LeetCode Topics

Array

0001-two-sum
0004-median-of-two-sorted-arrays
0015-3sum
0016-3sum-closest
0033-search-in-rotated-sorted-array
0034-find-first-and-last-position-of-element-in-sorted-array
0035-search-insert-position
0039-combination-sum
0040-combination-sum-ii
0042-trapping-rain-water
0046-permutations
0051-n-queens
0053-maximum-subarray
0054-spiral-matrix
0059-spiral-matrix-ii
0063-unique-paths-ii
0066-plus-one
0073-set-matrix-zeroes
0074-search-a-2d-matrix
0075-sort-colors
0078-subsets
0079-word-search
0090-subsets-ii
0108-convert-sorted-array-to-binary-search-tree
0121-best-time-to-buy-and-sell-stock
0122-best-time-to-buy-and-sell-stock-ii
0136-single-number
0139-word-break
0140-word-break-ii
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
0189-rotate-array
0198-house-robber
0200-number-of-islands
0212-word-search-ii
0213-house-robber-ii
0217-contains-duplicate
0219-contains-duplicate-ii
0221-maximal-square
0238-product-of-array-except-self
0240-search-a-2d-matrix-ii
0247-strobogrammatic-number-ii
0252-meeting-rooms
0256-paint-house
0259-3sum-smaller
0265-paint-house-ii
0283-move-zeroes
0300-longest-increasing-subsequence
0307-range-sum-query-mutable
0322-coin-change
0347-top-k-frequent-elements
0361-bomb-enemy
0413-arithmetic-slices
0421-maximum-xor-of-two-numbers-in-an-array
0436-find-right-interval
0474-ones-and-zeroes
0490-the-maze
0496-next-greater-element-i
0500-keyboard-row
0503-next-greater-element-ii
0532-k-diff-pairs-in-an-array
0542-01-matrix
0560-subarray-sum-equals-k
0605-can-place-flowers
0616-add-bold-tag-in-string
0692-top-k-frequent-words
0695-max-area-of-island
0698-partition-to-k-equal-sum-subsets
0724-find-pivot-index
0739-daily-temperatures
0740-delete-and-earn
0745-find-smallest-letter-greater-than-target
0746-prefix-and-suffix-search
0792-binary-search
0827-expressive-words
0862-find-and-replace-in-string
0875-longest-mountain-in-array
0892-shortest-subarray-with-sum-at-least-k
0905-length-of-longest-fibonacci-subsequence
0906-walking-robot-simulation
0907-koko-eating-bananas
0917-boats-to-save-people
0926-find-and-replace-pattern
0940-fruit-into-baskets
1002-maximum-width-ramp
1019-squares-of-a-sorted-array
1034-subarrays-with-k-different-integers
1036-rotting-oranges
1059-missing-element-in-sorted-array
1066-fixed-point
1073-number-of-enclaves
1075-index-pairs-of-a-string
1138-grumpy-bookstore-owner
1143-find-smallest-common-element-in-all-rows
1171-shortest-path-in-binary-matrix
1256-rank-transform-of-an-array
1331-path-with-maximum-gold
1364-tuple-with-same-product
1396-count-servers-that-communicate
1421-find-numbers-with-even-number-of-digits
1447-jump-game-iv
1468-check-if-n-and-its-double-exist
1476-count-negative-numbers-in-a-sorted-matrix
1485-minimum-cost-to-make-at-least-one-valid-path-in-a-grid
1524-string-matching-in-an-array
1528-kids-with-the-greatest-number-of-candies
1631-number-of-sub-arrays-with-odd-sum
1659-get-the-maximum-score
1663-detect-cycles-in-2d-grid
1694-make-sum-divisible-by-p
1721-maximum-profit-of-operating-a-centennial-wheel
1755-defuse-the-bomb
1798-max-number-of-k-sum-pairs
1876-map-of-highest-peak
1878-check-if-array-is-sorted-and-rotated
1895-minimum-number-of-operations-to-move-all-balls-to-each-box
1927-maximum-ascending-subarray-sum
1951-find-the-winner-of-the-circular-game
1993-sum-of-all-subset-xor-totals
2006-find-the-student-that-will-replace-the-chalk
2048-build-array-from-permutation
2107-find-unique-binary-string
2132-convert-1d-array-into-2d-array
2265-partition-array-according-to-given-pivot
2280-count-good-triplets-in-an-array
2292-counting-words-with-a-given-prefix
2308-divide-array-into-equal-pairs
2358-number-of-ways-to-split-array
2411-spiral-matrix-iv
2448-count-number-of-bad-pairs
2465-shifting-letters-ii
2473-max-sum-of-a-pair-with-equal-sum-of-digits
2551-apply-operations-to-an-array
2552-maximum-sum-of-distinct-subarrays-with-length-k
2581-divide-players-into-teams-of-equal-skill
2626-count-the-number-of-good-subarrays
2685-first-completely-painted-row-or-column
2691-count-vowel-strings-in-ranges
2705-minimum-impossible-or
2707-merge-two-2d-arrays-by-summing-values
2764-maximum-number-of-fish-in-a-grid
2766-find-the-prefix-common-array-of-two-arrays
3142-longest-unequal-adjacent-groups-subsequence-ii
3143-longest-unequal-adjacent-groups-subsequence-i
3194-find-words-containing-character
3213-count-subarrays-where-max-element-appears-at-least-k-times
3227-find-missing-and-repeated-values
3309-count-prefix-and-suffix-pairs-i
3321-type-of-triangle
3332-minimum-operations-to-exceed-threshold-value-ii
3372-longest-strictly-increasing-or-strictly-decreasing-subarray
3429-special-array-i
3463-alternating-groups-i
3475-minimum-operations-to-make-binary-array-elements-equal-to-one-i
3621-minimum-operations-to-make-array-values-equal-to-k
3639-zero-array-transformation-i
3643-zero-array-transformation-ii
3656-minimum-number-of-operations-to-make-elements-in-array-distinct
3685-count-subarrays-of-length-three-with-a-condition
3773-minimum-pair-removal-to-sort-array-i
3795-zero-array-transformation-iv

