LeetCode

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

LeetCode Topics

Linked List

0002-add-two-numbers
0019-remove-nth-node-from-end-of-list
0021-merge-two-sorted-lists
0141-linked-list-cycle
0160-intersection-of-two-linked-lists
0203-remove-linked-list-elements
0237-delete-node-in-a-linked-list
0908-middle-of-the-linked-list
1411-convert-binary-number-in-a-linked-list-to-integer
2182-find-the-minimum-and-maximum-number-of-nodes-between-critical-points
2299-merge-nodes-in-between-zeros

Simulation

0054-spiral-matrix
0067-add-binary
0657-robot-return-to-origin
1184-car-pooling
1642-water-bottles
1803-average-waiting-time
1951-find-the-winner-of-the-circular-game
2265-partition-array-according-to-given-pivot
2271-rearrange-array-elements-by-sign
2299-merge-nodes-in-between-zeros
2551-apply-operations-to-an-array
2645-pass-the-pillow
2846-robot-collisions

Two Pointers

0011-container-with-most-water
0015-3sum
0018-4sum
0019-remove-nth-node-from-end-of-list
0026-remove-duplicates-from-sorted-array
0027-remove-element
0028-find-the-index-of-the-first-occurrence-in-a-string
0031-next-permutation
0042-trapping-rain-water
0075-sort-colors
0088-merge-sorted-array
0125-valid-palindrome
0141-linked-list-cycle
0160-intersection-of-two-linked-lists
0167-two-sum-ii-input-array-is-sorted
0189-rotate-array
0202-happy-number
0283-move-zeroes
0287-find-the-duplicate-number
0349-intersection-of-two-arrays
0556-next-greater-element-iii
0768-partition-labels
0908-middle-of-the-linked-list
2128-reverse-prefix-of-word
2265-partition-array-according-to-given-pivot
2271-rearrange-array-elements-by-sign
2497-maximum-matching-of-players-with-trainers
2551-apply-operations-to-an-array
2588-maximum-number-of-points-from-grid-queries
2707-merge-two-2d-arrays-by-summing-values
3683-find-the-lexicographically-largest-string-from-the-box-i

String

0003-longest-substring-without-repeating-characters
0010-regular-expression-matching
0013-roman-to-integer
0020-valid-parentheses
0028-find-the-index-of-the-first-occurrence-in-a-string
0067-add-binary
0125-valid-palindrome
0127-word-ladder
0168-excel-sheet-column-title
0171-excel-sheet-column-number
0242-valid-anagram
0387-first-unique-character-in-a-string
0389-find-the-difference
0424-longest-repeating-character-replacement
0556-next-greater-element-iii
0657-robot-return-to-origin
0726-number-of-atoms
0768-partition-labels
0952-word-subsets
1006-vowel-spellchecker
1058-lexicographically-smallest-equivalent-string
1298-reverse-substrings-between-each-pair-of-parentheses
1302-delete-characters-to-make-fancy-string
1460-number-of-substrings-containing-all-three-characters
1502-construct-k-palindrome-strings
1537-maximum-score-after-splitting-a-string
1636-number-of-substrings-with-only-1s
1720-crawler-log-folder
1818-maximum-score-from-removing-substrings
1885-count-number-of-homogenous-substrings
2128-reverse-prefix-of-word
2220-find-all-possible-recipes-from-given-supplies
2221-check-if-a-parentheses-string-can-be-valid
2237-longest-palindrome-by-concatenating-two-letter-words
2463-minimum-recolors-to-get-k-consecutive-black-blocks
2520-using-a-robot-to-print-the-lexicographically-smallest-string
3360-minimum-deletions-to-make-string-k-special
3445-lexicographically-minimum-string-after-removing-stars
3455-minimum-length-of-string-after-operations
3569-count-of-substrings-containing-every-vowel-and-k-consonants-ii
3629-total-characters-in-string-after-transformations-i
3683-find-the-lexicographically-largest-string-from-the-box-i
3872-find-most-frequent-vowel-and-consonant

Math

0002-add-two-numbers
0013-roman-to-integer
0048-rotate-image
0062-unique-paths
0067-add-binary
0070-climbing-stairs
0168-excel-sheet-column-title
0171-excel-sheet-column-number
0189-rotate-array
0202-happy-number
0268-missing-number
0556-next-greater-element-iii
1013-fibonacci-number
1370-count-number-of-nice-subarrays
1411-convert-binary-number-in-a-linked-list-to-integer
1610-xor-operation-in-an-array
1636-number-of-substrings-with-only-1s
1642-water-bottles
1693-sum-of-all-odd-length-subarrays
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
2160-minimum-operations-to-make-a-uni-value-grid
2206-detonate-the-maximum-bombs
2610-closest-prime-numbers-in-range
2645-pass-the-pillow
2649-count-total-number-of-colored-cells
3001-apply-operations-to-maximize-score
3172-divisible-and-non-divisible-sums-difference
3201-distribute-candies-among-children-ii
3227-find-missing-and-repeated-values
3629-total-characters-in-string-after-transformations-i
3830-find-closest-person

