A collection of LeetCode questions to ace the coding interview!

LeetCode Topics

Math

0007-reverse-integer
0009-palindrome-number
0029-divide-two-integers
0048-rotate-image
0062-unique-paths
0070-climbing-stairs
0189-rotate-array
0202-happy-number
0231-power-of-two
0268-missing-number
0273-integer-to-english-words
0412-fizz-buzz
0539-minimum-time-difference
0592-fraction-addition-and-subtraction
0670-maximum-swap
1013-fibonacci-number
2155-find-missing-observations
2645-pass-the-pillow
2716-prime-subtraction-operation
2903-insert-greatest-common-divisors-in-linked-list
3275-minimum-number-of-pushes-to-type-word-i

Simulation

0412-fizz-buzz
0592-fraction-addition-and-subtraction
0874-backspace-string-compare
0898-transpose-matrix
0906-walking-robot-simulation
0921-spiral-matrix-iii
1184-car-pooling
1667-find-kth-bit-in-nth-binary-string
1803-average-waiting-time
2006-find-the-student-that-will-replace-the-chalk
2132-convert-1d-array-into-2d-array
2155-find-missing-observations
2271-rearrange-array-elements-by-sign
2343-count-unguarded-cells-in-the-grid
2411-spiral-matrix-iv
2551-apply-operations-to-an-array
2645-pass-the-pillow
2800-minimum-string-length-after-removing-substrings

Array

0001-two-sum
0011-container-with-most-water
0015-3sum
0026-remove-duplicates-from-sorted-array
0027-remove-element
0031-next-permutation
0036-valid-sudoku
0042-trapping-rain-water
0046-permutations
0048-rotate-image
0049-group-anagrams
0053-maximum-subarray
0056-merge-intervals
0063-unique-paths-ii
0064-minimum-path-sum
0073-set-matrix-zeroes
0074-search-a-2d-matrix
0075-sort-colors
0078-subsets
0080-remove-duplicates-from-sorted-array-ii
0088-merge-sorted-array
0120-triangle
0121-best-time-to-buy-and-sell-stock
0128-longest-consecutive-sequence
0130-surrounded-regions
0136-single-number
0139-word-break
0167-two-sum-ii-input-array-is-sorted
0169-majority-element
0179-largest-number
0189-rotate-array
0198-house-robber
0200-number-of-islands
0209-minimum-size-subarray-sum
0213-house-robber-ii
0215-kth-largest-element-in-an-array
0217-contains-duplicate
0238-product-of-array-except-self
0268-missing-number
0283-move-zeroes
0347-top-k-frequent-elements
0349-intersection-of-two-arrays
0416-partition-equal-subset-sum
0455-assign-cookies
0485-max-consecutive-ones
0496-next-greater-element-i
0503-next-greater-element-ii
0539-minimum-time-difference
0542-01-matrix
0560-subarray-sum-equals-k
0624-maximum-distance-in-arrays
0632-smallest-range-covering-elements-from-k-lists
0729-my-calendar-i
0731-my-calendar-ii
0733-flood-fill
0787-sliding-puzzle
0890-lemonade-change
0898-transpose-matrix
0906-walking-robot-simulation
0921-spiral-matrix-iii
0967-minimum-falling-path-sum
1036-rotting-oranges
1046-max-consecutive-ones-iii
1056-capacity-to-ship-packages-within-d-days
1073-number-of-enclaves
1147-flip-columns-for-maximum-number-of-equal-rows
1184-car-pooling
1256-rank-transform-of-an-array
1421-find-numbers-with-even-number-of-digits
1435-xor-queries-of-a-subarray
1468-check-if-n-and-its-double-exist
1497-design-a-stack-with-increment-operation
1556-make-two-arrays-equal-by-reversing-subarrays
1605-minimum-number-of-days-to-make-m-bouquets
1615-range-sum-of-sorted-subarray-sums
1620-check-if-array-pairs-are-divisible-by-k
1646-kth-missing-positive-number
1679-shortest-subarray-to-be-removed-to-make-array-sorted
1694-make-sum-divisible-by-p
1755-defuse-the-bomb
1786-count-the-number-of-consistent-strings
1803-average-waiting-time
1878-check-if-array-is-sorted-and-rotated
1923-sentence-similarity-iii
2006-find-the-student-that-will-replace-the-chalk
2035-count-sub-islands
2054-the-number-of-the-smallest-unoccupied-chair
2132-convert-1d-array-into-2d-array
2155-find-missing-observations
2163-kth-distinct-string-in-an-array
2170-count-number-of-maximum-bitwise-or-subsets
2188-minimized-maximum-of-products-distributed-to-any-store
2255-minimum-swaps-to-group-all-1s-together-ii
2271-rearrange-array-elements-by-sign
2343-count-unguarded-cells-in-the-grid
2358-number-of-ways-to-split-array
2411-spiral-matrix-iv
2488-divide-intervals-into-minimum-number-of-groups
2503-longest-subarray-with-maximum-bitwise-and
2551-apply-operations-to-an-array
2552-maximum-sum-of-distinct-subarrays-with-length-k
2616-maximal-score-after-applying-k-operations
2699-count-the-number-of-fair-pairs
2716-prime-subtraction-operation
2727-number-of-senior-citizens
3291-find-if-array-can-be-sorted
3329-find-the-length-of-the-longest-common-prefix
3501-delete-nodes-from-linked-list-present-in-array
3522-find-the-power-of-k-size-subarrays-i

