LeetCode

A collection of LeetCode questions to ace the coding interview! - Created using LeetHub v2

LeetCode Topics

Math

0002-add-two-numbers
0009-palindrome-number
0013-roman-to-integer
0062-unique-paths
0066-plus-one
0067-add-binary
0166-fraction-to-recurring-decimal
0202-happy-number
0762-prime-number-of-set-bits-in-binary-representation
0797-rabbits-in-forest
0830-largest-triangle-area
0840-magic-squares-in-grid
1015-smallest-integer-divisible-by-k
1018-largest-perimeter-triangle
1390-four-divisors
1421-find-numbers-with-even-number-of-digits
1426-find-n-unique-integers-sum-up-to-zero
1440-convert-integer-to-the-sum-of-two-no-zero-integers
1500-count-largest-group
1523-count-odd-numbers-in-an-interval-range
1524-number-of-sub-arrays-with-odd-sum
1585-the-kth-factor-of-n
1636-number-of-substrings-with-only-1s
1814-count-nice-pairs-in-an-array
1817-calculate-money-in-leetcode-bank
1925-count-square-sum-triples
1993-sum-of-all-subset-xor-totals
2050-count-good-numbers
2110-number-of-smooth-descent-periods-of-a-stock
2147-number-of-ways-to-divide-a-long-corridor
2160-minimum-operations-to-make-a-uni-value-grid
2174-next-greater-numerically-balanced-number
2244-number-of-laser-beams-in-a-bank
2307-replace-non-coprime-numbers-in-array
2324-find-triangular-sum-of-an-array
2432-number-of-zero-filled-subarrays
2507-number-of-common-factors
2661-smallest-missing-non-negative-integer-after-operations
2753-minimum-number-of-operations-to-make-all-array-elements-equal-to-1
2998-count-symmetric-integers
3273-most-expensive-item-that-can-not-be-bought
3277-find-the-number-of-ways-to-place-people-ii
3278-find-the-number-of-ways-to-place-people-i
3279-alice-and-bob-playing-flower-game
3336-water-bottles-ii
3432-count-partitions-with-even-sum-difference
3433-count-mentions-per-user
3462-vowels-game-in-a-string
3476-find-minimum-operations-to-make-all-elements-divisible-by-three
3577-count-the-number-of-computer-unlocking-permutations
3623-count-number-of-trapezoids-i
3676-smallest-number-with-all-set-bits
3744-minimum-operations-to-make-array-elements-zero
3768-check-if-digits-are-equal-in-string-after-operations-i
3830-find-closest-person

String

0003-longest-substring-without-repeating-characters
0005-longest-palindromic-substring
0006-zigzag-conversion
0013-roman-to-integer
0017-letter-combinations-of-a-phone-number
0020-valid-parentheses
0022-generate-parentheses
0028-find-the-index-of-the-first-occurrence-in-a-string
0038-count-and-say
0049-group-anagrams
0067-add-binary
0071-simplify-path
0072-edit-distance
0079-word-search
0097-interleaving-string
0125-valid-palindrome
0139-word-break
0151-reverse-words-in-a-string
0165-compare-version-numbers
0166-fraction-to-recurring-decimal
0205-isomorphic-strings
0208-implement-trie-prefix-tree
0266-palindrome-permutation
0424-longest-repeating-character-replacement
0474-ones-and-zeroes
0712-minimum-ascii-delete-sum-for-two-strings
0756-pyramid-transition-matrix
0761-special-binary-string
0768-partition-labels
0944-delete-columns-to-make-sorted
0955-delete-columns-to-make-sorted-ii
0960-delete-columns-to-make-sorted-iii
1006-vowel-spellchecker
1030-smallest-string-starting-from-leaf
1051-shortest-way-to-form-string
1081-smallest-subsequence-of-distinct-characters
1084-find-k-length-substrings-with-no-repeated-characters
1093-recover-a-tree-from-preorder-traversal
1108-analyze-user-website-visit-pattern
1250-longest-common-subsequence
1264-maximum-number-of-words-you-can-type
1302-delete-characters-to-make-fancy-string
1353-find-resultant-array-after-removing-anagrams
1419-minimum-number-of-frogs-croaking
1636-number-of-substrings-with-only-1s
1653-minimum-deletions-to-make-string-balanced
1700-minimum-time-to-make-rope-colorful
1747-lexicographically-smallest-string-after-applying-operations
1769-minimum-number-of-operations-to-move-all-balls-to-each-box
1960-check-if-the-sentence-is-pangram
2053-check-if-all-characters-have-equal-number-of-occurrences
2059-unique-length-3-palindromic-subsequences
2096-step-by-step-directions-from-a-binary-tree-node-to-another
2147-number-of-ways-to-divide-a-long-corridor
2211-count-collisions-on-a-road
2220-find-all-possible-recipes-from-given-supplies
2244-number-of-laser-beams-in-a-bank
2345-minimum-number-of-operations-to-convert-time
2427-first-letter-to-appear-twice
2429-design-a-food-rating-system
2483-minimum-penalty-for-a-shop
2887-sort-vowels-in-a-string
2976-minimum-cost-to-convert-string-i
3121-count-the-number-of-special-characters-ii
3462-vowels-game-in-a-string
3479-count-the-number-of-substrings-with-dominant-ones
3493-maximum-number-of-operations-to-move-ones-to-the-end
3543-count-substrings-that-satisfy-k-constraint-i
3606-coupon-code-validator
3713-longest-balanced-substring-i
3714-longest-balanced-substring-ii
3768-check-if-digits-are-equal-in-string-after-operations-i
3797-design-spreadsheet
3872-find-most-frequent-vowel-and-consonant

