Leetcode

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

Array

0330-patching-array
0502-ipo

Greedy

0330-patching-array
0502-ipo

Sorting

0502-ipo

Heap (Priority Queue)

0023-merge-k-sorted-lists
0502-ipo

Linked List

0002-add-two-numbers
0019-remove-nth-node-from-end-of-list
0021-merge-two-sorted-lists
0023-merge-k-sorted-lists
0024-swap-nodes-in-pairs
0061-rotate-list
0082-remove-duplicates-from-sorted-list-ii
0083-remove-duplicates-from-sorted-list

Math

0002-add-two-numbers

Recursion

0002-add-two-numbers
0021-merge-two-sorted-lists
0024-swap-nodes-in-pairs

Two Pointers

0019-remove-nth-node-from-end-of-list
0061-rotate-list
0082-remove-duplicates-from-sorted-list-ii

Divide and Conquer

0023-merge-k-sorted-lists

Merge Sort

0023-merge-k-sorted-lists

LeetCode Topics

Array

0016-3sum-closest
0118-pascals-triangle
0130-surrounded-regions
0136-single-number
0200-number-of-islands
0209-minimum-size-subarray-sum
0215-kth-largest-element-in-an-array
0217-contains-duplicate
0221-maximal-square
0268-missing-number
0307-range-sum-query-mutable
0373-find-k-pairs-with-smallest-sums
0378-kth-smallest-element-in-a-sorted-matrix
0393-utf-8-validation
0448-find-all-numbers-disappeared-in-an-array
0475-heaters
0494-target-sum
0503-next-greater-element-ii
0542-01-matrix
0594-longest-harmonious-subsequence
0643-maximum-average-subarray-i
0733-flood-fill
0816-design-hashset
0859-design-circular-deque
0860-design-circular-queue
0901-advantage-shuffle
0934-bitwise-ors-of-subarrays
0940-fruit-into-baskets
0952-word-subsets
0976-minimum-area-rectangle
1025-minimum-cost-for-tickets
1036-rotting-oranges
1063-best-sightseeing-pair
1073-number-of-enclaves
1207-delete-nodes-and-return-forest
1227-number-of-equivalent-domino-pairs
1293-three-consecutive-odds
1333-sort-the-jumbled-numbers
1335-maximum-candies-allocated-to-k-children
1350-remove-sub-folders-from-the-filesystem
1478-maximum-number-of-events-that-can-be-attended
1485-minimum-cost-to-make-at-least-one-valid-path-in-a-grid
1496-lucky-numbers-in-a-matrix
1524-string-matching-in-an-array
1538-maximum-points-you-can-obtain-from-cards
1549-longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit
1556-make-two-arrays-equal-by-reversing-subarrays
1616-minimum-difference-between-largest-and-smallest-value-in-three-moves
1656-count-good-triplets
1663-detect-cycles-in-2d-grid
1679-shortest-subarray-to-be-removed-to-make-array-sorted
1711-find-valid-matrix-given-row-and-column-sums
1720-crawler-log-folder
1741-sort-array-by-increasing-frequency
1755-defuse-the-bomb
1813-maximum-erasure-value
1849-maximum-absolute-sum-of-any-subarray
1876-map-of-highest-peak
1886-minimum-limit-of-balls-in-a-bag
1895-minimum-number-of-operations-to-move-all-balls-to-each-box
1951-find-the-winner-of-the-circular-game
1972-rotating-the-box
1975-minimum-distance-to-the-target-element
1993-sum-of-all-subset-xor-totals
1995-finding-pairs-with-a-certain-sum
2022-maximum-alternating-subsequence-sum
2089-maximum-matrix-sum
2103-find-all-groups-of-farmland
2144-maximum-difference-between-increasing-elements
2145-grid-game
2160-minimum-operations-to-make-a-uni-value-grid
2163-kth-distinct-string-in-an-array
2188-minimized-maximum-of-products-distributed-to-any-store
2232-adding-spaces-to-a-string
2237-longest-palindrome-by-concatenating-two-letter-words
2262-solving-questions-with-brainpower
2265-partition-array-according-to-given-pivot
2292-counting-words-with-a-given-prefix
2306-create-binary-tree-from-descriptions
2308-divide-array-into-equal-pairs
2316-count-hills-and-valleys-in-an-array
2320-find-all-k-distant-indices-in-an-array
2338-minimum-consecutive-cards-to-pick-up
2358-number-of-ways-to-split-array
2374-steps-to-make-array-non-decreasing
2411-spiral-matrix-iv
2421-maximum-number-of-pairs-in-array
2472-build-a-matrix-with-conditions
2473-max-sum-of-a-pair-with-equal-sum-of-digits
2476-check-distances-between-same-letters
2478-longest-nice-subarray
2497-maximum-matching-of-players-with-trainers
2498-smallest-subarrays-with-maximum-bitwise-or
2502-sort-the-people
2503-longest-subarray-with-maximum-bitwise-and
2533-bitwise-xor-of-all-pairings
2551-apply-operations-to-an-array
2552-maximum-sum-of-distinct-subarrays-with-length-k
2585-delete-greatest-value-in-each-row
2631-sort-the-students-by-their-kth-score
2665-minimum-time-to-repair-cars
2685-first-completely-painted-row-or-column
2691-count-vowel-strings-in-ranges
2707-merge-two-2d-arrays-by-summing-values
2766-find-the-prefix-common-array-of-two-arrays
2792-neighboring-bitwise-xor
2856-count-complete-subarrays-in-an-array
2868-continuous-subarrays
2888-minimum-index-of-a-valid-split
2915-count-of-interesting-subarrays
3080-split-array-into-maximum-number-of-subarrays
3143-longest-unequal-adjacent-groups-subsequence-i
3154-maximum-value-of-an-ordered-triplet-i
3165-find-indices-with-index-and-value-difference-i
3170-find-indices-with-index-and-value-difference-ii
3171-minimum-equal-sum-of-two-arrays-after-replacing-zeros
3176-minimum-sum-of-mountain-triplets-i
3186-minimum-sum-of-mountain-triplets-ii
3193-maximum-strong-pair-xor-i
3194-find-words-containing-character
3227-find-missing-and-repeated-values
3269-number-of-subarrays-that-match-a-pattern-i
3309-count-prefix-and-suffix-pairs-i
3321-type-of-triangle
3335-minimum-operations-to-write-the-letter-y-on-a-grid
3463-alternating-groups-i
3475-minimum-operations-to-make-binary-array-elements-equal-to-one-i
3483-alternating-groups-ii
3490-find-the-maximum-length-of-valid-subsequence-i
3621-minimum-operations-to-make-array-values-equal-to-k
3639-zero-array-transformation-i
3656-minimum-number-of-operations-to-make-elements-in-array-distinct
3788-maximum-unique-subarray-sum-after-deletion
3790-fruits-into-baskets-ii
3809-properties-graph
3909-minimum-increments-to-equalize-leaf-paths