Dynamic Programming

0010-regular-expression-matching
0042-trapping-rain-water
0053-maximum-subarray
0062-unique-paths
0070-climbing-stairs
0118-pascals-triangle
0121-best-time-to-buy-and-sell-stock
0122-best-time-to-buy-and-sell-stock-ii
0152-maximum-product-subarray
0542-01-matrix
0954-maximum-sum-circular-subarray
1013-fibonacci-number
2028-the-earliest-and-latest-rounds-where-players-compete
2090-number-of-ways-to-arrive-at-destination
3491-find-the-maximum-length-of-valid-subsequence-ii
3629-total-characters-in-string-after-transformations-i

Recursion

0002-add-two-numbers
0010-regular-expression-matching
0021-merge-two-sorted-lists
0203-remove-linked-list-elements
1013-fibonacci-number
1951-find-the-winner-of-the-circular-game

Memoization

0070-climbing-stairs
1013-fibonacci-number
2028-the-earliest-and-latest-rounds-where-players-compete

Array

0001-two-sum
0004-median-of-two-sorted-arrays
0011-container-with-most-water
0015-3sum
0018-4sum
0026-remove-duplicates-from-sorted-array
0027-remove-element
0031-next-permutation
0033-search-in-rotated-sorted-array
0034-find-first-and-last-position-of-element-in-sorted-array
0035-search-insert-position
0042-trapping-rain-water
0048-rotate-image
0053-maximum-subarray
0054-spiral-matrix
0056-merge-intervals
0073-set-matrix-zeroes
0075-sort-colors
0081-search-in-rotated-sorted-array-ii
0088-merge-sorted-array
0118-pascals-triangle
0121-best-time-to-buy-and-sell-stock
0122-best-time-to-buy-and-sell-stock-ii
0128-longest-consecutive-sequence
0130-surrounded-regions
0134-gas-station
0135-candy
0152-maximum-product-subarray
0153-find-minimum-in-rotated-sorted-array
0167-two-sum-ii-input-array-is-sorted
0169-majority-element
0189-rotate-array
0217-contains-duplicate
0229-majority-element-ii
0238-product-of-array-except-self
0268-missing-number
0283-move-zeroes
0287-find-the-duplicate-number
0303-range-sum-query-immutable
0349-intersection-of-two-arrays
0485-max-consecutive-ones
0496-next-greater-element-i
0503-next-greater-element-ii
0525-contiguous-array
0542-01-matrix
0560-subarray-sum-equals-k
0724-find-pivot-index
0733-flood-fill
0792-binary-search
0940-fruit-into-baskets
0952-word-subsets
0954-maximum-sum-circular-subarray
0966-binary-subarrays-with-sum
1006-vowel-spellchecker
1036-rotting-oranges
1046-max-consecutive-ones-iii
1073-number-of-enclaves
1184-car-pooling
1207-delete-nodes-and-return-forest
1335-maximum-candies-allocated-to-k-children
1370-count-number-of-nice-subarrays
1496-lucky-numbers-in-a-matrix
1514-minimum-value-to-get-positive-step-by-step-sum
1538-maximum-points-you-can-obtain-from-cards
1693-sum-of-all-odd-length-subarrays
1711-find-valid-matrix-given-row-and-column-sums
1720-crawler-log-folder
1803-average-waiting-time
1813-maximum-erasure-value
1833-find-the-highest-altitude
1878-check-if-array-is-sorted-and-rotated
1951-find-the-winner-of-the-circular-game
2160-minimum-operations-to-make-a-uni-value-grid
2206-detonate-the-maximum-bombs
2215-finding-3-digit-even-numbers
2220-find-all-possible-recipes-from-given-supplies
2237-longest-palindrome-by-concatenating-two-letter-words
2265-partition-array-according-to-given-pivot
2271-rearrange-array-elements-by-sign
2306-create-binary-tree-from-descriptions
2308-divide-array-into-equal-pairs
2472-build-a-matrix-with-conditions
2478-longest-nice-subarray
2497-maximum-matching-of-players-with-trainers
2498-smallest-subarrays-with-maximum-bitwise-or
2551-apply-operations-to-an-array
2552-maximum-sum-of-distinct-subarrays-with-length-k
2588-maximum-number-of-points-from-grid-queries
2614-maximum-count-of-positive-integer-and-negative-integer
2626-count-the-number-of-good-subarrays
2665-minimum-time-to-repair-cars
2681-put-marbles-in-bags
2690-house-robber-iv
2707-merge-two-2d-arrays-by-summing-values
2766-find-the-prefix-common-array-of-two-arrays
2846-robot-collisions
2856-count-complete-subarrays-in-an-array
2888-minimum-index-of-a-valid-split
3001-apply-operations-to-maximize-score
3227-find-missing-and-repeated-values
3348-minimum-cost-walk-in-weighted-graph
3430-count-days-without-meetings
3475-minimum-operations-to-make-binary-array-elements-equal-to-one-i
3483-alternating-groups-ii
3491-find-the-maximum-length-of-valid-subsequence-ii
3612-adjacent-increasing-subarrays-detection-i
3639-zero-array-transformation-i
3643-zero-array-transformation-ii
3657-check-if-grid-can-be-cut-into-sections
3747-maximum-difference-between-adjacent-elements-in-a-circular-array