Stack

0020-valid-parentheses
0042-trapping-rain-water
0071-simplify-path
0114-flatten-binary-tree-to-linked-list
0496-next-greater-element-i
0739-daily-temperatures
0853-car-fleet
0901-online-stock-span
0943-sum-of-subarray-minimums
1008-construct-binary-search-tree-from-preorder-traversal
1019-next-greater-node-in-linked-list
1081-smallest-subsequence-of-distinct-characters
1472-design-browser-history
1633-minimum-number-of-increments-on-subarrays-to-form-a-target-array
1653-minimum-deletions-to-make-string-balanced
2211-count-collisions-on-a-road
2307-replace-non-coprime-numbers-in-array
2487-remove-nodes-from-linked-list

Array

0001-two-sum
0004-median-of-two-sorted-arrays
0011-container-with-most-water
0015-3sum
0016-3sum-closest
0018-4sum
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
0049-group-anagrams
0051-n-queens
0053-maximum-subarray
0057-insert-interval
0063-unique-paths-ii
0064-minimum-path-sum
0066-plus-one
0074-search-a-2d-matrix
0075-sort-colors
0078-subsets
0079-word-search
0081-search-in-rotated-sorted-array-ii
0106-construct-binary-tree-from-inorder-and-postorder-traversal
0108-convert-sorted-array-to-binary-search-tree
0119-pascals-triangle-ii
0120-triangle
0123-best-time-to-buy-and-sell-stock-iii
0128-longest-consecutive-sequence
0130-surrounded-regions
0134-gas-station
0136-single-number
0139-word-break
0153-find-minimum-in-rotated-sorted-array
0169-majority-element
0188-best-time-to-buy-and-sell-stock-iv
0198-house-robber
0200-number-of-islands
0209-minimum-size-subarray-sum
0213-house-robber-ii
0215-kth-largest-element-in-an-array
0219-contains-duplicate-ii
0238-product-of-array-except-self
0240-search-a-2d-matrix-ii
0287-find-the-duplicate-number
0300-longest-increasing-subsequence
0325-maximum-size-subarray-sum-equals-k
0407-trapping-rain-water-ii
0416-partition-equal-subset-sum
0417-pacific-atlantic-water-flow
0448-find-all-numbers-disappeared-in-an-array
0474-ones-and-zeroes
0480-sliding-window-median
0485-max-consecutive-ones
0487-max-consecutive-ones-ii
0496-next-greater-element-i
0611-valid-triangle-number
0643-maximum-average-subarray-i
0645-set-mismatch
0714-best-time-to-buy-and-sell-stock-with-transaction-fee
0717-1-bit-and-2-bit-characters
0739-daily-temperatures
0759-set-intersection-size-at-least-two
0794-swim-in-rising-water
0797-rabbits-in-forest
0830-largest-triangle-area
0840-magic-squares-in-grid
0853-car-fleet
0875-koko-eating-bananas
0881-boats-to-save-people
0943-sum-of-subarray-minimums
0944-delete-columns-to-make-sorted
0945-snakes-and-ladders
0948-sort-an-array
0955-delete-columns-to-make-sorted-ii
0960-delete-columns-to-make-sorted-iii
0961-n-repeated-element-in-size-2n-array
1006-vowel-spellchecker
1008-construct-binary-search-tree-from-preorder-traversal
1018-largest-perimeter-triangle
1018-binary-prefix-divisible-by-5
1019-next-greater-node-in-linked-list
1025-minimum-cost-for-tickets
1046-max-consecutive-ones-iii
1049-minimum-domino-rotations-for-equal-row
1063-best-sightseeing-pair
1067-campus-bikes-ii
1098-largest-unique-number
1102-check-if-a-number-is-majority-element-in-a-sorted-array
1108-analyze-user-website-visit-pattern
1111-minimum-score-triangulation-of-polygon
1227-number-of-equivalent-domino-pairs
1262-greatest-sum-divisible-by-three
1353-find-resultant-array-after-removing-anagrams
1356-sort-integers-by-the-number-of-1-bits
1390-four-divisors
1421-find-numbers-with-even-number-of-digits
1426-find-n-unique-integers-sum-up-to-zero
1438-longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit
1458-max-dot-product-of-two-subsequences
1472-design-browser-history
1478-maximum-number-of-events-that-can-be-attended
1482-how-many-numbers-are-smaller-than-the-current-number
1524-number-of-sub-arrays-with-odd-sum
1536-minimum-swaps-to-arrange-a-binary-grid
1548-check-if-all-1s-are-at-least-length-k-places-away
1580-shuffle-the-array
1590-make-sum-divisible-by-p
1612-avoid-flood-in-the-city
1626-can-make-arithmetic-progression-from-sequence
1633-minimum-number-of-increments-on-subarrays-to-form-a-target-array
1642-furthest-building-you-can-reach
1656-count-good-triplets
1700-minimum-time-to-make-rope-colorful
1755-defuse-the-bomb
