Leetcode

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
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
0063-unique-paths-ii
0064-minimum-path-sum
0066-plus-one
0068-text-justification
0073-set-matrix-zeroes
0074-search-a-2d-matrix
0078-subsets
0079-word-search
0080-remove-duplicates-from-sorted-array-ii
0081-search-in-rotated-sorted-array-ii
0084-largest-rectangle-in-histogram
0088-merge-sorted-array
0090-subsets-ii
0105-construct-binary-tree-from-preorder-and-inorder-traversal
0106-construct-binary-tree-from-inorder-and-postorder-traversal
0108-convert-sorted-array-to-binary-search-tree
0120-triangle
0121-best-time-to-buy-and-sell-stock
0122-best-time-to-buy-and-sell-stock-ii
0123-best-time-to-buy-and-sell-stock-iii
0128-longest-consecutive-sequence
0130-surrounded-regions
0134-gas-station
0135-candy
0136-single-number
0137-single-number-ii
0139-word-break
0149-max-points-on-a-line
0150-evaluate-reverse-polish-notation
0153-find-minimum-in-rotated-sorted-array
0154-find-minimum-in-rotated-sorted-array-ii
0162-find-peak-element
0167-two-sum-ii-input-array-is-sorted
0169-majority-element
0188-best-time-to-buy-and-sell-stock-iv
0189-rotate-array
0198-house-robber
0200-number-of-islands
0209-minimum-size-subarray-sum
0212-word-search-ii
0213-house-robber-ii
0215-kth-largest-element-in-an-array
0217-contains-duplicate
0219-contains-duplicate-ii
0221-maximal-square
0228-summary-ranges
0238-product-of-array-except-self
0239-sliding-window-maximum
0274-h-index
0287-find-the-duplicate-number
0289-game-of-life
0300-longest-increasing-subsequence
0309-best-time-to-buy-and-sell-stock-with-cooldown
0312-burst-balloons
0322-coin-change
0329-longest-increasing-path-in-a-matrix
0347-top-k-frequent-elements
0373-find-k-pairs-with-smallest-sums
0380-insert-delete-getrandom-o1
0399-evaluate-division
0416-partition-equal-subset-sum
0417-pacific-atlantic-water-flow
0435-non-overlapping-intervals
0452-minimum-number-of-arrows-to-burst-balloons
0494-target-sum
0502-ipo
0525-contiguous-array
0621-task-scheduler
0695-max-area-of-island
0704-binary-search
0718-maximum-length-of-repeated-subarray
0733-flood-fill
0739-daily-temperatures
0746-min-cost-climbing-stairs
0772-construct-quad-tree
0794-swim-in-rising-water
0829-subdomain-visit-count
0853-car-fleet
0875-koko-eating-bananas
0876-hand-of-straights
0945-snakes-and-ladders
0954-maximum-sum-circular-subarray
0973-k-closest-points-to-origin
1036-rotting-oranges
1046-last-stone-weight
1112-find-words-that-can-be-formed-by-characters
1422-divide-array-in-sets-of-k-consecutive-numbers
1706-min-cost-to-connect-all-points
1709-alert-using-same-key-card-three-or-more-times-in-a-one-hour-period
1757-minimum-jumps-to-reach-home
1851-minimum-interval-to-include-each-query
2026-merge-triplets-to-form-target-triplet
2254-check-if-every-row-and-column-contains-all-numbers

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
0061-rotate-list
0080-remove-duplicates-from-sorted-array-ii
0082-remove-duplicates-from-sorted-list-ii
0086-partition-list
0088-merge-sorted-array
0125-valid-palindrome
0141-linked-list-cycle
0143-reorder-list
0148-sort-list
0151-reverse-words-in-a-string
0167-two-sum-ii-input-array-is-sorted
0189-rotate-array
0202-happy-number
0287-find-the-duplicate-number
0295-find-median-from-data-stream
0392-is-subsequence
0567-permutation-in-string
0647-palindromic-substrings
0768-partition-labels