Hash Table

0001-two-sum
0003-longest-substring-without-repeating-characters
0036-valid-sudoku
0049-group-anagrams
0073-set-matrix-zeroes
0128-longest-consecutive-sequence
0139-word-break
0141-linked-list-cycle
0169-majority-element
0202-happy-number
0217-contains-duplicate
0242-valid-anagram
0268-missing-number
0347-top-k-frequent-elements
0349-intersection-of-two-arrays
0383-ransom-note
0496-next-greater-element-i
0560-subarray-sum-equals-k
0632-smallest-range-covering-elements-from-k-lists
0906-walking-robot-simulation
0920-uncommon-words-from-two-sentences
1147-flip-columns-for-maximum-number-of-equal-rows
1256-rank-transform-of-an-array
1468-check-if-n-and-its-double-exist
1473-find-the-longest-substring-containing-vowels-in-even-counts
1556-make-two-arrays-equal-by-reversing-subarrays
1620-check-if-array-pairs-are-divisible-by-k
1694-make-sum-divisible-by-p
1715-split-a-string-into-the-max-number-of-unique-substrings
1786-count-the-number-of-consistent-strings
2054-the-number-of-the-smallest-unoccupied-chair
2163-kth-distinct-string-in-an-array
2552-maximum-sum-of-distinct-subarrays-with-length-k
2599-take-k-of-each-character-from-left-and-right
3267-find-longest-special-substring-that-occurs-thrice-i
3276-minimum-number-of-pushes-to-type-word-ii
3329-find-the-length-of-the-longest-common-prefix
3501-delete-nodes-from-linked-list-present-in-array

String

0003-longest-substring-without-repeating-characters
0006-zigzag-conversion
0020-valid-parentheses
0022-generate-parentheses
0049-group-anagrams
0125-valid-palindrome
0139-word-break
0151-reverse-words-in-a-string
0179-largest-number
0242-valid-anagram
0273-integer-to-english-words
0344-reverse-string
0345-reverse-vowels-of-a-string
0383-ransom-note
0412-fizz-buzz
0443-string-compression
0539-minimum-time-difference
0592-fraction-addition-and-subtraction
0680-valid-palindrome-ii
0874-backspace-string-compare
0920-uncommon-words-from-two-sentences
0957-minimum-add-to-make-parentheses-valid
1197-parsing-a-boolean-expression
1304-longest-happy-string
1473-find-the-longest-substring-containing-vowels-in-even-counts
1667-find-kth-bit-in-nth-binary-string
1715-split-a-string-into-the-max-number-of-unique-substrings
1786-count-the-number-of-consistent-strings
1894-merge-strings-alternately
1923-sentence-similarity-iii
2095-minimum-number-of-swaps-to-make-the-string-balanced
2134-maximize-the-confusion-of-an-exam
2163-kth-distinct-string-in-an-array
2599-take-k-of-each-character-from-left-and-right
2727-number-of-senior-citizens
2800-minimum-string-length-after-removing-substrings
3195-separate-black-and-white-balls
3267-find-longest-special-substring-that-occurs-thrice-i
3275-minimum-number-of-pushes-to-type-word-i
3276-minimum-number-of-pushes-to-type-word-ii
3329-find-the-length-of-the-longest-common-prefix
3451-string-compression-iii
3468-find-the-encrypted-string