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
0153-find-minimum-in-rotated-sorted-array
0162-find-peak-element
0167-two-sum-ii-input-array-is-sorted
0240-search-a-2d-matrix-ii
0259-3sum-smaller
0278-first-bad-version
0300-longest-increasing-subsequence
0367-valid-perfect-square
0374-guess-number-higher-or-lower
0436-find-right-interval
0532-k-diff-pairs-in-an-array
0745-find-smallest-letter-greater-than-target
0792-binary-search
0892-shortest-subarray-with-sum-at-least-k
0907-koko-eating-bananas
1023-time-based-key-value-store
1059-missing-element-in-sorted-array
1066-fixed-point
1143-find-smallest-common-element-in-all-rows
1468-check-if-n-and-its-double-exist
1476-count-negative-numbers-in-a-sorted-matrix
2006-find-the-student-that-will-replace-the-chalk
2134-maximize-the-confusion-of-an-exam
2280-count-good-triplets-in-an-array
3643-zero-array-transformation-ii

Simulation

0054-spiral-matrix
0059-spiral-matrix-ii
0412-fizz-buzz
0906-walking-robot-simulation
1721-maximum-profit-of-operating-a-centennial-wheel
1951-find-the-winner-of-the-circular-game
2006-find-the-student-that-will-replace-the-chalk
2021-remove-all-occurrences-of-a-substring
2048-build-array-from-permutation
2076-sum-of-digits-of-string-after-convert
2132-convert-1d-array-into-2d-array
2265-partition-array-according-to-given-pivot
2411-spiral-matrix-iv
2551-apply-operations-to-an-array
2800-minimum-string-length-after-removing-substrings
3332-minimum-operations-to-exceed-threshold-value-ii
3447-clear-digits
3773-minimum-pair-removal-to-sort-array-i

Prefix Sum

0238-product-of-array-except-self
0560-subarray-sum-equals-k
0724-find-pivot-index
0892-shortest-subarray-with-sum-at-least-k
1537-maximum-score-after-splitting-a-string
1631-number-of-sub-arrays-with-odd-sum
1694-make-sum-divisible-by-p
1895-minimum-number-of-operations-to-move-all-balls-to-each-box
2006-find-the-student-that-will-replace-the-chalk
2059-unique-length-3-palindromic-subsequences
2134-maximize-the-confusion-of-an-exam
2358-number-of-ways-to-split-array
2465-shifting-letters-ii
2691-count-vowel-strings-in-ranges
3475-minimum-operations-to-make-binary-array-elements-equal-to-one-i
3639-zero-array-transformation-i
3643-zero-array-transformation-ii

