cycle-ii
0143-reorder-list
0160-intersection-of-two-linked-lists
0206-reverse-linked-list
0234-palindrome-linked-list
0328-odd-even-linked-list
0725-split-linked-list-in-parts
0838-design-linked-list
0908-middle-of-the-linked-list
2216-delete-the-middle-node-of-a-linked-list
3501-delete-nodes-from-linked-list-present-in-array

Backtracking

0039-combination-sum
0078-subsets
2107-find-unique-binary-string
2174-next-greater-numerically-balanced-number

Interactive

0374-guess-number-higher-or-lower

String

0003-longest-substring-without-repeating-characters
0013-roman-to-integer
0020-valid-parentheses
0038-count-and-say
0049-group-anagrams
0076-minimum-window-substring
0187-repeated-dna-sequences
0402-remove-k-digits
0451-sort-characters-by-frequency
0516-longest-palindromic-subsequence
0768-partition-labels
1093-recover-a-tree-from-preorder-traversal
1170-shortest-common-supersequence
1250-longest-common-subsequence
1460-number-of-substrings-containing-all-three-characters
2021-remove-all-occurrences-of-a-substring
2107-find-unique-binary-string
2220-find-all-possible-recipes-from-given-supplies
2427-first-letter-to-appear-twice
2463-minimum-recolors-to-get-k-consecutive-black-blocks
3447-clear-digits
3541-report-spam-message
3569-count-of-substrings-containing-every-vowel-and-k-consonants-ii

Simulation

0735-asteroid-collision
2021-remove-all-occurrences-of-a-substring
2265-partition-array-according-to-given-pivot
2551-apply-operations-to-an-array
3332-minimum-operations-to-exceed-threshold-value-ii
3447-clear-digits

Heap (Priority Queue)

0023-merge-k-sorted-lists
0215-kth-largest-element-in-an-array
0239-sliding-window-maximum
0347-top-k-frequent-elements
0451-sort-characters-by-frequency
2588-maximum-number-of-points-from-grid-queries
2681-put-marbles-in-bags
3332-minimum-operations-to-exceed-threshold-value-ii

Binary Search Tree

0098-validate-binary-search-tree
0108-convert-sorted-array-to-binary-search-tree
0230-kth-smallest-element-in-a-bst
0235-lowest-common-ancestor-of-a-binary-search-tree
0784-insert-into-a-binary-search-tree
1050-construct-binary-search-tree-from-preorder-traversal

Queue

0225-implement-stack-using-queues
0232-implement-queue-using-stacks
0239-sliding-window-maximum
0954-maximum-sum-circular-subarray
3475-minimum-operations-to-make-binary-array-elements-equal-to-one-i

Monotonic Queue

0239-sliding-window-maximum
0954-maximum-sum-circular-subarray

Greedy

0011-container-with-most-water
0045-jump-game-ii
0402-remove-k-digits
0768-partition-labels
2681-put-marbles-in-bags
3001-apply-operations-to-maximize-score

Sliding Window

0003-longest-substring-without-repeating-characters
0076-minimum-window-substring
0187-repeated-dna-sequences
0209-minimum-size-subarray-sum
0239-sliding-window-maximum
0713-subarray-product-less-than-k
1460-number-of-substrings-containing-all-three-characters
2255-minimum-swaps-to-group-all-1s-together-ii
2463-minimum-recolors-to-get-k-consecutive-black-blocks
2478-longest-nice-subarray
3475-minimum-operations-to-make-binary-array-elements-equal-to-one-i
3483-alternating-groups-ii
3569-count-of-substrings-containing-every-vowel-and-k-consonants-ii

Bucket Sort

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

Quickselect

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

Database

0584-find-customer-referee
1258-article-views-i
1509-replace-employee-id-with-the-unique-identifier
1724-customer-who-visited-but-did-not-make-any-transactions
1827-invalid-tweets
1908-recyclable-and-low-fat-products

Number Theory

2610-closest-prime-numbers-in-range
3001-apply-operations-to-maximize-score

Shortest Path

2090-number-of-ways-to-arrive-at-destination

Rolling Hash

0187-repeated-dna-sequences

Hash Function

0187-repeated-dna-sequences

Memoization

0070-climbing-stairs

Geometry

0149-max-points-on-a-line

Merge Sort

0023-merge-k-sorted-lists