Math

0002-add-two-numbers
0050-powx-n
0268-missing-number
0371-sum-of-two-integers
0382-linked-list-random-node
0445-add-two-numbers-ii
0755-reach-a-number
0976-minimum-area-rectangle
1236-n-th-tribonacci-number
1307-ugly-number-iii
1411-convert-binary-number-in-a-linked-list-to-integer
1500-count-largest-group
1515-find-the-minimum-number-of-fibonacci-numbers-whose-sum-is-k
1885-count-number-of-homogenous-substrings
1889-check-if-number-is-a-sum-of-powers-of-three
1951-find-the-winner-of-the-circular-game
1993-sum-of-all-subset-xor-totals
2160-minimum-operations-to-make-a-uni-value-grid
2610-closest-prime-numbers-in-range
2630-alternating-digit-sum
2649-count-total-number-of-colored-cells
2650-split-with-minimum-sum
2871-double-a-number-represented-as-a-linked-list
3227-find-missing-and-repeated-values
3275-minimum-number-of-pushes-to-type-word-i
3321-type-of-triangle

Recursion

0002-add-two-numbers
0021-merge-two-sorted-lists
0024-swap-nodes-in-pairs
0050-powx-n
0143-reorder-list
0203-remove-linked-list-elements
0206-reverse-linked-list
0234-palindrome-linked-list
1951-find-the-winner-of-the-circular-game
2573-remove-nodes-from-linked-list

Queue

0225-implement-stack-using-queues
0387-first-unique-character-in-a-string
0859-design-circular-deque
0860-design-circular-queue
0969-number-of-recent-calls
1549-longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit
1951-find-the-winner-of-the-circular-game
2868-continuous-subarrays
3475-minimum-operations-to-make-binary-array-elements-equal-to-one-i