String

0003-longest-substring-without-repeating-characters
0006-zigzag-conversion
0008-string-to-integer-atoi
0014-longest-common-prefix
0017-letter-combinations-of-a-phone-number
0020-valid-parentheses
0079-word-search
0091-decode-ways
0097-interleaving-string
0125-valid-palindrome
0131-palindrome-partitioning
0139-word-break
0140-word-break-ii
0151-reverse-words-in-a-string
0205-isomorphic-strings
0208-implement-trie-prefix-tree
0212-word-search-ii
0242-valid-anagram
0247-strobogrammatic-number-ii
0290-word-pattern
0344-reverse-string
0345-reverse-vowels-of-a-string
0392-is-subsequence
0402-remove-k-digits
0412-fizz-buzz
0474-ones-and-zeroes
0500-keyboard-row
0606-construct-string-from-binary-tree
0616-add-bold-tag-in-string
0692-top-k-frequent-words
0746-prefix-and-suffix-search
0778-reorganize-string
0800-letter-case-permutation
0812-rotate-string
0827-expressive-words
0862-find-and-replace-in-string
0926-find-and-replace-pattern
0957-minimum-add-to-make-parentheses-valid
1023-time-based-key-value-store
1058-lexicographically-smallest-equivalent-string
1075-index-pairs-of-a-string
1146-greatest-common-divisor-of-strings
1250-longest-common-subsequence
1302-delete-characters-to-make-fancy-string
1430-find-the-k-beauty-of-a-number
1460-number-of-substrings-containing-all-three-characters
1502-construct-k-palindrome-strings
1524-string-matching-in-an-array
1537-maximum-score-after-splitting-a-string
1648-minimum-insertions-to-balance-a-parentheses-string
1894-merge-strings-alternately
1895-minimum-number-of-operations-to-move-all-balls-to-each-box
1915-check-if-one-string-swap-can-make-strings-equal
1987-substrings-of-size-three-with-distinct-characters
2021-remove-all-occurrences-of-a-substring
2059-unique-length-3-palindromic-subsequences
2076-sum-of-digits-of-string-after-convert
2095-minimum-number-of-swaps-to-make-the-string-balanced
2107-find-unique-binary-string
2134-maximize-the-confusion-of-an-exam
2292-counting-words-with-a-given-prefix
2463-minimum-recolors-to-get-k-consecutive-black-blocks
2465-shifting-letters-ii
2580-circular-sentence
2691-count-vowel-strings-in-ranges
2800-minimum-string-length-after-removing-substrings
3142-longest-unequal-adjacent-groups-subsequence-ii
3143-longest-unequal-adjacent-groups-subsequence-i
3174-minimum-number-of-changes-to-make-binary-string-beautiful
3194-find-words-containing-character
3309-count-prefix-and-suffix-pairs-i
3447-clear-digits
3451-string-compression-iii
3455-minimum-length-of-string-after-operations
3543-count-substrings-that-satisfy-k-constraint-i
3753-maximum-difference-between-even-and-odd-frequency-i

Matrix

0054-spiral-matrix
0059-spiral-matrix-ii
0063-unique-paths-ii
0073-set-matrix-zeroes
0074-search-a-2d-matrix
0079-word-search
0200-number-of-islands
0212-word-search-ii
0221-maximal-square
0240-search-a-2d-matrix-ii
0361-bomb-enemy
0490-the-maze
0542-01-matrix
0695-max-area-of-island
1036-rotting-oranges
1073-number-of-enclaves
1143-find-smallest-common-element-in-all-rows
1171-shortest-path-in-binary-matrix
1331-path-with-maximum-gold
1396-count-servers-that-communicate
1476-count-negative-numbers-in-a-sorted-matrix
1485-minimum-cost-to-make-at-least-one-valid-path-in-a-grid
1663-detect-cycles-in-2d-grid
1876-map-of-highest-peak
2132-convert-1d-array-into-2d-array
2411-spiral-matrix-iv
2685-first-completely-painted-row-or-column
2764-maximum-number-of-fish-in-a-grid
3227-find-missing-and-repeated-values