1769-minimum-number-of-operations-to-move-all-balls-to-each-box
1814-count-nice-pairs-in-an-array
1834-minimum-number-of-people-to-teach
1917-maximum-average-pass-ratio
1970-last-day-where-you-can-still-cross
1975-maximum-matrix-sum
1984-minimum-difference-between-highest-and-lowest-of-k-scores
1993-sum-of-all-subset-xor-totals
2003-distinct-numbers-in-each-subarray
2023-design-movie-rental-system
2048-build-array-from-permutation
2054-two-best-non-overlapping-events
2110-number-of-smooth-descent-periods-of-a-stock
2141-maximum-running-time-of-n-computers
2160-minimum-operations-to-make-a-uni-value-grid
2164-two-best-non-overlapping-events
2169-simple-bank-system
2220-find-all-possible-recipes-from-given-supplies
2244-number-of-laser-beams-in-a-bank
2249-count-the-hidden-sequences
2262-solving-questions-with-brainpower
2274-keep-multiplying-found-values-by-two
2277-count-equal-and-divisible-pairs-in-an-array
2280-count-good-triplets-in-an-array
2307-replace-non-coprime-numbers-in-array
2324-find-triangular-sum-of-an-array
2343-count-unguarded-cells-in-the-grid
2402-meeting-rooms-iii
2429-design-a-food-rating-system
2432-number-of-zero-filled-subarrays
2435-paths-in-matrix-whose-sum-is-divisible-by-k
2453-destroy-sequential-targets
2527-count-subarrays-with-fixed-bounds
2618-maximize-the-minimum-powered-city
2625-increment-submatrices-by-one
2626-count-the-number-of-good-subarrays
2661-smallest-missing-non-negative-integer-after-operations
2699-count-the-number-of-fair-pairs
2753-minimum-number-of-operations-to-make-all-array-elements-equal-to-1
2856-count-complete-subarrays-in-an-array
2888-minimum-index-of-a-valid-split
2915-count-of-interesting-subarrays
2975-maximum-square-area-by-removing-fences-from-a-field
2976-minimum-cost-to-convert-string-i
3013-divide-an-array-into-subarrays-with-minimum-cost-ii
3074-apple-redistribution-into-boxes
3075-maximize-happiness-of-selected-children
3096-minimum-levels-to-gain-more-points
3152-maximum-value-of-an-ordered-triplet-ii
3154-maximum-value-of-an-ordered-triplet-i
3171-minimum-equal-sum-of-two-arrays-after-replacing-zeros
3213-count-subarrays-where-max-element-appears-at-least-k-times
3242-count-elements-with-maximum-frequency
3277-find-the-number-of-ways-to-place-people-ii
3278-find-the-number-of-ways-to-place-people-i
3314-construct-the-minimum-bitwise-array-i
3315-construct-the-minimum-bitwise-array-ii
3332-maximum-points-tourist-can-earn
3381-maximum-subarray-sum-with-length-divisible-by-k
3383-taking-maximum-energy-from-the-mystic-dungeon
3430-count-days-without-meetings
3432-count-partitions-with-even-sum-difference
3433-count-mentions-per-user
3437-maximum-total-damage-with-spell-casting
3453-separate-squares-i
3475-minimum-operations-to-make-binary-array-elements-equal-to-one-i
3476-find-minimum-operations-to-make-all-elements-divisible-by-three
3501-delete-nodes-from-linked-list-present-in-array
3510-minimum-pair-removal-to-sort-array-ii
3531-count-covered-buildings
3562-maximum-profit-from-trading-stocks-with-discounts
3573-best-time-to-buy-and-sell-stock-v
3577-count-the-number-of-computer-unlocking-permutations
3592-find-x-sum-of-all-k-long-subarrays-ii
3606-coupon-code-validator
3610-find-x-sum-of-all-k-long-subarrays-i
3612-adjacent-increasing-subarrays-detection-i
3616-make-array-elements-equal-to-zero
3619-adjacent-increasing-subarrays-detection-ii
3620-maximum-number-of-distinct-elements-after-operations
3623-count-number-of-trapezoids-i
3627-find-minimum-time-to-reach-last-room-i
3628-find-minimum-time-to-reach-last-room-ii
3634-minimum-removals-to-balance-array
3637-trionic-array-i
3640-maximum-frequency-of-an-element-after-performing-operations-ii
3640-trionic-array-ii
3648-find-the-maximum-number-of-fruits-collected
3652-best-time-to-buy-and-sell-stock-using-strategy
3656-minimum-number-of-operations-to-make-elements-in-array-distinct
3685-count-subarrays-of-length-three-with-a-condition
3744-minimum-operations-to-make-array-elements-zero
3748-sort-matrix-by-diagonals
3790-fruits-into-baskets-ii
3794-find-the-minimum-amount-of-time-to-brew-potions
3797-design-spreadsheet
3827-implement-router
3863-power-grid-maintenance