Simulation

1951-find-the-winner-of-the-circular-game
2232-adding-spaces-to-a-string
2265-partition-array-according-to-given-pivot
2299-merge-nodes-in-between-zeros
2411-spiral-matrix-iv
2551-apply-operations-to-an-array
2585-delete-greatest-value-in-each-row
3790-fruits-into-baskets-ii

String

0003-longest-substring-without-repeating-characters
0127-word-ladder
0387-first-unique-character-in-a-string
0424-longest-repeating-character-replacement
0438-find-all-anagrams-in-a-string
0567-permutation-in-string
0778-reorganize-string
0812-rotate-string
0952-word-subsets
1298-reverse-substrings-between-each-pair-of-parentheses
1302-delete-characters-to-make-fancy-string
1350-remove-sub-folders-from-the-filesystem
1502-construct-k-palindrome-strings
1520-number-of-steps-to-reduce-a-number-in-binary-representation-to-one
1524-string-matching-in-an-array
1537-maximum-score-after-splitting-a-string
1557-check-if-a-string-contains-all-binary-codes-of-size-k
1567-maximum-number-of-vowels-in-a-substring-of-given-length
1720-crawler-log-folder
1818-maximum-score-from-removing-substrings
1885-count-number-of-homogenous-substrings
1890-sum-of-beauty-of-all-substrings
1895-minimum-number-of-operations-to-move-all-balls-to-each-box
2163-kth-distinct-string-in-an-array
2217-step-by-step-directions-from-a-binary-tree-node-to-another
2221-check-if-a-parentheses-string-can-be-valid
2232-adding-spaces-to-a-string
2237-longest-palindrome-by-concatenating-two-letter-words
2292-counting-words-with-a-given-prefix
2395-longest-binary-subsequence-less-than-or-equal-to-k
2456-construct-smallest-number-from-di-string
2476-check-distances-between-same-letters
2502-sort-the-people
2691-count-vowel-strings-in-ranges
3018-make-string-a-subsequence-using-cyclic-increments
3143-longest-unequal-adjacent-groups-subsequence-i
3194-find-words-containing-character
3275-minimum-number-of-pushes-to-type-word-i
3276-minimum-number-of-pushes-to-type-word-ii
3309-count-prefix-and-suffix-pairs-i
3396-valid-word
3405-count-the-number-of-special-characters-ii
3408-count-the-number-of-special-characters-i
3455-minimum-length-of-string-after-operations
3569-count-of-substrings-containing-every-vowel-and-k-consonants-ii
3617-find-the-original-typed-string-i

Tree

0094-binary-tree-inorder-traversal
0095-unique-binary-search-trees-ii
0098-validate-binary-search-tree
0100-same-tree
0102-binary-tree-level-order-traversal
0104-maximum-depth-of-binary-tree
0109-convert-sorted-list-to-binary-search-tree
0112-path-sum
0114-flatten-binary-tree-to-linked-list
0116-populating-next-right-pointers-in-each-node
0117-populating-next-right-pointers-in-each-node-ii
0124-binary-tree-maximum-path-sum
0226-invert-binary-tree
0230-kth-smallest-element-in-a-bst
0235-lowest-common-ancestor-of-a-binary-search-tree
0515-find-largest-value-in-each-tree-row
0530-minimum-absolute-difference-in-bst
0572-subtree-of-another-tree
0789-kth-largest-element-in-a-stream
1207-delete-nodes-and-return-forest
1218-lowest-common-ancestor-of-deepest-leaves
1484-linked-list-in-binary-tree
1653-number-of-good-leaf-nodes-pairs
2217-step-by-step-directions-from-a-binary-tree-node-to-another
2306-create-binary-tree-from-descriptions
2493-reverse-odd-levels-of-binary-tree
2558-minimum-number-of-operations-to-sort-a-binary-tree-by-level
3909-minimum-increments-to-equalize-leaf-paths