Queue

0225-implement-stack-using-queues
0232-implement-queue-using-stacks
0387-first-unique-character-in-a-string
0954-maximum-sum-circular-subarray
1951-find-the-winner-of-the-circular-game
3475-minimum-operations-to-make-binary-array-elements-equal-to-one-i

Stack

0020-valid-parentheses
0042-trapping-rain-water
0155-min-stack
0225-implement-stack-using-queues
0232-implement-queue-using-stacks
0496-next-greater-element-i
0503-next-greater-element-ii
0726-number-of-atoms
1298-reverse-substrings-between-each-pair-of-parentheses
1720-crawler-log-folder
1818-maximum-score-from-removing-substrings
2128-reverse-prefix-of-word
2221-check-if-a-parentheses-string-can-be-valid
2520-using-a-robot-to-print-the-lexicographically-smallest-string
2846-robot-collisions
3001-apply-operations-to-maximize-score
3445-lexicographically-minimum-string-after-removing-stars

Greedy

0011-container-with-most-water
0122-best-time-to-buy-and-sell-stock-ii
0134-gas-station
0135-candy
0768-partition-labels
1502-construct-k-palindrome-strings
1711-find-valid-matrix-given-row-and-column-sums
1818-maximum-score-from-removing-substrings
2221-check-if-a-parentheses-string-can-be-valid
2237-longest-palindrome-by-concatenating-two-letter-words
2497-maximum-matching-of-players-with-trainers
2509-minimize-xor
2520-using-a-robot-to-print-the-lexicographically-smallest-string
2681-put-marbles-in-bags
3001-apply-operations-to-maximize-score
3360-minimum-deletions-to-make-string-k-special
3445-lexicographically-minimum-string-after-removing-stars

Sorting

0015-3sum
0018-4sum
0056-merge-intervals
0075-sort-colors
0088-merge-sorted-array
0169-majority-element
0217-contains-duplicate
0229-majority-element-ii
0242-valid-anagram
0268-missing-number
0349-intersection-of-two-arrays
0389-find-the-difference
0726-number-of-atoms
1184-car-pooling
2160-minimum-operations-to-make-a-uni-value-grid
2215-finding-3-digit-even-numbers
2497-maximum-matching-of-players-with-trainers
2588-maximum-number-of-points-from-grid-queries
2681-put-marbles-in-bags
2846-robot-collisions
2888-minimum-index-of-a-valid-split
3001-apply-operations-to-maximize-score
3360-minimum-deletions-to-make-string-k-special
3430-count-days-without-meetings
3657-check-if-grid-can-be-cut-into-sections