Sorting

0015-3sum
0049-group-anagrams
0056-merge-intervals
0088-merge-sorted-array
0148-sort-list
0169-majority-element
0215-kth-largest-element-in-an-array
0217-contains-duplicate
0242-valid-anagram
0274-h-index
0295-find-median-from-data-stream
0347-top-k-frequent-elements
0435-non-overlapping-intervals
0452-minimum-number-of-arrows-to-burst-balloons
0502-ipo
0621-task-scheduler
0853-car-fleet
0876-hand-of-straights
0973-k-closest-points-to-origin
1422-divide-array-in-sets-of-k-consecutive-numbers
1709-alert-using-same-key-card-three-or-more-times-in-a-one-hour-period
1851-minimum-interval-to-include-each-query

Hash Table

0001-two-sum
0003-longest-substring-without-repeating-characters
0012-integer-to-roman
0013-roman-to-integer
0017-letter-combinations-of-a-phone-number
0030-substring-with-concatenation-of-all-words
0036-valid-sudoku
0049-group-anagrams
0073-set-matrix-zeroes
0076-minimum-window-substring
0105-construct-binary-tree-from-preorder-and-inorder-traversal
0106-construct-binary-tree-from-inorder-and-postorder-traversal
0127-word-ladder
0128-longest-consecutive-sequence
0133-clone-graph
0138-copy-list-with-random-pointer
0139-word-break
0141-linked-list-cycle
0146-lru-cache
0149-max-points-on-a-line
0169-majority-element
0202-happy-number
0205-isomorphic-strings
0208-implement-trie-prefix-tree
0217-contains-duplicate
0219-contains-duplicate-ii
0242-valid-anagram
0290-word-pattern
0347-top-k-frequent-elements
0355-design-twitter
0380-insert-delete-getrandom-o1
0383-ransom-note
0424-longest-repeating-character-replacement
0433-minimum-genetic-mutation
0460-lfu-cache
0525-contiguous-array
0567-permutation-in-string
0621-task-scheduler
0768-partition-labels
0829-subdomain-visit-count
0876-hand-of-straights
0895-maximum-frequency-stack
0981-time-based-key-value-store
1112-find-words-that-can-be-formed-by-characters
1422-divide-array-in-sets-of-k-consecutive-numbers
1709-alert-using-same-key-card-three-or-more-times-in-a-one-hour-period
2254-check-if-every-row-and-column-contains-all-numbers

Divide and Conquer

0004-median-of-two-sorted-arrays
0023-merge-k-sorted-lists
0053-maximum-subarray
0105-construct-binary-tree-from-preorder-and-inorder-traversal
0106-construct-binary-tree-from-inorder-and-postorder-traversal
0108-convert-sorted-array-to-binary-search-tree
0148-sort-list
0169-majority-element
0190-reverse-bits
0191-number-of-1-bits
0215-kth-largest-element-in-an-array
0347-top-k-frequent-elements
0772-construct-quad-tree
0954-maximum-sum-circular-subarray
0973-k-closest-points-to-origin

Counting

0169-majority-element
0347-top-k-frequent-elements
0383-ransom-note
0621-task-scheduler
0829-subdomain-visit-count
1112-find-words-that-can-be-formed-by-characters

String

0003-longest-substring-without-repeating-characters
0005-longest-palindromic-substring
0006-zigzag-conversion
0010-regular-expression-matching
0012-integer-to-roman
0013-roman-to-integer
0014-longest-common-prefix
0017-letter-combinations-of-a-phone-number
0020-valid-parentheses
0022-generate-parentheses
0028-find-the-index-of-the-first-occurrence-in-a-string
0030-substring-with-concatenation-of-all-words
0049-group-anagrams
0058-length-of-last-word
0067-add-binary
0068-text-justification
0071-simplify-path
0072-edit-distance
0076-minimum-window-substring
0079-word-search
0097-interleaving-string
0115-distinct-subsequences
0125-valid-palindrome
0127-word-ladder
0131-palindrome-partitioning
0139-word-break
0151-reverse-words-in-a-string
0205-isomorphic-strings
0208-implement-trie-prefix-tree
0211-design-add-and-search-words-data-structure
0212-word-search-ii
0224-basic-calculator
0242-valid-anagram
0290-word-pattern
0297-serialize-and-deserialize-binary-tree
0383-ransom-note
0392-is-subsequence
0399-evaluate-division
0424-longest-repeating-character-replacement
0433-minimum-genetic-mutation
0567-permutation-in-string
0647-palindromic-substrings
0678-valid-parenthesis-string
0768-partition-labels
0829-subdomain-visit-count
0981-time-based-key-value-store
1112-find-words-that-can-be-formed-by-characters
1709-alert-using-same-key-card-three-or-more-times-in-a-one-hour-period