Depth-First Search

0094-binary-tree-inorder-traversal
0098-validate-binary-search-tree
0100-same-tree
0104-maximum-depth-of-binary-tree
0112-path-sum
0114-flatten-binary-tree-to-linked-list
0116-populating-next-right-pointers-in-each-node
0117-populating-next-right-pointers-in-each-node-ii
0124-binary-tree-maximum-path-sum
0130-surrounded-regions
0200-number-of-islands
0207-course-schedule
0210-course-schedule-ii
0226-invert-binary-tree
0230-kth-smallest-element-in-a-bst
0235-lowest-common-ancestor-of-a-binary-search-tree
0515-find-largest-value-in-each-tree-row
0530-minimum-absolute-difference-in-bst
0572-subtree-of-another-tree
0733-flood-fill
0801-is-graph-bipartite
0820-find-eventual-safe-states
1073-number-of-enclaves
1207-delete-nodes-and-return-forest
1218-lowest-common-ancestor-of-deepest-leaves
1350-remove-sub-folders-from-the-filesystem
1484-linked-list-in-binary-tree
1653-number-of-good-leaf-nodes-pairs
1663-detect-cycles-in-2d-grid
2103-find-all-groups-of-farmland
2217-step-by-step-directions-from-a-binary-tree-node-to-another
2438-find-closest-node-to-given-two-nodes
2439-longest-cycle-in-a-graph
2493-reverse-odd-levels-of-binary-tree
2793-count-the-number-of-complete-components
3809-properties-graph
3909-minimum-increments-to-equalize-leaf-paths

Binary Tree

0094-binary-tree-inorder-traversal
0095-unique-binary-search-trees-ii
0098-validate-binary-search-tree
0100-same-tree
0102-binary-tree-level-order-traversal
0104-maximum-depth-of-binary-tree
0109-convert-sorted-list-to-binary-search-tree
0112-path-sum
0114-flatten-binary-tree-to-linked-list
0116-populating-next-right-pointers-in-each-node
0117-populating-next-right-pointers-in-each-node-ii
0124-binary-tree-maximum-path-sum
0226-invert-binary-tree
0230-kth-smallest-element-in-a-bst
0235-lowest-common-ancestor-of-a-binary-search-tree
0515-find-largest-value-in-each-tree-row
0530-minimum-absolute-difference-in-bst
0572-subtree-of-another-tree
0789-kth-largest-element-in-a-stream
1207-delete-nodes-and-return-forest
1218-lowest-common-ancestor-of-deepest-leaves
1484-linked-list-in-binary-tree
1653-number-of-good-leaf-nodes-pairs
2217-step-by-step-directions-from-a-binary-tree-node-to-another
2306-create-binary-tree-from-descriptions
2493-reverse-odd-levels-of-binary-tree
2558-minimum-number-of-operations-to-sort-a-binary-tree-by-level

Greedy

0778-reorganize-string
0901-advantage-shuffle
1478-maximum-number-of-events-that-can-be-attended
1502-construct-k-palindrome-strings
1515-find-the-minimum-number-of-fibonacci-numbers-whose-sum-is-k
1616-minimum-difference-between-largest-and-smallest-value-in-three-moves
1711-find-valid-matrix-given-row-and-column-sums
1818-maximum-score-from-removing-substrings
2089-maximum-matrix-sum
2188-minimized-maximum-of-products-distributed-to-any-store
2221-check-if-a-parentheses-string-can-be-valid
2237-longest-palindrome-by-concatenating-two-letter-words
2395-longest-binary-subsequence-less-than-or-equal-to-k
2456-construct-smallest-number-from-di-string
2497-maximum-matching-of-players-with-trainers
2509-minimize-xor
2650-split-with-minimum-sum
3080-split-array-into-maximum-number-of-subarrays
3143-longest-unequal-adjacent-groups-subsequence-i
3171-minimum-equal-sum-of-two-arrays-after-replacing-zeros
3275-minimum-number-of-pushes-to-type-word-i
3276-minimum-number-of-pushes-to-type-word-ii
3788-maximum-unique-subarray-sum-after-deletion

Sorting

0016-3sum-closest
0215-kth-largest-element-in-an-array
0217-contains-duplicate
0268-missing-number
0295-find-median-from-data-stream
0378-kth-smallest-element-in-a-sorted-matrix
0475-heaters
0594-longest-harmonious-subsequence
0778-reorganize-string
0901-advantage-shuffle
0976-minimum-area-rectangle
1333-sort-the-jumbled-numbers
1478-maximum-number-of-events-that-can-be-attended
1556-make-two-arrays-equal-by-reversing-subarrays
1616-minimum-difference-between-largest-and-smallest-value-in-three-moves
1741-sort-array-by-increasing-frequency
2160-minimum-operations-to-make-a-uni-value-grid
2473-max-sum-of-a-pair-with-equal-sum-of-digits
2497-maximum-matching-of-players-with-trainers
2502-sort-the-people
2585-delete-greatest-value-in-each-row
2631-sort-the-students-by-their-kth-score
2650-split-with-minimum-sum
2888-minimum-index-of-a-valid-split
3276-minimum-number-of-pushes-to-type-word-ii
3321-type-of-triangle