Hash Table

0001-two-sum
0003-longest-substring-without-repeating-characters
0013-roman-to-integer
0017-letter-combinations-of-a-phone-number
0036-valid-sudoku
0049-group-anagrams
0106-construct-binary-tree-from-inorder-and-postorder-traversal
0128-longest-consecutive-sequence
0139-word-break
0166-fraction-to-recurring-decimal
0169-majority-element
0202-happy-number
0205-isomorphic-strings
0208-implement-trie-prefix-tree
0219-contains-duplicate-ii
0266-palindrome-permutation
0325-maximum-size-subarray-sum-equals-k
0359-logger-rate-limiter
0424-longest-repeating-character-replacement
0448-find-all-numbers-disappeared-in-an-array
0480-sliding-window-median
0496-next-greater-element-i
0645-set-mismatch
0756-pyramid-transition-matrix
0768-partition-labels
0797-rabbits-in-forest
0840-magic-squares-in-grid
0865-smallest-subtree-with-all-the-deepest-nodes
0961-n-repeated-element-in-size-2n-array
1006-vowel-spellchecker
1015-smallest-integer-divisible-by-k
1084-find-k-length-substrings-with-no-repeated-characters
1098-largest-unique-number
1108-analyze-user-website-visit-pattern
1218-lowest-common-ancestor-of-deepest-leaves
1227-number-of-equivalent-domino-pairs
1264-maximum-number-of-words-you-can-type
1353-find-resultant-array-after-removing-anagrams
1443-minimum-time-to-collect-all-apples-in-a-tree
1482-how-many-numbers-are-smaller-than-the-current-number
1500-count-largest-group
1590-make-sum-divisible-by-p
1612-avoid-flood-in-the-city
1814-count-nice-pairs-in-an-array
1834-minimum-number-of-people-to-teach
1960-check-if-the-sentence-is-pangram
2003-distinct-numbers-in-each-subarray
2023-design-movie-rental-system
2053-check-if-all-characters-have-equal-number-of-occurrences
2059-unique-length-3-palindromic-subsequences
2169-simple-bank-system
2174-next-greater-numerically-balanced-number
2220-find-all-possible-recipes-from-given-supplies
2274-keep-multiplying-found-values-by-two
2402-meeting-rooms-iii
2427-first-letter-to-appear-twice
2429-design-a-food-rating-system
2453-destroy-sequential-targets
2626-count-the-number-of-good-subarrays
2661-smallest-missing-non-negative-integer-after-operations
2856-count-complete-subarrays-in-an-array
2888-minimum-index-of-a-valid-split
2915-count-of-interesting-subarrays
2975-maximum-square-area-by-removing-fences-from-a-field
3013-divide-an-array-into-subarrays-with-minimum-cost-ii
3121-count-the-number-of-special-characters-ii
3242-count-elements-with-maximum-frequency
3381-maximum-subarray-sum-with-length-divisible-by-k
3437-maximum-total-damage-with-spell-casting
3501-delete-nodes-from-linked-list-present-in-array
3510-minimum-pair-removal-to-sort-array-ii
3531-count-covered-buildings
3592-find-x-sum-of-all-k-long-subarrays-ii
3606-coupon-code-validator
3610-find-x-sum-of-all-k-long-subarrays-i
3623-count-number-of-trapezoids-i
3656-minimum-number-of-operations-to-make-elements-in-array-distinct
3678-design-task-manager
3713-longest-balanced-substring-i
3714-longest-balanced-substring-ii
3797-design-spreadsheet
3827-implement-router
3863-power-grid-maintenance
3872-find-most-frequent-vowel-and-consonant

Bit Manipulation

0067-add-binary
0078-subsets
0136-single-number
0190-reverse-bits
0191-number-of-1-bits
0266-palindrome-permutation
0287-find-the-duplicate-number
0338-counting-bits
0401-binary-watch
0645-set-mismatch
0756-pyramid-transition-matrix
0762-prime-number-of-set-bits-in-binary-representation
0868-binary-gap
1018-binary-prefix-divisible-by-5
1067-campus-bikes-ii
1356-sort-integers-by-the-number-of-1-bits
1993-sum-of-all-subset-xor-totals
2059-unique-length-3-palindromic-subsequences
2427-first-letter-to-appear-twice
2837-minimum-operations-to-make-the-integer-zero
3314-construct-the-minimum-bitwise-array-i
3315-construct-the-minimum-bitwise-array-ii
3475-minimum-operations-to-make-binary-array-elements-equal-to-one-i
3676-smallest-number-with-all-set-bits
3744-minimum-operations-to-make-array-elements-zero

Counting

0169-majority-element
1227-number-of-equivalent-domino-pairs
1356-sort-integers-by-the-number-of-1-bits
1419-minimum-number-of-frogs-croaking
1814-count-nice-pairs-in-an-array
2053-check-if-all-characters-have-equal-number-of-occurrences
2174-next-greater-numerically-balanced-number
2427-first-letter-to-appear-twice
2453-destroy-sequential-targets
3242-count-elements-with-maximum-frequency
3437-maximum-total-damage-with-spell-casting
3493-maximum-number-of-operations-to-move-ones-to-the-end
3713-longest-balanced-substring-i
3872-find-most-frequent-vowel-and-consonant

Sliding Window

0003-longest-substring-without-repeating-characters
0209-minimum-size-subarray-sum
0219-contains-duplicate-ii
0424-longest-repeating-character-replacement
0480-sliding-window-median
0487-max-consecutive-ones-ii
0643-maximum-average-subarray-i
1046-max-consecutive-ones-iii
1084-find-k-length-substrings-with-no-repeated-characters
1438-longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit
1755-defuse-the-bomb
1984-minimum-difference-between-highest-and-lowest-of-k-scores
2003-distinct-numbers-in-each-subarray
2527-count-subarrays-with-fixed-bounds
2618-maximize-the-minimum-powered-city
2626-count-the-number-of-good-subarrays
2856-count-complete-subarrays-in-an-array
3013-divide-an-array-into-subarrays-with-minimum-cost-ii
3213-count-subarrays-where-max-element-appears-at-least-k-times
3475-minimum-operations-to-make-binary-array-elements-equal-to-one-i
3479-count-the-number-of-substrings-with-dominant-ones
3543-count-substrings-that-satisfy-k-constraint-i
3592-find-x-sum-of-all-k-long-subarrays-ii
3610-find-x-sum-of-all-k-long-subarrays-i
3634-minimum-removals-to-balance-array
3640-maximum-frequency-of-an-element-after-performing-operations-ii
3652-best-time-to-buy-and-sell-stock-using-strategy

Tree

0101-symmetric-tree
0102-binary-tree-level-order-traversal
0103-binary-tree-zigzag-level-order-traversal
0106-construct-binary-tree-from-inorder-and-postorder-traversal
0108-convert-sorted-array-to-binary-search-tree
0112-path-sum
0114-flatten-binary-tree-to-linked-list
0117-populating-next-right-pointers-in-each-node-ii
0226-invert-binary-tree
0236-lowest-common-ancestor-of-a-binary-tree
0530-minimum-absolute-difference-in-bst
0637-average-of-levels-in-binary-tree
0865-smallest-subtree-with-all-the-deepest-nodes
0894-all-possible-full-binary-trees
1008-construct-binary-search-tree-from-preorder-traversal
1022-sum-of-root-to-leaf-binary-numbers
1030-smallest-string-starting-from-leaf
1093-recover-a-tree-from-preorder-traversal
1161-maximum-level-sum-of-a-binary-tree
1218-lowest-common-ancestor-of-deepest-leaves
1339-maximum-product-of-splitted-binary-tree
1443-minimum-time-to-collect-all-apples-in-a-tree
2096-step-by-step-directions-from-a-binary-tree-node-to-another
2872-maximum-number-of-k-divisible-components
3562-maximum-profit-from-trading-stocks-with-discounts