Dynamic Programming

0005-longest-palindromic-substring
0010-regular-expression-matching
0022-generate-parentheses
0042-trapping-rain-water
0045-jump-game-ii
0053-maximum-subarray
0055-jump-game
0062-unique-paths
0063-unique-paths-ii
0064-minimum-path-sum
0070-climbing-stairs
0072-edit-distance
0097-interleaving-string
0115-distinct-subsequences
0120-triangle
0121-best-time-to-buy-and-sell-stock
0122-best-time-to-buy-and-sell-stock-ii
0123-best-time-to-buy-and-sell-stock-iii
0124-binary-tree-maximum-path-sum
0131-palindrome-partitioning
0139-word-break
0188-best-time-to-buy-and-sell-stock-iv
0198-house-robber
0213-house-robber-ii
0221-maximal-square
0300-longest-increasing-subsequence
0309-best-time-to-buy-and-sell-stock-with-cooldown
0312-burst-balloons
0322-coin-change
0329-longest-increasing-path-in-a-matrix
0392-is-subsequence
0416-partition-equal-subset-sum
0435-non-overlapping-intervals
0494-target-sum
0647-palindromic-substrings
0678-valid-parenthesis-string
0718-maximum-length-of-repeated-subarray
0746-min-cost-climbing-stairs
0803-cheapest-flights-within-k-stops
0954-maximum-sum-circular-subarray
1757-minimum-jumps-to-reach-home

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
0154-find-minimum-in-rotated-sorted-array-ii
0162-find-peak-element
0167-two-sum-ii-input-array-is-sorted
0209-minimum-size-subarray-sum
0222-count-complete-tree-nodes
0287-find-the-duplicate-number
0300-longest-increasing-subsequence
0704-binary-search
0718-maximum-length-of-repeated-subarray
0794-swim-in-rising-water
0875-koko-eating-bananas
0981-time-based-key-value-store
1851-minimum-interval-to-include-each-query

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
0135-candy
0435-non-overlapping-intervals
0452-minimum-number-of-arrows-to-burst-balloons
0502-ipo
0621-task-scheduler
0678-valid-parenthesis-string
0768-partition-labels
0876-hand-of-straights
1422-divide-array-in-sets-of-k-consecutive-numbers
2026-merge-triplets-to-form-target-triplet

Sliding Window

0003-longest-substring-without-repeating-characters
0030-substring-with-concatenation-of-all-words
0076-minimum-window-substring
0209-minimum-size-subarray-sum
0219-contains-duplicate-ii
0239-sliding-window-maximum
0424-longest-repeating-character-replacement
0567-permutation-in-string
0718-maximum-length-of-repeated-subarray

Prefix Sum

0209-minimum-size-subarray-sum
0238-product-of-array-except-self
0525-contiguous-array

Queue

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

Monotonic Queue

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

Matrix

0036-valid-sudoku
0048-rotate-image
0054-spiral-matrix
0063-unique-paths-ii
0064-minimum-path-sum
0073-set-matrix-zeroes
0074-search-a-2d-matrix
0079-word-search
0130-surrounded-regions
0200-number-of-islands
0212-word-search-ii
0221-maximal-square
0289-game-of-life
0329-longest-increasing-path-in-a-matrix
0417-pacific-atlantic-water-flow
0695-max-area-of-island
0733-flood-fill
0772-construct-quad-tree
0794-swim-in-rising-water
0945-snakes-and-ladders
1036-rotting-oranges
2254-check-if-every-row-and-column-contains-all-numbers

Tree

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
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
0117-populating-next-right-pointers-in-each-node-ii
0124-binary-tree-maximum-path-sum
0129-sum-root-to-leaf-numbers
0173-binary-search-tree-iterator
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
0236-lowest-common-ancestor-of-a-binary-tree
0297-serialize-and-deserialize-binary-tree
0530-minimum-absolute-difference-in-bst
0543-diameter-of-binary-tree
0572-subtree-of-another-tree
0637-average-of-levels-in-binary-tree
0703-kth-largest-element-in-a-stream
0772-construct-quad-tree
1448-count-good-nodes-in-binary-tree