Hash Table

0003-longest-substring-without-repeating-characters
0127-word-ladder
0138-copy-list-with-random-pointer
0141-linked-list-cycle
0142-linked-list-cycle-ii
0160-intersection-of-two-linked-lists
0217-contains-duplicate
0268-missing-number
0387-first-unique-character-in-a-string
0424-longest-repeating-character-replacement
0438-find-all-anagrams-in-a-string
0448-find-all-numbers-disappeared-in-an-array
0567-permutation-in-string
0594-longest-harmonious-subsequence
0778-reorganize-string
0816-design-hashset
0931-maximum-frequency-stack
0940-fruit-into-baskets
0952-word-subsets
0976-minimum-area-rectangle
1207-delete-nodes-and-return-forest
1218-lowest-common-ancestor-of-deepest-leaves
1227-number-of-equivalent-domino-pairs
1267-remove-zero-sum-consecutive-nodes-from-linked-list
1500-count-largest-group
1502-construct-k-palindrome-strings
1556-make-two-arrays-equal-by-reversing-subarrays
1557-check-if-a-string-contains-all-binary-codes-of-size-k
1741-sort-array-by-increasing-frequency
1813-maximum-erasure-value
1890-sum-of-beauty-of-all-substrings
1995-finding-pairs-with-a-certain-sum
2163-kth-distinct-string-in-an-array
2237-longest-palindrome-by-concatenating-two-letter-words
2306-create-binary-tree-from-descriptions
2308-divide-array-into-equal-pairs
2338-minimum-consecutive-cards-to-pick-up
2421-maximum-number-of-pairs-in-array
2473-max-sum-of-a-pair-with-equal-sum-of-digits
2476-check-distances-between-same-letters
2502-sort-the-people
2552-maximum-sum-of-distinct-subarrays-with-length-k
2685-first-completely-painted-row-or-column
2707-merge-two-2d-arrays-by-summing-values
2766-find-the-prefix-common-array-of-two-arrays
2856-count-complete-subarrays-in-an-array
2888-minimum-index-of-a-valid-split
2915-count-of-interesting-subarrays
3193-maximum-strong-pair-xor-i
3227-find-missing-and-repeated-values
3276-minimum-number-of-pushes-to-type-word-ii
3335-minimum-operations-to-write-the-letter-y-on-a-grid
3405-count-the-number-of-special-characters-ii
3408-count-the-number-of-special-characters-i
3455-minimum-length-of-string-after-operations
3569-count-of-substrings-containing-every-vowel-and-k-consonants-ii
3621-minimum-operations-to-make-array-values-equal-to-k
3656-minimum-number-of-operations-to-make-elements-in-array-distinct
3788-maximum-unique-subarray-sum-after-deletion
3809-properties-graph

Dynamic Programming

0095-unique-binary-search-trees-ii
0118-pascals-triangle
0124-binary-tree-maximum-path-sum
0221-maximal-square
0338-counting-bits
0494-target-sum
0542-01-matrix
0806-domino-and-tromino-tiling
0934-bitwise-ors-of-subarrays
1025-minimum-cost-for-tickets
1063-best-sightseeing-pair
1236-n-th-tribonacci-number
1849-maximum-absolute-sum-of-any-subarray
2022-maximum-alternating-subsequence-sum
2262-solving-questions-with-brainpower
2395-longest-binary-subsequence-less-than-or-equal-to-k
3143-longest-unequal-adjacent-groups-subsequence-i
3490-find-the-maximum-length-of-valid-subsequence-i
3909-minimum-increments-to-equalize-leaf-paths

Matrix

0130-surrounded-regions
0200-number-of-islands
0221-maximal-square
0378-kth-smallest-element-in-a-sorted-matrix
0542-01-matrix
0733-flood-fill
1036-rotting-oranges
1073-number-of-enclaves
1485-minimum-cost-to-make-at-least-one-valid-path-in-a-grid
1496-lucky-numbers-in-a-matrix
1663-detect-cycles-in-2d-grid
1711-find-valid-matrix-given-row-and-column-sums
1876-map-of-highest-peak
1972-rotating-the-box
2089-maximum-matrix-sum
2103-find-all-groups-of-farmland
2145-grid-game
2160-minimum-operations-to-make-a-uni-value-grid
2411-spiral-matrix-iv
2472-build-a-matrix-with-conditions
2585-delete-greatest-value-in-each-row
2631-sort-the-students-by-their-kth-score
2685-first-completely-painted-row-or-column
3227-find-missing-and-repeated-values
3335-minimum-operations-to-write-the-letter-y-on-a-grid