Hash Table

0001-two-sum
0003-longest-substring-without-repeating-characters
0017-letter-combinations-of-a-phone-number
0073-set-matrix-zeroes
0139-word-break
0140-word-break-ii
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
0314-binary-tree-vertical-order-traversal
0347-top-k-frequent-elements
0421-maximum-xor-of-two-numbers-in-an-array
0496-next-greater-element-i
0500-keyboard-row
0532-k-diff-pairs-in-an-array
0560-subarray-sum-equals-k
0616-add-bold-tag-in-string
0692-top-k-frequent-words
0694-number-of-distinct-islands
0740-delete-and-earn
0746-prefix-and-suffix-search
0778-reorganize-string
0862-find-and-replace-in-string
0905-length-of-longest-fibonacci-subsequence
0906-walking-robot-simulation
0926-find-and-replace-pattern
0940-fruit-into-baskets
1023-time-based-key-value-store
1029-vertical-order-traversal-of-a-binary-tree
1034-subarrays-with-k-different-integers
1143-find-smallest-common-element-in-all-rows
1256-rank-transform-of-an-array
1364-tuple-with-same-product
1447-jump-game-iv
1460-number-of-substrings-containing-all-three-characters
1468-check-if-n-and-its-double-exist
1500-count-largest-group
1502-construct-k-palindrome-strings
1694-make-sum-divisible-by-p
1798-max-number-of-k-sum-pairs
1915-check-if-one-string-swap-can-make-strings-equal
1987-substrings-of-size-three-with-distinct-characters
2059-unique-length-3-palindromic-subsequences
2107-find-unique-binary-string
2308-divide-array-into-equal-pairs
2448-count-number-of-bad-pairs
2473-max-sum-of-a-pair-with-equal-sum-of-digits
2552-maximum-sum-of-distinct-subarrays-with-length-k
2581-divide-players-into-teams-of-equal-skill
2626-count-the-number-of-good-subarrays
2685-first-completely-painted-row-or-column
2707-merge-two-2d-arrays-by-summing-values
2766-find-the-prefix-common-array-of-two-arrays
3227-find-missing-and-repeated-values
3455-minimum-length-of-string-after-operations
3621-minimum-operations-to-make-array-values-equal-to-k
3656-minimum-number-of-operations-to-make-elements-in-array-distinct
3753-maximum-difference-between-even-and-odd-frequency-i
3773-minimum-pair-removal-to-sort-array-i

Database

0176-second-highest-salary
0180-consecutive-numbers
0183-customers-who-never-order
0185-department-top-three-salaries
0196-delete-duplicate-emails
0197-rising-temperature
0570-managers-with-at-least-5-direct-reports
0577-employee-bonus
0584-find-customer-referee
0585-investments-in-2016
0586-customer-placing-the-largest-number-of-orders
0595-big-countries
0596-classes-more-than-5-students
0602-friend-requests-ii-who-has-the-most-friends
0610-triangle-judgement
0619-biggest-single-number
0620-not-boring-movies
0626-exchange-seats
1135-customers-who-bought-all-products
1153-product-sales-analysis-i
1155-product-sales-analysis-iii
1161-project-employees-i
1182-game-play-analysis-iv
1245-user-activity-for-the-past-30-days-i
1258-article-views-i
1278-product-price-at-a-given-date
1292-immediate-food-delivery-ii
1317-monthly-transactions-i
1327-last-person-to-fit-in-the-bus
1338-queries-quality-and-percentage
1390-average-selling-price
1415-students-and-examinations
1452-restaurant-growth
1462-list-the-products-ordered-in-a-period
1480-movie-rating
1509-replace-employee-id-with-the-unique-identifier
1625-group-sold-products-by-the-date
1664-find-users-with-valid-e-mails
1670-patients-with-a-condition
1724-customer-who-visited-but-did-not-make-any-transactions
1773-percentage-of-users-attended-a-contest
1801-average-time-of-process-per-machine
1811-fix-names-in-a-table
1827-invalid-tweets
1877-find-followers-count
1882-the-number-of-employees-which-report-to-each-employee
1908-recyclable-and-low-fat-products
1942-primary-department-for-each-employee
1974-find-customers-with-positive-revenue-this-year
2024-calculate-special-bonus
2057-count-salary-categories
2087-confirmation-rate
2127-employees-whose-manager-left-the-company
2495-number-of-unique-subjects-taught-by-each-teacher