Depth-First Search

0079-word-search
0098-validate-binary-search-tree
0100-same-tree
0101-symmetric-tree
0104-maximum-depth-of-binary-tree
0110-balanced-binary-tree
0112-path-sum
0114-flatten-binary-tree-to-linked-list
0117-populating-next-right-pointers-in-each-node-ii
0124-binary-tree-maximum-path-sum
0129-sum-root-to-leaf-numbers
0130-surrounded-regions
0133-clone-graph
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
0236-lowest-common-ancestor-of-a-binary-tree
0297-serialize-and-deserialize-binary-tree
0329-longest-increasing-path-in-a-matrix
0332-reconstruct-itinerary
0399-evaluate-division
0417-pacific-atlantic-water-flow
0530-minimum-absolute-difference-in-bst
0543-diameter-of-binary-tree
0572-subtree-of-another-tree
0637-average-of-levels-in-binary-tree
0684-redundant-connection
0695-max-area-of-island
0733-flood-fill
0744-network-delay-time
0794-swim-in-rising-water
0803-cheapest-flights-within-k-stops
1448-count-good-nodes-in-binary-tree

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
0112-path-sum
0117-populating-next-right-pointers-in-each-node-ii
0127-word-ladder
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
0297-serialize-and-deserialize-binary-tree
0322-coin-change
0329-longest-increasing-path-in-a-matrix
0399-evaluate-division
0417-pacific-atlantic-water-flow
0433-minimum-genetic-mutation
0530-minimum-absolute-difference-in-bst
0637-average-of-levels-in-binary-tree
0684-redundant-connection
0695-max-area-of-island
0733-flood-fill
0744-network-delay-time
0794-swim-in-rising-water
0803-cheapest-flights-within-k-stops
0945-snakes-and-ladders
1036-rotting-oranges
1448-count-good-nodes-in-binary-tree
1757-minimum-jumps-to-reach-home

Binary Tree

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
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
0117-populating-next-right-pointers-in-each-node-ii
0124-binary-tree-maximum-path-sum
0129-sum-root-to-leaf-numbers
0173-binary-search-tree-iterator
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
0236-lowest-common-ancestor-of-a-binary-tree
0297-serialize-and-deserialize-binary-tree
0530-minimum-absolute-difference-in-bst
0543-diameter-of-binary-tree
0572-subtree-of-another-tree
0637-average-of-levels-in-binary-tree
0703-kth-largest-element-in-a-stream
1448-count-good-nodes-in-binary-tree

Linked List

0002-add-two-numbers
0019-remove-nth-node-from-end-of-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
0086-partition-list
0092-reverse-linked-list-ii
0114-flatten-binary-tree-to-linked-list
0117-populating-next-right-pointers-in-each-node-ii
0138-copy-list-with-random-pointer
0141-linked-list-cycle
0143-reorder-list
0146-lru-cache
0148-sort-list
0206-reverse-linked-list
0355-design-twitter
0460-lfu-cache

Stack

0020-valid-parentheses
0042-trapping-rain-water
0071-simplify-path
0084-largest-rectangle-in-histogram
0114-flatten-binary-tree-to-linked-list
0143-reorder-list
0150-evaluate-reverse-polish-notation
0155-min-stack
0173-binary-search-tree-iterator
0224-basic-calculator
0678-valid-parenthesis-string
0739-daily-temperatures
0853-car-fleet
0895-maximum-frequency-stack

Design

0146-lru-cache
0155-min-stack
0173-binary-search-tree-iterator
0208-implement-trie-prefix-tree
0211-design-add-and-search-words-data-structure
0295-find-median-from-data-stream
0297-serialize-and-deserialize-binary-tree
0355-design-twitter
0380-insert-delete-getrandom-o1
0460-lfu-cache
0703-kth-largest-element-in-a-stream
0895-maximum-frequency-stack
0981-time-based-key-value-store

Binary Search Tree

0098-validate-binary-search-tree
0108-convert-sorted-array-to-binary-search-tree
0173-binary-search-tree-iterator
0230-kth-smallest-element-in-a-bst
0235-lowest-common-ancestor-of-a-binary-search-tree
0530-minimum-absolute-difference-in-bst
0703-kth-largest-element-in-a-stream

Iterator

0173-binary-search-tree-iterator

Backtracking

0017-letter-combinations-of-a-phone-number
0022-generate-parentheses
0039-combination-sum
0040-combination-sum-ii
0046-permutations
0051-n-queens
0077-combinations
0078-subsets
0079-word-search
0090-subsets-ii
0131-palindrome-partitioning
0212-word-search-ii
0494-target-sum