Sorting

0015-3sum
0049-group-anagrams
0056-merge-intervals
0075-sort-colors
0088-merge-sorted-array
0169-majority-element
0179-largest-number
0215-kth-largest-element-in-an-array
0217-contains-duplicate
0242-valid-anagram
0268-missing-number
0347-top-k-frequent-elements
0349-intersection-of-two-arrays
0455-assign-cookies
0539-minimum-time-difference
0632-smallest-range-covering-elements-from-k-lists
1184-car-pooling
1256-rank-transform-of-an-array
1468-check-if-n-and-its-double-exist
1556-make-two-arrays-equal-by-reversing-subarrays
1615-range-sum-of-sorted-subarray-sums
2488-divide-intervals-into-minimum-number-of-groups
2699-count-the-number-of-fair-pairs
3276-minimum-number-of-pushes-to-type-word-ii
3291-find-if-array-can-be-sorted

Two Pointers

0011-container-with-most-water
0015-3sum
0026-remove-duplicates-from-sorted-array
0027-remove-element
0031-next-permutation
0042-trapping-rain-water
0075-sort-colors
0080-remove-duplicates-from-sorted-array-ii
0088-merge-sorted-array
0125-valid-palindrome
0141-linked-list-cycle
0151-reverse-words-in-a-string
0167-two-sum-ii-input-array-is-sorted
0189-rotate-array
0202-happy-number
0283-move-zeroes
0344-reverse-string
0345-reverse-vowels-of-a-string
0349-intersection-of-two-arrays
0443-string-compression
0455-assign-cookies
0680-valid-palindrome-ii
0874-backspace-string-compare
0908-middle-of-the-linked-list
1468-check-if-n-and-its-double-exist
1615-range-sum-of-sorted-subarray-sums
1679-shortest-subarray-to-be-removed-to-make-array-sorted
1894-merge-strings-alternately
1923-sentence-similarity-iii
2095-minimum-number-of-swaps-to-make-the-string-balanced
2216-delete-the-middle-node-of-a-linked-list
2271-rearrange-array-elements-by-sign
2488-divide-intervals-into-minimum-number-of-groups
2551-apply-operations-to-an-array
2699-count-the-number-of-fair-pairs
3195-separate-black-and-white-balls

Binary Search

0074-search-a-2d-matrix
0167-two-sum-ii-input-array-is-sorted
0209-minimum-size-subarray-sum
0268-missing-number
0349-intersection-of-two-arrays
0729-my-calendar-i
0731-my-calendar-ii
1046-max-consecutive-ones-iii
1056-capacity-to-ship-packages-within-d-days
1468-check-if-n-and-its-double-exist
1605-minimum-number-of-days-to-make-m-bouquets
1615-range-sum-of-sorted-subarray-sums
1646-kth-missing-positive-number
1679-shortest-subarray-to-be-removed-to-make-array-sorted
2006-find-the-student-that-will-replace-the-chalk
2134-maximize-the-confusion-of-an-exam
2188-minimized-maximum-of-products-distributed-to-any-store
2699-count-the-number-of-fair-pairs
2716-prime-subtraction-operation
3267-find-longest-special-substring-that-occurs-thrice-i

Prefix Sum

0209-minimum-size-subarray-sum
0238-product-of-array-except-self
0560-subarray-sum-equals-k
0731-my-calendar-ii
1046-max-consecutive-ones-iii
1184-car-pooling
1435-xor-queries-of-a-subarray
1473-find-the-longest-substring-containing-vowels-in-even-counts
1694-make-sum-divisible-by-p
2006-find-the-student-that-will-replace-the-chalk
2134-maximize-the-confusion-of-an-exam
2358-number-of-ways-to-split-array
2488-divide-intervals-into-minimum-number-of-groups