Sorting

0015-3sum
0016-3sum-closest
0075-sort-colors
0169-majority-element
0217-contains-duplicate
0242-valid-anagram
0252-meeting-rooms
0259-3sum-smaller
0314-binary-tree-vertical-order-traversal
0347-top-k-frequent-elements
0436-find-right-interval
0532-k-diff-pairs-in-an-array
0692-top-k-frequent-words
0778-reorganize-string
0862-find-and-replace-in-string
0917-boats-to-save-people
1019-squares-of-a-sorted-array
1029-vertical-order-traversal-of-a-binary-tree
1075-index-pairs-of-a-string
1256-rank-transform-of-an-array
1468-check-if-n-and-its-double-exist
1798-max-number-of-k-sum-pairs
2473-max-sum-of-a-pair-with-equal-sum-of-digits
2581-divide-players-into-teams-of-equal-skill
3321-type-of-triangle

Dynamic Programming

0042-trapping-rain-water
0053-maximum-subarray
0062-unique-paths
0063-unique-paths-ii
0070-climbing-stairs
0091-decode-ways
0097-interleaving-string
0121-best-time-to-buy-and-sell-stock
0122-best-time-to-buy-and-sell-stock-ii
0131-palindrome-partitioning
0139-word-break
0140-word-break-ii
0152-maximum-product-subarray
0198-house-robber
0213-house-robber-ii
0221-maximal-square
0256-paint-house
0265-paint-house-ii
0276-paint-fence
0300-longest-increasing-subsequence
0322-coin-change
0338-counting-bits
0361-bomb-enemy
0392-is-subsequence
0397-integer-replacement
0413-arithmetic-slices
0474-ones-and-zeroes
0542-01-matrix
0650-2-keys-keyboard
0698-partition-to-k-equal-sum-subsets
0740-delete-and-earn
0875-longest-mountain-in-array
0905-length-of-longest-fibonacci-subsequence
1013-fibonacci-number
1236-n-th-tribonacci-number
1250-longest-common-subsequence
1631-number-of-sub-arrays-with-odd-sum
1659-get-the-maximum-score
3142-longest-unequal-adjacent-groups-subsequence-ii
3143-longest-unequal-adjacent-groups-subsequence-i
3795-zero-array-transformation-iv

Divide and Conquer

0004-median-of-two-sorted-arrays
0053-maximum-subarray
0108-convert-sorted-array-to-binary-search-tree
0169-majority-element
0240-search-a-2d-matrix-ii
0347-top-k-frequent-elements
2280-count-good-triplets-in-an-array

Counting

0169-majority-element
0347-top-k-frequent-elements
0692-top-k-frequent-words
0778-reorganize-string
1034-subarrays-with-k-different-integers
1143-find-smallest-common-element-in-all-rows
1364-tuple-with-same-product
1396-count-servers-that-communicate
1502-construct-k-palindrome-strings
1915-check-if-one-string-swap-can-make-strings-equal
1987-substrings-of-size-three-with-distinct-characters
2308-divide-array-into-equal-pairs
2448-count-number-of-bad-pairs
3455-minimum-length-of-string-after-operations
3753-maximum-difference-between-even-and-odd-frequency-i

Two Pointers

0015-3sum
0016-3sum-closest
0042-trapping-rain-water
0075-sort-colors
0125-valid-palindrome
0151-reverse-words-in-a-string
0167-two-sum-ii-input-array-is-sorted
0189-rotate-array
0202-happy-number
0234-palindrome-linked-list
0259-3sum-smaller
0283-move-zeroes
0344-reverse-string
0345-reverse-vowels-of-a-string
0392-is-subsequence
0532-k-diff-pairs-in-an-array
0827-expressive-words
0875-longest-mountain-in-array
0908-middle-of-the-linked-list
0917-boats-to-save-people
1019-squares-of-a-sorted-array
1468-check-if-n-and-its-double-exist
1659-get-the-maximum-score
1798-max-number-of-k-sum-pairs
1894-merge-strings-alternately
2095-minimum-number-of-swaps-to-make-the-string-balanced
2265-partition-array-according-to-given-pivot
2551-apply-operations-to-an-array
2581-divide-players-into-teams-of-equal-skill
2707-merge-two-2d-arrays-by-summing-values