Depth-First Search

0079-word-search
0101-symmetric-tree
0112-path-sum
0114-flatten-binary-tree-to-linked-list
0117-populating-next-right-pointers-in-each-node-ii
0130-surrounded-regions
0200-number-of-islands
0207-course-schedule
0210-course-schedule-ii
0226-invert-binary-tree
0236-lowest-common-ancestor-of-a-binary-tree
0417-pacific-atlantic-water-flow
0530-minimum-absolute-difference-in-bst
0637-average-of-levels-in-binary-tree
0744-network-delay-time
0794-swim-in-rising-water
0813-all-paths-from-source-to-target
0865-smallest-subtree-with-all-the-deepest-nodes
1022-sum-of-root-to-leaf-binary-numbers
1030-smallest-string-starting-from-leaf
1093-recover-a-tree-from-preorder-traversal
1161-maximum-level-sum-of-a-binary-tree
1218-lowest-common-ancestor-of-deepest-leaves
1339-maximum-product-of-splitted-binary-tree
1443-minimum-time-to-collect-all-apples-in-a-tree
1747-lexicographically-smallest-string-after-applying-operations
1970-last-day-where-you-can-still-cross
2092-find-all-people-with-secret
2096-step-by-step-directions-from-a-binary-tree-node-to-another
2793-count-the-number-of-complete-components
2872-maximum-number-of-k-divisible-components
3562-maximum-profit-from-trading-stocks-with-discounts
3863-power-grid-maintenance

Breadth-First Search

0101-symmetric-tree
0102-binary-tree-level-order-traversal
0103-binary-tree-zigzag-level-order-traversal
0112-path-sum
0117-populating-next-right-pointers-in-each-node-ii
0130-surrounded-regions
0200-number-of-islands
0207-course-schedule
0210-course-schedule-ii
0226-invert-binary-tree
0407-trapping-rain-water-ii
0417-pacific-atlantic-water-flow
0530-minimum-absolute-difference-in-bst
0637-average-of-levels-in-binary-tree
0744-network-delay-time
0794-swim-in-rising-water
0813-all-paths-from-source-to-target
0865-smallest-subtree-with-all-the-deepest-nodes
0945-snakes-and-ladders
1161-maximum-level-sum-of-a-binary-tree
1218-lowest-common-ancestor-of-deepest-leaves
1443-minimum-time-to-collect-all-apples-in-a-tree
1747-lexicographically-smallest-string-after-applying-operations
1970-last-day-where-you-can-still-cross
2092-find-all-people-with-secret
2793-count-the-number-of-complete-components
3863-power-grid-maintenance

Binary Tree

0101-symmetric-tree
0102-binary-tree-level-order-traversal
0103-binary-tree-zigzag-level-order-traversal
0106-construct-binary-tree-from-inorder-and-postorder-traversal
0108-convert-sorted-array-to-binary-search-tree
0112-path-sum
0114-flatten-binary-tree-to-linked-list
0117-populating-next-right-pointers-in-each-node-ii
0226-invert-binary-tree
0236-lowest-common-ancestor-of-a-binary-tree
0530-minimum-absolute-difference-in-bst
0637-average-of-levels-in-binary-tree
0865-smallest-subtree-with-all-the-deepest-nodes
0894-all-possible-full-binary-trees
1008-construct-binary-search-tree-from-preorder-traversal
1022-sum-of-root-to-leaf-binary-numbers
1030-smallest-string-starting-from-leaf
1093-recover-a-tree-from-preorder-traversal
1161-maximum-level-sum-of-a-binary-tree
1218-lowest-common-ancestor-of-deepest-leaves
1339-maximum-product-of-splitted-binary-tree
2096-step-by-step-directions-from-a-binary-tree-node-to-another

Binary Search Tree

0004-median-of-two-sorted-arrays
0033-search-in-rotated-sorted-array
0034-find-first-and-last-position-of-element-in-sorted-array
0074-search-a-2d-matrix
0081-search-in-rotated-sorted-array-ii
0108-convert-sorted-array-to-binary-search-tree
0153-find-minimum-in-rotated-sorted-array
0209-minimum-size-subarray-sum
0240-search-a-2d-matrix-ii
0287-find-the-duplicate-number
0300-longest-increasing-subsequence
0530-minimum-absolute-difference-in-bst
0611-valid-triangle-number
0794-swim-in-rising-water
0875-koko-eating-bananas
1008-construct-binary-search-tree-from-preorder-traversal
1046-max-consecutive-ones-iii
1051-shortest-way-to-form-string
1102-check-if-a-number-is-majority-element-in-a-sorted-array
1612-avoid-flood-in-the-city
1970-last-day-where-you-can-still-cross
2054-two-best-non-overlapping-events
2141-maximum-running-time-of-n-computers
2164-two-best-non-overlapping-events
2280-count-good-triplets-in-an-array
2618-maximize-the-minimum-powered-city
2699-count-the-number-of-fair-pairs
3437-maximum-total-damage-with-spell-casting
3453-separate-squares-i
3619-adjacent-increasing-subarrays-detection-ii
3640-maximum-frequency-of-an-element-after-performing-operations-ii
3790-fruits-into-baskets-ii
3827-implement-router