Hash Table

0001-two-sum
0003-longest-substring-without-repeating-characters
0013-roman-to-integer
0073-set-matrix-zeroes
0127-word-ladder
0128-longest-consecutive-sequence
0141-linked-list-cycle
0160-intersection-of-two-linked-lists
0169-majority-element
0202-happy-number
0217-contains-duplicate
0229-majority-element-ii
0242-valid-anagram
0268-missing-number
0349-intersection-of-two-arrays
0387-first-unique-character-in-a-string
0389-find-the-difference
0424-longest-repeating-character-replacement
0496-next-greater-element-i
0525-contiguous-array
0560-subarray-sum-equals-k
0726-number-of-atoms
0768-partition-labels
0940-fruit-into-baskets
0952-word-subsets
0966-binary-subarrays-with-sum
1006-vowel-spellchecker
1207-delete-nodes-and-return-forest
1370-count-number-of-nice-subarrays
1460-number-of-substrings-containing-all-three-characters
1502-construct-k-palindrome-strings
1813-maximum-erasure-value
2215-finding-3-digit-even-numbers
2220-find-all-possible-recipes-from-given-supplies
2237-longest-palindrome-by-concatenating-two-letter-words
2306-create-binary-tree-from-descriptions
2308-divide-array-into-equal-pairs
2520-using-a-robot-to-print-the-lexicographically-smallest-string
2552-maximum-sum-of-distinct-subarrays-with-length-k
2626-count-the-number-of-good-subarrays
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
3227-find-missing-and-repeated-values
3360-minimum-deletions-to-make-string-k-special
3445-lexicographically-minimum-string-after-removing-stars
3455-minimum-length-of-string-after-operations
3569-count-of-substrings-containing-every-vowel-and-k-consonants-ii
3629-total-characters-in-string-after-transformations-i
3872-find-most-frequent-vowel-and-consonant

Tree

0100-same-tree
0101-symmetric-tree
0104-maximum-depth-of-binary-tree
1207-delete-nodes-and-return-forest
1653-number-of-good-leaf-nodes-pairs
2306-create-binary-tree-from-descriptions
3633-maximize-the-number-of-target-nodes-after-connecting-trees-i

Binary Tree

0100-same-tree
0101-symmetric-tree
0104-maximum-depth-of-binary-tree
1207-delete-nodes-and-return-forest
1653-number-of-good-leaf-nodes-pairs
2306-create-binary-tree-from-descriptions

Depth-First Search

0100-same-tree
0101-symmetric-tree
0104-maximum-depth-of-binary-tree
0130-surrounded-regions
0547-number-of-provinces
0733-flood-fill
0801-is-graph-bipartite
0813-all-paths-from-source-to-target
1073-number-of-enclaves
1207-delete-nodes-and-return-forest
1653-number-of-good-leaf-nodes-pairs
2206-detonate-the-maximum-bombs
2438-find-closest-node-to-given-two-nodes
2793-count-the-number-of-complete-components
3633-maximize-the-number-of-target-nodes-after-connecting-trees-i

Matrix

0048-rotate-image
0054-spiral-matrix
0073-set-matrix-zeroes
0130-surrounded-regions
0542-01-matrix
0733-flood-fill
1036-rotting-oranges
1073-number-of-enclaves
1496-lucky-numbers-in-a-matrix
1711-find-valid-matrix-given-row-and-column-sums
2160-minimum-operations-to-make-a-uni-value-grid
2472-build-a-matrix-with-conditions
2588-maximum-number-of-points-from-grid-queries
3227-find-missing-and-repeated-values

Graph

0547-number-of-provinces
0801-is-graph-bipartite
0813-all-paths-from-source-to-target
2090-number-of-ways-to-arrive-at-destination
2206-detonate-the-maximum-bombs
2220-find-all-possible-recipes-from-given-supplies
2438-find-closest-node-to-given-two-nodes
2472-build-a-matrix-with-conditions
2793-count-the-number-of-complete-components
3348-minimum-cost-walk-in-weighted-graph

Topological Sort

2090-number-of-ways-to-arrive-at-destination
2220-find-all-possible-recipes-from-given-supplies
2472-build-a-matrix-with-conditions

Breadth-First Search

0100-same-tree
0101-symmetric-tree
0104-maximum-depth-of-binary-tree
0127-word-ladder
0130-surrounded-regions
0542-01-matrix
0547-number-of-provinces
0733-flood-fill
0801-is-graph-bipartite
0813-all-paths-from-source-to-target
1036-rotting-oranges
1073-number-of-enclaves
2206-detonate-the-maximum-bombs
2588-maximum-number-of-points-from-grid-queries
2793-count-the-number-of-complete-components
3633-maximize-the-number-of-target-nodes-after-connecting-trees-i

Divide and Conquer

0004-median-of-two-sorted-arrays
0053-maximum-subarray
0169-majority-element
0954-maximum-sum-circular-subarray

Counting

0169-majority-element
0229-majority-element-ii
0387-first-unique-character-in-a-string
1502-construct-k-palindrome-strings
2237-longest-palindrome-by-concatenating-two-letter-words
2308-divide-array-into-equal-pairs
2614-maximum-count-of-positive-integer-and-negative-integer
3360-minimum-deletions-to-make-string-k-special
3455-minimum-length-of-string-after-operations
3629-total-characters-in-string-after-transformations-i
3872-find-most-frequent-vowel-and-consonant