Greedy

0011-container-with-most-water
0179-largest-number
0455-assign-cookies
0624-maximum-distance-in-arrays
0632-smallest-range-covering-elements-from-k-lists
0670-maximum-swap
0680-valid-palindrome-ii
0890-lemonade-change
0957-minimum-add-to-make-parentheses-valid
1304-longest-happy-string
2095-minimum-number-of-swaps-to-make-the-string-balanced
2488-divide-intervals-into-minimum-number-of-groups
2616-maximal-score-after-applying-k-operations
2716-prime-subtraction-operation
3195-separate-black-and-white-balls
3275-minimum-number-of-pushes-to-type-word-i
3276-minimum-number-of-pushes-to-type-word-ii

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
0874-backspace-string-compare
0957-minimum-add-to-make-parentheses-valid
1197-parsing-a-boolean-expression
1497-design-a-stack-with-increment-operation
1679-shortest-subarray-to-be-removed-to-make-array-sorted
2095-minimum-number-of-swaps-to-make-the-string-balanced
2800-minimum-string-length-after-removing-substrings

Design

0155-min-stack
0225-implement-stack-using-queues
0232-implement-queue-using-stacks
0729-my-calendar-i
0731-my-calendar-ii
1497-design-a-stack-with-increment-operation

Queue

0225-implement-stack-using-queues
0232-implement-queue-using-stacks

Monotonic Stack

0042-trapping-rain-water
0496-next-greater-element-i
0503-next-greater-element-ii
1679-shortest-subarray-to-be-removed-to-make-array-sorted

Sliding Window

0003-longest-substring-without-repeating-characters
0209-minimum-size-subarray-sum
0632-smallest-range-covering-elements-from-k-lists
1046-max-consecutive-ones-iii
1755-defuse-the-bomb
2134-maximize-the-confusion-of-an-exam
2255-minimum-swaps-to-group-all-1s-together-ii
2552-maximum-sum-of-distinct-subarrays-with-length-k
2599-take-k-of-each-character-from-left-and-right
3267-find-longest-special-substring-that-occurs-thrice-i
3522-find-the-power-of-k-size-subarrays-i

Matrix

0036-valid-sudoku
0048-rotate-image
0063-unique-paths-ii
0064-minimum-path-sum
0073-set-matrix-zeroes
0074-search-a-2d-matrix
0130-surrounded-regions
0200-number-of-islands
0542-01-matrix
0733-flood-fill
0787-sliding-puzzle
0898-transpose-matrix
0921-spiral-matrix-iii
0967-minimum-falling-path-sum
1036-rotting-oranges
1073-number-of-enclaves
1147-flip-columns-for-maximum-number-of-equal-rows
2035-count-sub-islands
2132-convert-1d-array-into-2d-array
2343-count-unguarded-cells-in-the-grid
2411-spiral-matrix-iv

Bit Manipulation

0029-divide-two-integers
0078-subsets
0136-single-number
0231-power-of-two
0268-missing-number
0476-number-complement
1435-xor-queries-of-a-subarray
1473-find-the-longest-substring-containing-vowels-in-even-counts
1786-count-the-number-of-consistent-strings
2170-count-number-of-maximum-bitwise-or-subsets
2323-minimum-bit-flips-to-convert-number
2503-longest-subarray-with-maximum-bitwise-and
3291-find-if-array-can-be-sorted

Divide and Conquer

0053-maximum-subarray
0169-majority-element
0215-kth-largest-element-in-an-array
0347-top-k-frequent-elements

Counting

0169-majority-element
0347-top-k-frequent-elements
0383-ransom-note
0920-uncommon-words-from-two-sentences
1620-check-if-array-pairs-are-divisible-by-k
1786-count-the-number-of-consistent-strings
2163-kth-distinct-string-in-an-array
3267-find-longest-special-substring-that-occurs-thrice-i
3276-minimum-number-of-pushes-to-type-word-ii