Simulation

0067-add-binary
2048-build-array-from-permutation
2169-simple-bank-system
2211-count-collisions-on-a-road
2274-keep-multiplying-found-values-by-two
2324-find-triangular-sum-of-an-array
2343-count-unguarded-cells-in-the-grid
2402-meeting-rooms-iii
2408-number-of-people-aware-of-a-secret
3336-water-bottles-ii
3433-count-mentions-per-user
3510-minimum-pair-removal-to-sort-array-ii
3616-make-array-elements-equal-to-zero
3768-check-if-digits-are-equal-in-string-after-operations-i
3790-fruits-into-baskets-ii
3794-find-the-minimum-amount-of-time-to-brew-potions

Two Pointers

0005-longest-palindromic-substring
0011-container-with-most-water
0015-3sum
0016-3sum-closest
0018-4sum
0028-find-the-index-of-the-first-occurrence-in-a-string
0042-trapping-rain-water
0075-sort-colors
0125-valid-palindrome
0151-reverse-words-in-a-string
0165-compare-version-numbers
0202-happy-number
0287-find-the-duplicate-number
0611-valid-triangle-number
0768-partition-labels
0881-boats-to-save-people
0908-middle-of-the-linked-list
1051-shortest-way-to-form-string
2699-count-the-number-of-fair-pairs
3437-maximum-total-damage-with-spell-casting

Linked List

0002-add-two-numbers
0025-reverse-nodes-in-k-group
0114-flatten-binary-tree-to-linked-list
0117-populating-next-right-pointers-in-each-node-ii
0908-middle-of-the-linked-list
1019-next-greater-node-in-linked-list
1472-design-browser-history
1618-delete-n-nodes-after-m-nodes-of-a-linked-list
2487-remove-nodes-from-linked-list
3501-delete-nodes-from-linked-list-present-in-array
3510-minimum-pair-removal-to-sort-array-ii

Recursion

0002-add-two-numbers
0025-reverse-nodes-in-k-group
0894-all-possible-full-binary-trees
2050-count-good-numbers
2487-remove-nodes-from-linked-list

String Matching

0028-find-the-index-of-the-first-occurrence-in-a-string

Dynamic Programming

0005-longest-palindromic-substring
0022-generate-parentheses
0042-trapping-rain-water
0045-jump-game-ii
0053-maximum-subarray
0062-unique-paths
0063-unique-paths-ii
0064-minimum-path-sum
0072-edit-distance
0097-interleaving-string
0119-pascals-triangle-ii
0120-triangle
0123-best-time-to-buy-and-sell-stock-iii
0139-word-break
0188-best-time-to-buy-and-sell-stock-iv
0198-house-robber
0213-house-robber-ii
0300-longest-increasing-subsequence
0338-counting-bits
0416-partition-equal-subset-sum
0474-ones-and-zeroes
0487-max-consecutive-ones-ii
0712-minimum-ascii-delete-sum-for-two-strings
0714-best-time-to-buy-and-sell-stock-with-transaction-fee
0799-champagne-tower
0894-all-possible-full-binary-trees
0943-sum-of-subarray-minimums
0960-delete-columns-to-make-sorted-iii
1025-minimum-cost-for-tickets
1063-best-sightseeing-pair
1067-campus-bikes-ii
1111-minimum-score-triangulation-of-polygon
1250-longest-common-subsequence
1262-greatest-sum-divisible-by-three
1458-max-dot-product-of-two-subsequences
1524-number-of-sub-arrays-with-odd-sum
1633-minimum-number-of-increments-on-subarrays-to-form-a-target-array
1653-minimum-deletions-to-make-string-balanced
1700-minimum-time-to-make-rope-colorful
2054-two-best-non-overlapping-events
2110-number-of-smooth-descent-periods-of-a-stock
2147-number-of-ways-to-divide-a-long-corridor
2164-two-best-non-overlapping-events
2262-solving-questions-with-brainpower
2408-number-of-people-aware-of-a-secret
2435-paths-in-matrix-whose-sum-is-divisible-by-k
3273-most-expensive-item-that-can-not-be-bought
3332-maximum-points-tourist-can-earn
3437-maximum-total-damage-with-spell-casting
3562-maximum-profit-from-trading-stocks-with-discounts
3573-best-time-to-buy-and-sell-stock-v
3640-trionic-array-ii
3648-find-the-maximum-number-of-fruits-collected

Prefix Sum

0209-minimum-size-subarray-sum
0238-product-of-array-except-self
0325-maximum-size-subarray-sum-equals-k
1046-max-consecutive-ones-iii
1524-number-of-sub-arrays-with-odd-sum
1590-make-sum-divisible-by-p
1769-minimum-number-of-operations-to-move-all-balls-to-each-box
2059-unique-length-3-palindromic-subsequences
2249-count-the-hidden-sequences
2483-minimum-penalty-for-a-shop
2618-maximize-the-minimum-powered-city
2625-increment-submatrices-by-one
2915-count-of-interesting-subarrays
3096-minimum-levels-to-gain-more-points
3381-maximum-subarray-sum-with-length-divisible-by-k
3383-taking-maximum-energy-from-the-mystic-dungeon
3432-count-partitions-with-even-sum-difference
3475-minimum-operations-to-make-binary-array-elements-equal-to-one-i
3616-make-array-elements-equal-to-zero
3640-maximum-frequency-of-an-element-after-performing-operations-ii
3652-best-time-to-buy-and-sell-stock-using-strategy
3714-longest-balanced-substring-ii
3794-find-the-minimum-amount-of-time-to-brew-potions