Graph

0207-course-schedule
0210-course-schedule-ii
0801-is-graph-bipartite
0820-find-eventual-safe-states
1485-minimum-cost-to-make-at-least-one-valid-path-in-a-grid
2438-find-closest-node-to-given-two-nodes
2439-longest-cycle-in-a-graph
2472-build-a-matrix-with-conditions
2793-count-the-number-of-complete-components
3809-properties-graph

Topological Sort

0207-course-schedule
0210-course-schedule-ii
0820-find-eventual-safe-states
2439-longest-cycle-in-a-graph
2472-build-a-matrix-with-conditions

Stack

0094-binary-tree-inorder-traversal
0114-flatten-binary-tree-to-linked-list
0143-reorder-list
0225-implement-stack-using-queues
0234-palindrome-linked-list
0445-add-two-numbers-ii
0503-next-greater-element-ii
0931-maximum-frequency-stack
1298-reverse-substrings-between-each-pair-of-parentheses
1679-shortest-subarray-to-be-removed-to-make-array-sorted
1720-crawler-log-folder
1818-maximum-score-from-removing-substrings
2221-check-if-a-parentheses-string-can-be-valid
2236-maximum-twin-sum-of-a-linked-list
2374-steps-to-make-array-non-decreasing
2456-construct-smallest-number-from-di-string
2573-remove-nodes-from-linked-list
2871-double-a-number-represented-as-a-linked-list

Binary Search

0209-minimum-size-subarray-sum
0268-missing-number
0378-kth-smallest-element-in-a-sorted-matrix
0475-heaters
0755-reach-a-number
1307-ugly-number-iii
1335-maximum-candies-allocated-to-k-children
1679-shortest-subarray-to-be-removed-to-make-array-sorted
1886-minimum-limit-of-balls-in-a-bag
2188-minimized-maximum-of-products-distributed-to-any-store
2498-smallest-subarrays-with-maximum-bitwise-or
2665-minimum-time-to-repair-cars
3790-fruits-into-baskets-ii

Combinatorics

1307-ugly-number-iii
1993-sum-of-all-subset-xor-totals

Number Theory

1307-ugly-number-iii
2610-closest-prime-numbers-in-range

Counting

0387-first-unique-character-in-a-string
0594-longest-harmonious-subsequence
0778-reorganize-string
1227-number-of-equivalent-domino-pairs
1502-construct-k-palindrome-strings
1890-sum-of-beauty-of-all-substrings
2163-kth-distinct-string-in-an-array
2237-longest-palindrome-by-concatenating-two-letter-words
2308-divide-array-into-equal-pairs
2421-maximum-number-of-pairs-in-array
3276-minimum-number-of-pushes-to-type-word-ii
3335-minimum-operations-to-write-the-letter-y-on-a-grid
3455-minimum-length-of-string-after-operations

Two Pointers

0016-3sum-closest
0019-remove-nth-node-from-end-of-list
0061-rotate-list
0082-remove-duplicates-from-sorted-list-ii
0086-partition-list
0141-linked-list-cycle
0142-linked-list-cycle-ii
0143-reorder-list
0160-intersection-of-two-linked-lists
0234-palindrome-linked-list
0295-find-median-from-data-stream
0475-heaters
0567-permutation-in-string
0901-advantage-shuffle
0908-middle-of-the-linked-list
1679-shortest-subarray-to-be-removed-to-make-array-sorted
1972-rotating-the-box
2216-delete-the-middle-node-of-a-linked-list
2232-adding-spaces-to-a-string
2236-maximum-twin-sum-of-a-linked-list
2265-partition-array-according-to-given-pivot
2320-find-all-k-distant-indices-in-an-array
2497-maximum-matching-of-players-with-trainers
2551-apply-operations-to-an-array
2707-merge-two-2d-arrays-by-summing-values
3018-make-string-a-subsequence-using-cyclic-increments
3165-find-indices-with-index-and-value-difference-i
3170-find-indices-with-index-and-value-difference-ii

Rolling Hash

1557-check-if-a-string-contains-all-binary-codes-of-size-k
3269-number-of-subarrays-that-match-a-pattern-i
3309-count-prefix-and-suffix-pairs-i