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
0081-search-in-rotated-sorted-array-ii
0153-find-minimum-in-rotated-sorted-array
0167-two-sum-ii-input-array-is-sorted
0268-missing-number
0287-find-the-duplicate-number
0349-intersection-of-two-arrays
0792-binary-search
1046-max-consecutive-ones-iii
1335-maximum-candies-allocated-to-k-children
2498-smallest-subarrays-with-maximum-bitwise-or
2614-maximum-count-of-positive-integer-and-negative-integer
2665-minimum-time-to-repair-cars
2690-house-robber-iv
3643-zero-array-transformation-ii

Bit Manipulation

0067-add-binary
0268-missing-number
0287-find-the-duplicate-number
0389-find-the-difference
1610-xor-operation-in-an-array
2308-divide-array-into-equal-pairs
2478-longest-nice-subarray
2498-smallest-subarrays-with-maximum-bitwise-or
2509-minimize-xor
2766-find-the-prefix-common-array-of-two-arrays
3348-minimum-cost-walk-in-weighted-graph
3475-minimum-operations-to-make-binary-array-elements-equal-to-one-i

Union Find

0128-longest-consecutive-sequence
0130-surrounded-regions
0547-number-of-provinces
0801-is-graph-bipartite
1058-lexicographically-smallest-equivalent-string
1073-number-of-enclaves
2588-maximum-number-of-points-from-grid-queries
2793-count-the-number-of-complete-components
3348-minimum-cost-walk-in-weighted-graph

Prefix Sum

0238-product-of-array-except-self
0303-range-sum-query-immutable
0525-contiguous-array
0560-subarray-sum-equals-k
0724-find-pivot-index
0966-binary-subarrays-with-sum
1046-max-consecutive-ones-iii
1184-car-pooling
1370-count-number-of-nice-subarrays
1514-minimum-value-to-get-positive-step-by-step-sum
1537-maximum-score-after-splitting-a-string
1538-maximum-points-you-can-obtain-from-cards
1693-sum-of-all-odd-length-subarrays
1833-find-the-highest-altitude
3475-minimum-operations-to-make-binary-array-elements-equal-to-one-i
3639-zero-array-transformation-i
3643-zero-array-transformation-ii

Number Theory

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

Sliding Window

0003-longest-substring-without-repeating-characters
0424-longest-repeating-character-replacement
0940-fruit-into-baskets
0966-binary-subarrays-with-sum
1046-max-consecutive-ones-iii
1370-count-number-of-nice-subarrays
1460-number-of-substrings-containing-all-three-characters
1538-maximum-points-you-can-obtain-from-cards
1813-maximum-erasure-value
2463-minimum-recolors-to-get-k-consecutive-black-blocks
2478-longest-nice-subarray
2498-smallest-subarrays-with-maximum-bitwise-or
2552-maximum-sum-of-distinct-subarrays-with-length-k
2626-count-the-number-of-good-subarrays
2856-count-complete-subarrays-in-an-array
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

Shortest Path

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

Heap (Priority Queue)

1184-car-pooling
2588-maximum-number-of-points-from-grid-queries
2681-put-marbles-in-bags
3445-lexicographically-minimum-string-after-removing-stars

Monotonic Stack

0042-trapping-rain-water
0496-next-greater-element-i
0503-next-greater-element-ii
3001-apply-operations-to-maximize-score

Enumeration

2215-finding-3-digit-even-numbers
3201-distribute-candies-among-children-ii
3683-find-the-lexicographically-largest-string-from-the-box-i

Design

0155-min-stack
0225-implement-stack-using-queues
0232-implement-queue-using-stacks
0303-range-sum-query-immutable

Database

0196-delete-duplicate-emails
0197-rising-temperature
0577-employee-bonus
0584-find-customer-referee
0595-big-countries
0596-classes-more-than-5-students
0610-triangle-judgement
0619-biggest-single-number
0620-not-boring-movies
1153-product-sales-analysis-i
1161-project-employees-i
1245-user-activity-for-the-past-30-days-i
1258-article-views-i
1338-queries-quality-and-percentage
1390-average-selling-price
1415-students-and-examinations
1462-list-the-products-ordered-in-a-period
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
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
2127-employees-whose-manager-left-the-company
2495-number-of-unique-subjects-taught-by-each-teacher

String Matching

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

Combinatorics

0062-unique-paths
3201-distribute-candies-among-children-ii

Monotonic Queue

0954-maximum-sum-circular-subarray

Backtracking

0813-all-paths-from-source-to-target

Geometry

2206-detonate-the-maximum-bombs