Math

0007-reverse-integer
0009-palindrome-number
0050-powx-n
0062-unique-paths
0066-plus-one
0069-sqrtx
0070-climbing-stairs
0089-gray-code
0189-rotate-array
0202-happy-number
0367-valid-perfect-square
0412-fizz-buzz
0650-2-keys-keyboard
0767-prime-number-of-set-bits-in-binary-representation
1013-fibonacci-number
1090-armstrong-number
1146-greatest-common-divisor-of-strings
1236-n-th-tribonacci-number
1421-find-numbers-with-even-number-of-digits
1430-find-the-k-beauty-of-a-number
1500-count-largest-group
1631-number-of-sub-arrays-with-odd-sum
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
2050-count-good-numbers
2448-count-number-of-bad-pairs
2610-closest-prime-numbers-in-range
2649-count-total-number-of-colored-cells
2998-count-symmetric-integers
3227-find-missing-and-repeated-values
3321-type-of-triangle
3830-find-closest-person

Recursion

0050-powx-n
0234-palindrome-linked-list
0247-strobogrammatic-number-ii
1013-fibonacci-number
1951-find-the-winner-of-the-circular-game
2050-count-good-numbers

Memoization

0070-climbing-stairs
0139-word-break
0140-word-break-ii
0397-integer-replacement
0698-partition-to-k-equal-sum-subsets
1013-fibonacci-number
1236-n-th-tribonacci-number

Heap (Priority Queue)

0347-top-k-frequent-elements
0692-top-k-frequent-words
0778-reorganize-string
0892-shortest-subarray-with-sum-at-least-k
1485-minimum-cost-to-make-at-least-one-valid-path-in-a-grid
2473-max-sum-of-a-pair-with-equal-sum-of-digits
3332-minimum-operations-to-exceed-threshold-value-ii
3773-minimum-pair-removal-to-sort-array-i

Bucket Sort

0347-top-k-frequent-elements
0692-top-k-frequent-words

Quickselect

0347-top-k-frequent-elements

Stack

0020-valid-parentheses
0042-trapping-rain-water
0094-binary-tree-inorder-traversal
0144-binary-tree-preorder-traversal
0145-binary-tree-postorder-traversal
0234-palindrome-linked-list
0402-remove-k-digits
0496-next-greater-element-i
0503-next-greater-element-ii
0739-daily-temperatures
0957-minimum-add-to-make-parentheses-valid
1002-maximum-width-ramp
1648-minimum-insertions-to-balance-a-parentheses-string
2021-remove-all-occurrences-of-a-substring
2095-minimum-number-of-swaps-to-make-the-string-balanced
2800-minimum-string-length-after-removing-substrings
3447-clear-digits

Bit Manipulation

0078-subsets
0089-gray-code
0090-subsets-ii
0136-single-number
0338-counting-bits
0397-integer-replacement
0421-maximum-xor-of-two-numbers-in-an-array
0461-hamming-distance
0698-partition-to-k-equal-sum-subsets
0767-prime-number-of-set-bits-in-binary-representation
0800-letter-case-permutation
0899-binary-gap
1993-sum-of-all-subset-xor-totals
2059-unique-length-3-palindromic-subsequences
2308-divide-array-into-equal-pairs
2705-minimum-impossible-or
2766-find-the-prefix-common-array-of-two-arrays
3475-minimum-operations-to-make-binary-array-elements-equal-to-one-i

Greedy

0122-best-time-to-buy-and-sell-stock-ii
0397-integer-replacement
0402-remove-k-digits
0605-can-place-flowers
0778-reorganize-string
0917-boats-to-save-people
0957-minimum-add-to-make-parentheses-valid
1502-construct-k-palindrome-strings
1648-minimum-insertions-to-balance-a-parentheses-string
1659-get-the-maximum-score
2095-minimum-number-of-swaps-to-make-the-string-balanced
3143-longest-unequal-adjacent-groups-subsequence-i

Trie

0014-longest-common-prefix
0139-word-break
0140-word-break-ii
0208-implement-trie-prefix-tree
0212-word-search-ii
0421-maximum-xor-of-two-numbers-in-an-array
0616-add-bold-tag-in-string
0692-top-k-frequent-words
0746-prefix-and-suffix-search
1075-index-pairs-of-a-string
2009-longest-word-with-all-prefixes
3309-count-prefix-and-suffix-pairs-i

String Matching

0616-add-bold-tag-in-string
0812-rotate-string
1524-string-matching-in-an-array
2292-counting-words-with-a-given-prefix
3309-count-prefix-and-suffix-pairs-i

Monotonic Stack

0042-trapping-rain-water
0402-remove-k-digits
0496-next-greater-element-i
0503-next-greater-element-ii
0739-daily-temperatures
1002-maximum-width-ramp