String Matching

0572-subtree-of-another-tree
0812-rotate-string
1524-string-matching-in-an-array
2292-counting-words-with-a-given-prefix
3269-number-of-subarrays-that-match-a-pattern-i
3309-count-prefix-and-suffix-pairs-i

Hash Function

0572-subtree-of-another-tree
0816-design-hashset
1557-check-if-a-string-contains-all-binary-codes-of-size-k
3269-number-of-subarrays-that-match-a-pattern-i
3309-count-prefix-and-suffix-pairs-i

Design

0225-implement-stack-using-queues
0295-find-median-from-data-stream
0307-range-sum-query-mutable
0789-kth-largest-element-in-a-stream
0816-design-hashset
0859-design-circular-deque
0860-design-circular-queue
0931-maximum-frequency-stack
0969-number-of-recent-calls
1955-seat-reservation-manager
1995-finding-pairs-with-a-certain-sum

Breadth-First Search

0100-same-tree
0102-binary-tree-level-order-traversal
0104-maximum-depth-of-binary-tree
0112-path-sum
0116-populating-next-right-pointers-in-each-node
0117-populating-next-right-pointers-in-each-node-ii
0127-word-ladder
0130-surrounded-regions
0200-number-of-islands
0207-course-schedule
0210-course-schedule-ii
0226-invert-binary-tree
0515-find-largest-value-in-each-tree-row
0530-minimum-absolute-difference-in-bst
0542-01-matrix
0733-flood-fill
0801-is-graph-bipartite
0820-find-eventual-safe-states
1036-rotting-oranges
1073-number-of-enclaves
1218-lowest-common-ancestor-of-deepest-leaves
1485-minimum-cost-to-make-at-least-one-valid-path-in-a-grid
1663-detect-cycles-in-2d-grid
1876-map-of-highest-peak
2103-find-all-groups-of-farmland
2439-longest-cycle-in-a-graph
2493-reverse-odd-levels-of-binary-tree
2558-minimum-number-of-operations-to-sort-a-binary-tree-by-level
2793-count-the-number-of-complete-components
3809-properties-graph

Binary Search Tree

0095-unique-binary-search-trees-ii
0098-validate-binary-search-tree
0109-convert-sorted-list-to-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

Heap (Priority Queue)

0023-merge-k-sorted-lists
0215-kth-largest-element-in-an-array
0295-find-median-from-data-stream
0373-find-k-pairs-with-smallest-sums
0378-kth-smallest-element-in-a-sorted-matrix
0778-reorganize-string
0789-kth-largest-element-in-a-stream
1478-maximum-number-of-events-that-can-be-attended
1485-minimum-cost-to-make-at-least-one-valid-path-in-a-grid
1549-longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit
1955-seat-reservation-manager
2473-max-sum-of-a-pair-with-equal-sum-of-digits
2585-delete-greatest-value-in-each-row
2868-continuous-subarrays

Data Stream

0295-find-median-from-data-stream
0789-kth-largest-element-in-a-stream
0969-number-of-recent-calls

Database

0596-classes-more-than-5-students
1179-game-play-analysis-i

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
1538-maximum-points-you-can-obtain-from-cards
1549-longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit
1567-maximum-number-of-vowels-in-a-substring-of-given-length
1755-defuse-the-bomb
1813-maximum-erasure-value
2338-minimum-consecutive-cards-to-pick-up
2478-longest-nice-subarray
2498-smallest-subarrays-with-maximum-bitwise-or
2552-maximum-sum-of-distinct-subarrays-with-length-k
2856-count-complete-subarrays-in-an-array
2868-continuous-subarrays
3193-maximum-strong-pair-xor-i
3463-alternating-groups-i
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

Prefix Sum

0209-minimum-size-subarray-sum
1537-maximum-score-after-splitting-a-string
1538-maximum-points-you-can-obtain-from-cards
1895-minimum-number-of-operations-to-move-all-balls-to-each-box
2145-grid-game
2358-number-of-ways-to-split-array
2691-count-vowel-strings-in-ranges
2915-count-of-interesting-subarrays
3475-minimum-operations-to-make-binary-array-elements-equal-to-one-i
3639-zero-array-transformation-i

Ordered Set

0931-maximum-frequency-stack
1549-longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit
2868-continuous-subarrays
3790-fruits-into-baskets-ii

Monotonic Queue

1549-longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit
2868-continuous-subarrays