Sorting

0015-3sum
0016-3sum-closest
0018-4sum
0049-group-anagrams
0075-sort-colors
0169-majority-element
0215-kth-largest-element-in-an-array
0611-valid-triangle-number
0645-set-mismatch
0759-set-intersection-size-at-least-two
0761-special-binary-string
0853-car-fleet
0881-boats-to-save-people
0948-sort-an-array
1018-largest-perimeter-triangle
1098-largest-unique-number
1108-analyze-user-website-visit-pattern
1262-greatest-sum-divisible-by-three
1353-find-resultant-array-after-removing-anagrams
1356-sort-integers-by-the-number-of-1-bits
1478-maximum-number-of-events-that-can-be-attended
1482-how-many-numbers-are-smaller-than-the-current-number
1626-can-make-arithmetic-progression-from-sequence
1984-minimum-difference-between-highest-and-lowest-of-k-scores
2054-two-best-non-overlapping-events
2092-find-all-people-with-secret
2141-maximum-running-time-of-n-computers
2160-minimum-operations-to-make-a-uni-value-grid
2164-two-best-non-overlapping-events
2274-keep-multiplying-found-values-by-two
2402-meeting-rooms-iii
2699-count-the-number-of-fair-pairs
2887-sort-vowels-in-a-string
2888-minimum-index-of-a-valid-split
3074-apple-redistribution-into-boxes
3075-maximize-happiness-of-selected-children
3277-find-the-number-of-ways-to-place-people-ii
3278-find-the-number-of-ways-to-place-people-i
3430-count-days-without-meetings
3433-count-mentions-per-user
3437-maximum-total-damage-with-spell-casting
3531-count-covered-buildings
3606-coupon-code-validator
3620-maximum-number-of-distinct-elements-after-operations
3634-minimum-removals-to-balance-array
3640-maximum-frequency-of-an-element-after-performing-operations-ii
3748-sort-matrix-by-diagonals

Union Find

0128-longest-consecutive-sequence
0130-surrounded-regions
0200-number-of-islands
0794-swim-in-rising-water
1970-last-day-where-you-can-still-cross
2092-find-all-people-with-secret
2793-count-the-number-of-complete-components
3863-power-grid-maintenance

Graph

0207-course-schedule
0210-course-schedule-ii
0744-network-delay-time
0813-all-paths-from-source-to-target
2092-find-all-people-with-secret
2220-find-all-possible-recipes-from-given-supplies
2793-count-the-number-of-complete-components
3627-find-minimum-time-to-reach-last-room-i
3628-find-minimum-time-to-reach-last-room-ii
3863-power-grid-maintenance

Topological Sort

0207-course-schedule
0210-course-schedule-ii
2220-find-all-possible-recipes-from-given-supplies

Matrix

0036-valid-sudoku
0063-unique-paths-ii
0064-minimum-path-sum
0074-search-a-2d-matrix
0079-word-search
0130-surrounded-regions
0200-number-of-islands
0240-search-a-2d-matrix-ii
0407-trapping-rain-water-ii
0417-pacific-atlantic-water-flow
0794-swim-in-rising-water
0840-magic-squares-in-grid
0945-snakes-and-ladders
1536-minimum-swaps-to-arrange-a-binary-grid
1970-last-day-where-you-can-still-cross
1975-maximum-matrix-sum
2160-minimum-operations-to-make-a-uni-value-grid
2244-number-of-laser-beams-in-a-bank
2343-count-unguarded-cells-in-the-grid
2435-paths-in-matrix-whose-sum-is-divisible-by-k
2625-increment-submatrices-by-one
3332-maximum-points-tourist-can-earn
3627-find-minimum-time-to-reach-last-room-i
3628-find-minimum-time-to-reach-last-room-ii
3648-find-the-maximum-number-of-fruits-collected
3748-sort-matrix-by-diagonals
3797-design-spreadsheet

Greedy

0011-container-with-most-water
0045-jump-game-ii
0134-gas-station
0611-valid-triangle-number
0714-best-time-to-buy-and-sell-stock-with-transaction-fee
0759-set-intersection-size-at-least-two
0768-partition-labels
0797-rabbits-in-forest
0881-boats-to-save-people
0955-delete-columns-to-make-sorted-ii
1018-largest-perimeter-triangle
1049-minimum-domino-rotations-for-equal-row
1051-shortest-way-to-form-string
1081-smallest-subsequence-of-distinct-characters
1262-greatest-sum-divisible-by-three
1478-maximum-number-of-events-that-can-be-attended
1536-minimum-swaps-to-arrange-a-binary-grid
1612-avoid-flood-in-the-city
1633-minimum-number-of-increments-on-subarrays-to-form-a-target-array
1642-furthest-building-you-can-reach
1700-minimum-time-to-make-rope-colorful
1834-minimum-number-of-people-to-teach
1917-maximum-average-pass-ratio
1975-maximum-matrix-sum
2141-maximum-running-time-of-n-computers
2345-minimum-number-of-operations-to-convert-time
2618-maximize-the-minimum-powered-city
2661-smallest-missing-non-negative-integer-after-operations
3074-apple-redistribution-into-boxes
3075-maximize-happiness-of-selected-children
3171-minimum-equal-sum-of-two-arrays-after-replacing-zeros
3493-maximum-number-of-operations-to-move-ones-to-the-end
3620-maximum-number-of-distinct-elements-after-operations

Divide and Conquer

0004-median-of-two-sorted-arrays
0053-maximum-subarray
0106-construct-binary-tree-from-inorder-and-postorder-traversal
0108-convert-sorted-array-to-binary-search-tree
0169-majority-element
0190-reverse-bits
0191-number-of-1-bits
0215-kth-largest-element-in-an-array
0240-search-a-2d-matrix-ii
0761-special-binary-string
0948-sort-an-array
2280-count-good-triplets-in-an-array