Interactive

0278-first-bad-version
0374-guess-number-higher-or-lower

Tree

0094-binary-tree-inorder-traversal
0098-validate-binary-search-tree
0101-symmetric-tree
0102-binary-tree-level-order-traversal
0104-maximum-depth-of-binary-tree
0108-convert-sorted-array-to-binary-search-tree
0110-balanced-binary-tree
0112-path-sum
0113-path-sum-ii
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
0314-binary-tree-vertical-order-traversal
0437-path-sum-iii
0515-find-largest-value-in-each-tree-row
0538-convert-bst-to-greater-tree
0543-diameter-of-binary-tree
0545-boundary-of-binary-tree
0606-construct-string-from-binary-tree
0637-average-of-levels-in-binary-tree
1029-vertical-order-traversal-of-a-binary-tree
1114-binary-search-tree-to-greater-sum-tree

Depth-First Search

0079-word-search
0094-binary-tree-inorder-traversal
0098-validate-binary-search-tree
0101-symmetric-tree
0104-maximum-depth-of-binary-tree
0110-balanced-binary-tree
0112-path-sum
0113-path-sum-ii
0144-binary-tree-preorder-traversal
0145-binary-tree-postorder-traversal
0199-binary-tree-right-side-view
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
0236-lowest-common-ancestor-of-a-binary-tree
0310-minimum-height-trees
0314-binary-tree-vertical-order-traversal
0323-number-of-connected-components-in-an-undirected-graph
0437-path-sum-iii
0490-the-maze
0515-find-largest-value-in-each-tree-row
0538-convert-bst-to-greater-tree
0543-diameter-of-binary-tree
0545-boundary-of-binary-tree
0547-number-of-provinces
0606-construct-string-from-binary-tree
0637-average-of-levels-in-binary-tree
0684-redundant-connection
0694-number-of-distinct-islands
0695-max-area-of-island
0820-find-eventual-safe-states
0871-keys-and-rooms
1029-vertical-order-traversal-of-a-binary-tree
1073-number-of-enclaves
1114-binary-search-tree-to-greater-sum-tree
1300-critical-connections-in-a-network
1396-count-servers-that-communicate
1558-course-schedule-iv
1663-detect-cycles-in-2d-grid
2009-longest-word-with-all-prefixes
2764-maximum-number-of-fish-in-a-grid

Binary Tree

0094-binary-tree-inorder-traversal
0098-validate-binary-search-tree
0101-symmetric-tree
0102-binary-tree-level-order-traversal
0104-maximum-depth-of-binary-tree
0108-convert-sorted-array-to-binary-search-tree
0110-balanced-binary-tree
0112-path-sum
0113-path-sum-ii
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
0314-binary-tree-vertical-order-traversal
0437-path-sum-iii
0515-find-largest-value-in-each-tree-row
0538-convert-bst-to-greater-tree
0543-diameter-of-binary-tree
0545-boundary-of-binary-tree
0606-construct-string-from-binary-tree
0637-average-of-levels-in-binary-tree
1029-vertical-order-traversal-of-a-binary-tree
1114-binary-search-tree-to-greater-sum-tree

Backtracking

0017-letter-combinations-of-a-phone-number
0039-combination-sum
0040-combination-sum-ii
0046-permutations
0051-n-queens
0077-combinations
0078-subsets
0079-word-search
0089-gray-code
0090-subsets-ii
0113-path-sum-ii
0131-palindrome-partitioning
0140-word-break-ii
0212-word-search-ii
0254-factor-combinations
0698-partition-to-k-equal-sum-subsets
0800-letter-case-permutation
1331-path-with-maximum-gold
1993-sum-of-all-subset-xor-totals
2107-find-unique-binary-string

Breadth-First Search

0101-symmetric-tree
0102-binary-tree-level-order-traversal
0104-maximum-depth-of-binary-tree
0112-path-sum
0199-binary-tree-right-side-view
0200-number-of-islands
0207-course-schedule
0210-course-schedule-ii
0226-invert-binary-tree
0310-minimum-height-trees
0314-binary-tree-vertical-order-traversal
0322-coin-change
0323-number-of-connected-components-in-an-undirected-graph
0490-the-maze
0515-find-largest-value-in-each-tree-row
0542-01-matrix
0547-number-of-provinces
0637-average-of-levels-in-binary-tree
0684-redundant-connection
0694-number-of-distinct-islands
0695-max-area-of-island
0820-find-eventual-safe-states
0871-keys-and-rooms
1029-vertical-order-traversal-of-a-binary-tree
1036-rotting-oranges
1073-number-of-enclaves
1171-shortest-path-in-binary-matrix
1396-count-servers-that-communicate
1447-jump-game-iv
1485-minimum-cost-to-make-at-least-one-valid-path-in-a-grid
1558-course-schedule-iv
1663-detect-cycles-in-2d-grid
1876-map-of-highest-peak
2764-maximum-number-of-fish-in-a-grid