Heap (Priority Queue)

0023-merge-k-sorted-lists
0215-kth-largest-element-in-an-array
0239-sliding-window-maximum
0295-find-median-from-data-stream
0347-top-k-frequent-elements
0355-design-twitter
0373-find-k-pairs-with-smallest-sums
0502-ipo
0621-task-scheduler
0703-kth-largest-element-in-a-stream
0744-network-delay-time
0794-swim-in-rising-water
0803-cheapest-flights-within-k-stops
0973-k-closest-points-to-origin
1046-last-stone-weight
1851-minimum-interval-to-include-each-query

Quickselect

0215-kth-largest-element-in-an-array
0347-top-k-frequent-elements
0973-k-closest-points-to-origin

Merge Sort

0023-merge-k-sorted-lists
0148-sort-list

Math

0002-add-two-numbers
0009-palindrome-number
0012-integer-to-roman
0013-roman-to-integer
0048-rotate-image
0050-powx-n
0062-unique-paths
0066-plus-one
0067-add-binary
0069-sqrtx
0070-climbing-stairs
0149-max-points-on-a-line
0150-evaluate-reverse-polish-notation
0172-factorial-trailing-zeroes
0189-rotate-array
0202-happy-number
0224-basic-calculator
0380-insert-delete-getrandom-o1
0973-k-closest-points-to-origin

Memoization

0070-climbing-stairs
0139-word-break
0329-longest-increasing-path-in-a-matrix

Trie

0014-longest-common-prefix
0139-word-break
0208-implement-trie-prefix-tree
0211-design-add-and-search-words-data-structure
0212-word-search-ii

Recursion

0002-add-two-numbers
0010-regular-expression-matching
0021-merge-two-sorted-lists
0025-reverse-nodes-in-k-group
0050-powx-n
0143-reorder-list
0206-reverse-linked-list
0224-basic-calculator

Doubly-Linked List

0146-lru-cache
0460-lfu-cache

Union Find

0128-longest-consecutive-sequence
0130-surrounded-regions
0200-number-of-islands
0399-evaluate-division
0684-redundant-connection
0695-max-area-of-island
0794-swim-in-rising-water
1706-min-cost-to-connect-all-points

Simulation

0054-spiral-matrix
0067-add-binary
0068-text-justification
0289-game-of-life

Rolling Hash

0718-maximum-length-of-repeated-subarray

Hash Function

0572-subtree-of-another-tree
0718-maximum-length-of-repeated-subarray

Counting Sort

0274-h-index

Randomized

0380-insert-delete-getrandom-o1

String Matching

0028-find-the-index-of-the-first-occurrence-in-a-string
0572-subtree-of-another-tree

Graph

0133-clone-graph
0207-course-schedule
0210-course-schedule-ii
0329-longest-increasing-path-in-a-matrix
0332-reconstruct-itinerary
0399-evaluate-division
0684-redundant-connection
0744-network-delay-time
0803-cheapest-flights-within-k-stops
1706-min-cost-to-connect-all-points

Shortest Path

0399-evaluate-division
0744-network-delay-time
0803-cheapest-flights-within-k-stops

Topological Sort

0207-course-schedule
0210-course-schedule-ii
0329-longest-increasing-path-in-a-matrix

Bit Manipulation

0067-add-binary
0078-subsets
0090-subsets-ii
0136-single-number
0137-single-number-ii
0190-reverse-bits
0191-number-of-1-bits
0222-count-complete-tree-nodes
0287-find-the-duplicate-number

Database

0175-combine-two-tables
0181-employees-earning-more-than-their-managers
0182-duplicate-emails

Monotonic Stack

0042-trapping-rain-water
0084-largest-rectangle-in-histogram
0739-daily-temperatures
0853-car-fleet

Data Stream

0295-find-median-from-data-stream
0703-kth-largest-element-in-a-stream

Geometry

0149-max-points-on-a-line
0973-k-closest-points-to-origin

Eulerian Circuit

0332-reconstruct-itinerary

Minimum Spanning Tree

1706-min-cost-to-connect-all-points

Combinatorics

0062-unique-paths

Line Sweep

1851-minimum-interval-to-include-each-query

Bucket Sort

0347-top-k-frequent-elements

Ordered Set

0895-maximum-frequency-stack