Backtracking

0017-letter-combinations-of-a-phone-number
0022-generate-parentheses
0039-combination-sum
0040-combination-sum-ii
0046-permutations
0051-n-queens
0052-n-queens-ii
0077-combinations
0078-subsets
0079-word-search
0401-binary-watch
0756-pyramid-transition-matrix
0813-all-paths-from-source-to-target
1030-smallest-string-starting-from-leaf
1067-campus-bikes-ii
1993-sum-of-all-subset-xor-totals
2174-next-greater-numerically-balanced-number

Design

0208-implement-trie-prefix-tree
0359-logger-rate-limiter
0901-online-stock-span
1472-design-browser-history
2023-design-movie-rental-system
2169-simple-bank-system
2429-design-a-food-rating-system
3678-design-task-manager
3797-design-spreadsheet
3827-implement-router

Trie

0139-word-break
0208-implement-trie-prefix-tree

Combinatorics

0062-unique-paths
1993-sum-of-all-subset-xor-totals
2324-find-triangular-sum-of-an-array
3577-count-the-number-of-computer-unlocking-permutations
3768-check-if-digits-are-equal-in-string-after-operations-i

Enumeration

1656-count-good-triplets
1747-lexicographically-smallest-string-after-applying-operations
1925-count-square-sum-triples
1993-sum-of-all-subset-xor-totals
2174-next-greater-numerically-balanced-number
2507-number-of-common-factors
2837-minimum-operations-to-make-the-integer-zero
2975-maximum-square-area-by-removing-fences-from-a-field
2998-count-symmetric-integers
3277-find-the-number-of-ways-to-place-people-ii
3278-find-the-number-of-ways-to-place-people-i
3479-count-the-number-of-substrings-with-dominant-ones
3713-longest-balanced-substring-i

Heap (Priority Queue)

0215-kth-largest-element-in-an-array
0407-trapping-rain-water-ii
0480-sliding-window-median
0744-network-delay-time
0794-swim-in-rising-water
0948-sort-an-array
1438-longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit
1478-maximum-number-of-events-that-can-be-attended
1612-avoid-flood-in-the-city
1642-furthest-building-you-can-reach
1917-maximum-average-pass-ratio
2023-design-movie-rental-system
2054-two-best-non-overlapping-events
2164-two-best-non-overlapping-events
2402-meeting-rooms-iii
2429-design-a-food-rating-system
3013-divide-an-array-into-subarrays-with-minimum-cost-ii
3510-minimum-pair-removal-to-sort-array-ii
3592-find-x-sum-of-all-k-long-subarrays-ii
3610-find-x-sum-of-all-k-long-subarrays-i
3627-find-minimum-time-to-reach-last-room-i
3628-find-minimum-time-to-reach-last-room-ii
3650-minimum-cost-path-with-edge-reversals
3678-design-task-manager
3863-power-grid-maintenance

Binary Indexed Tree

2280-count-good-triplets-in-an-array

Segment Tree

2280-count-good-triplets-in-an-array
3790-fruits-into-baskets-ii

Merge Sort

0948-sort-an-array
2280-count-good-triplets-in-an-array

Ordered Set

1438-longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit
2023-design-movie-rental-system
2280-count-good-triplets-in-an-array
2429-design-a-food-rating-system
3510-minimum-pair-removal-to-sort-array-ii
3678-design-task-manager
3790-fruits-into-baskets-ii
3827-implement-router
3863-power-grid-maintenance

Bucket Sort

0948-sort-an-array

Radix Sort

0948-sort-an-array

Counting Sort

0948-sort-an-array
1482-how-many-numbers-are-smaller-than-the-current-number

Shortest Path

0744-network-delay-time
2976-minimum-cost-to-convert-string-i
3627-find-minimum-time-to-reach-last-room-i
3628-find-minimum-time-to-reach-last-room-ii
3650-minimum-cost-path-with-edge-reversals

Quickselect

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

Memoization

0139-word-break
0894-all-possible-full-binary-trees

Queue

1438-longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit
2408-number-of-people-aware-of-a-secret
2527-count-subarrays-with-fixed-bounds
2618-maximize-the-minimum-powered-city
3475-minimum-operations-to-make-binary-array-elements-equal-to-one-i
3827-implement-router

Monotonic Queue

1438-longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit
2527-count-subarrays-with-fixed-bounds

Number Theory

1585-the-kth-factor-of-n
2307-replace-non-coprime-numbers-in-array
2507-number-of-common-factors
2753-minimum-number-of-operations-to-make-all-array-elements-equal-to-1
3273-most-expensive-item-that-can-not-be-bought
3768-check-if-digits-are-equal-in-string-after-operations-i

Data Stream

0359-logger-rate-limiter
0901-online-stock-span
1472-design-browser-history

Geometry

0830-largest-triangle-area
3277-find-the-number-of-ways-to-place-people-ii
3278-find-the-number-of-ways-to-place-people-i
3623-count-number-of-trapezoids-i

Bitmask

1067-campus-bikes-ii

Brainteaser

2837-minimum-operations-to-make-the-integer-zero
3462-vowels-game-in-a-string
3577-count-the-number-of-computer-unlocking-permutations

Monotonic Stack

0042-trapping-rain-water
0496-next-greater-element-i
0739-daily-temperatures
0853-car-fleet
0901-online-stock-span
0943-sum-of-subarray-minimums
1008-construct-binary-search-tree-from-preorder-traversal
1019-next-greater-node-in-linked-list
1081-smallest-subsequence-of-distinct-characters
1633-minimum-number-of-increments-on-subarrays-to-form-a-target-array
2487-remove-nodes-from-linked-list

Game Theory

3462-vowels-game-in-a-string

Doubly-Linked List

1472-design-browser-history
3510-minimum-pair-removal-to-sort-array-ii

Graph Theory

2976-minimum-cost-to-convert-string-i
3650-minimum-cost-path-with-edge-reversals