Union Find

0200-number-of-islands
0323-number-of-connected-components-in-an-undirected-graph
0547-number-of-provinces
0684-redundant-connection
0694-number-of-distinct-islands
0695-max-area-of-island
1058-lexicographically-smallest-equivalent-string
1073-number-of-enclaves
1396-count-servers-that-communicate
1663-detect-cycles-in-2d-grid
2764-maximum-number-of-fish-in-a-grid

Graph

0207-course-schedule
0210-course-schedule-ii
0310-minimum-height-trees
0323-number-of-connected-components-in-an-undirected-graph
0547-number-of-provinces
0684-redundant-connection
0820-find-eventual-safe-states
0871-keys-and-rooms
1101-parallel-courses
1300-critical-connections-in-a-network
1485-minimum-cost-to-make-at-least-one-valid-path-in-a-grid
1558-course-schedule-iv

Design

0208-implement-trie-prefix-tree
0307-range-sum-query-mutable
0746-prefix-and-suffix-search
1023-time-based-key-value-store

Rolling Hash

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

Hash Function

0694-number-of-distinct-islands
3309-count-prefix-and-suffix-pairs-i

Shortest Path

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

Topological Sort

0207-course-schedule
0210-course-schedule-ii
0310-minimum-height-trees
0820-find-eventual-safe-states
1101-parallel-courses
1558-course-schedule-iv

Sliding Window

0003-longest-substring-without-repeating-characters
0219-contains-duplicate-ii
0413-arithmetic-slices
0892-shortest-subarray-with-sum-at-least-k
0940-fruit-into-baskets
1034-subarrays-with-k-different-integers
1138-grumpy-bookstore-owner
1430-find-the-k-beauty-of-a-number
1460-number-of-substrings-containing-all-three-characters
1755-defuse-the-bomb
1987-substrings-of-size-three-with-distinct-characters
2134-maximize-the-confusion-of-an-exam
2463-minimum-recolors-to-get-k-consecutive-black-blocks
2552-maximum-sum-of-distinct-subarrays-with-length-k
2626-count-the-number-of-good-subarrays
3213-count-subarrays-where-max-element-appears-at-least-k-times
3463-alternating-groups-i
3475-minimum-operations-to-make-binary-array-elements-equal-to-one-i
3543-count-substrings-that-satisfy-k-constraint-i

Linked List

0234-palindrome-linked-list
0908-middle-of-the-linked-list
1618-delete-n-nodes-after-m-nodes-of-a-linked-list
2411-spiral-matrix-iv
3773-minimum-pair-removal-to-sort-array-i

Number Theory

2610-closest-prime-numbers-in-range

Brainteaser

2705-minimum-impossible-or

Queue

0892-shortest-subarray-with-sum-at-least-k
1951-find-the-winner-of-the-circular-game
3475-minimum-operations-to-make-binary-array-elements-equal-to-one-i

Binary Indexed Tree

0307-range-sum-query-mutable
2280-count-good-triplets-in-an-array

Segment Tree

0307-range-sum-query-mutable
2280-count-good-triplets-in-an-array

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
0538-convert-bst-to-greater-tree
1114-binary-search-tree-to-greater-sum-tree

Enumeration

0875-longest-mountain-in-array
1993-sum-of-all-subset-xor-totals
2998-count-symmetric-integers

Combinatorics

0062-unique-paths
1993-sum-of-all-subset-xor-totals

Monotonic Queue

0892-shortest-subarray-with-sum-at-least-k

Doubly-Linked List

3773-minimum-pair-removal-to-sort-array-i

Ordered Set

2280-count-good-triplets-in-an-array
3773-minimum-pair-removal-to-sort-array-i

Merge Sort

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

Biconnected Component

1300-critical-connections-in-a-network

Bitmask

0698-partition-to-k-equal-sum-subsets