Monotonic Stack

0503-next-greater-element-ii
1679-shortest-subarray-to-be-removed-to-make-array-sorted
2374-steps-to-make-array-non-decreasing
2573-remove-nodes-from-linked-list

Backtracking

0095-unique-binary-search-trees-ii
0494-target-sum
1993-sum-of-all-subset-xor-totals
2456-construct-smallest-number-from-di-string

Bit Manipulation

0136-single-number
0190-reverse-bits
0191-number-of-1-bits
0268-missing-number
0338-counting-bits
0371-sum-of-two-integers
0393-utf-8-validation
0934-bitwise-ors-of-subarrays
1520-number-of-steps-to-reduce-a-number-in-binary-representation-to-one
1557-check-if-a-string-contains-all-binary-codes-of-size-k
1993-sum-of-all-subset-xor-totals
2308-divide-array-into-equal-pairs
2478-longest-nice-subarray
2498-smallest-subarrays-with-maximum-bitwise-or
2503-longest-subarray-with-maximum-bitwise-and
2509-minimize-xor
2533-bitwise-xor-of-all-pairings
2766-find-the-prefix-common-array-of-two-arrays
2792-neighboring-bitwise-xor
3080-split-array-into-maximum-number-of-subarrays
3193-maximum-strong-pair-xor-i
3475-minimum-operations-to-make-binary-array-elements-equal-to-one-i

Divide and Conquer

0023-merge-k-sorted-lists
0109-convert-sorted-list-to-binary-search-tree
0190-reverse-bits
0191-number-of-1-bits
0215-kth-largest-element-in-an-array

Quickselect

0215-kth-largest-element-in-an-array

Linked List

0002-add-two-numbers
0019-remove-nth-node-from-end-of-list
0021-merge-two-sorted-lists
0023-merge-k-sorted-lists
0024-swap-nodes-in-pairs
0061-rotate-list
0082-remove-duplicates-from-sorted-list-ii
0083-remove-duplicates-from-sorted-list
0086-partition-list
0092-reverse-linked-list-ii
0109-convert-sorted-list-to-binary-search-tree
0114-flatten-binary-tree-to-linked-list
0116-populating-next-right-pointers-in-each-node
0117-populating-next-right-pointers-in-each-node-ii
0138-copy-list-with-random-pointer
0141-linked-list-cycle
0142-linked-list-cycle-ii
0143-reorder-list
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
0328-odd-even-linked-list
0382-linked-list-random-node
0445-add-two-numbers-ii
0725-split-linked-list-in-parts
0816-design-hashset
0859-design-circular-deque
0860-design-circular-queue
0908-middle-of-the-linked-list
1267-remove-zero-sum-consecutive-nodes-from-linked-list
1411-convert-binary-number-in-a-linked-list-to-integer
1484-linked-list-in-binary-tree
1765-merge-in-between-linked-lists
2196-reverse-nodes-in-even-length-groups
2216-delete-the-middle-node-of-a-linked-list
2236-maximum-twin-sum-of-a-linked-list
2299-merge-nodes-in-between-zeros
2374-steps-to-make-array-non-decreasing
2411-spiral-matrix-iv
2573-remove-nodes-from-linked-list
2871-double-a-number-represented-as-a-linked-list

Merge Sort

0023-merge-k-sorted-lists

Trie

1350-remove-sub-folders-from-the-filesystem
3193-maximum-strong-pair-xor-i
3309-count-prefix-and-suffix-pairs-i

Brainteaser

2503-longest-subarray-with-maximum-bitwise-and
2533-bitwise-xor-of-all-pairings

Shortest Path

1485-minimum-cost-to-make-at-least-one-valid-path-in-a-grid

Union Find

0130-surrounded-regions
0200-number-of-islands
0801-is-graph-bipartite
1073-number-of-enclaves
1663-detect-cycles-in-2d-grid
2793-count-the-number-of-complete-components
3809-properties-graph

Enumeration

1656-count-good-triplets
1993-sum-of-all-subset-xor-totals

Reservoir Sampling

0382-linked-list-random-node

Randomized

0382-linked-list-random-node

Memoization

1236-n-th-tribonacci-number
2395-longest-binary-subsequence-less-than-or-equal-to-k

Geometry

0976-minimum-area-rectangle

Segment Tree

0307-range-sum-query-mutable
3790-fruits-into-baskets-ii

Binary Indexed Tree

0307-range-sum-query-mutable