Dynamic Programming

0022-generate-parentheses
0042-trapping-rain-water
0053-maximum-subarray
0062-unique-paths
0063-unique-paths-ii
0064-minimum-path-sum
0070-climbing-stairs
0120-triangle
0121-best-time-to-buy-and-sell-stock
0139-word-break
0198-house-robber
0213-house-robber-ii
0416-partition-equal-subset-sum
0542-01-matrix
0967-minimum-falling-path-sum
1013-fibonacci-number

Union Find

0128-longest-consecutive-sequence
0130-surrounded-regions
0200-number-of-islands
0547-number-of-provinces
0801-is-graph-bipartite
1073-number-of-enclaves
2035-count-sub-islands

Recursion

0021-merge-two-sorted-lists
0206-reverse-linked-list
0231-power-of-two
0273-integer-to-english-words
1013-fibonacci-number
1197-parsing-a-boolean-expression
1667-find-kth-bit-in-nth-binary-string

Memoization

0070-climbing-stairs
0139-word-break
1013-fibonacci-number

Backtracking

0022-generate-parentheses
0046-permutations
0078-subsets
1715-split-a-string-into-the-max-number-of-unique-substrings
2170-count-number-of-maximum-bitwise-or-subsets

Depth-First Search

0100-same-tree
0104-maximum-depth-of-binary-tree
0130-surrounded-regions
0199-binary-tree-right-side-view
0200-number-of-islands
0226-invert-binary-tree
0386-lexicographical-numbers
0547-number-of-provinces
0637-average-of-levels-in-binary-tree
0733-flood-fill
0801-is-graph-bipartite
0820-find-eventual-safe-states
1073-number-of-enclaves
1484-linked-list-in-binary-tree
2035-count-sub-islands

Breadth-First Search

0100-same-tree
0102-binary-tree-level-order-traversal
0103-binary-tree-zigzag-level-order-traversal
0104-maximum-depth-of-binary-tree
0130-surrounded-regions
0199-binary-tree-right-side-view
0200-number-of-islands
0226-invert-binary-tree
0542-01-matrix
0547-number-of-provinces
0637-average-of-levels-in-binary-tree
0733-flood-fill
0787-sliding-puzzle
0801-is-graph-bipartite
0820-find-eventual-safe-states
1036-rotting-oranges
1073-number-of-enclaves
1484-linked-list-in-binary-tree
2035-count-sub-islands

Graph

0547-number-of-provinces
0801-is-graph-bipartite
0820-find-eventual-safe-states
1916-find-center-of-star-graph
3189-find-champion-ii

Topological Sort

0820-find-eventual-safe-states

Linked List

0021-merge-two-sorted-lists
0141-linked-list-cycle
0206-reverse-linked-list
0237-delete-node-in-a-linked-list
0328-odd-even-linked-list
0725-split-linked-list-in-parts
0908-middle-of-the-linked-list
1484-linked-list-in-binary-tree
2216-delete-the-middle-node-of-a-linked-list
2411-spiral-matrix-iv
2903-insert-greatest-common-divisors-in-linked-list
3501-delete-nodes-from-linked-list-present-in-array

Tree

0100-same-tree
0102-binary-tree-level-order-traversal
0103-binary-tree-zigzag-level-order-traversal
0104-maximum-depth-of-binary-tree
0199-binary-tree-right-side-view
0226-invert-binary-tree
0637-average-of-levels-in-binary-tree
1484-linked-list-in-binary-tree

Binary Tree

0100-same-tree
0102-binary-tree-level-order-traversal
0103-binary-tree-zigzag-level-order-traversal
0104-maximum-depth-of-binary-tree
0199-binary-tree-right-side-view
0226-invert-binary-tree
0637-average-of-levels-in-binary-tree
1484-linked-list-in-binary-tree

Number Theory

2716-prime-subtraction-operation
2903-insert-greatest-common-divisors-in-linked-list

Brainteaser

2503-longest-subarray-with-maximum-bitwise-and

Trie

0139-word-break
0386-lexicographical-numbers
3329-find-the-length-of-the-longest-common-prefix

Segment Tree

0729-my-calendar-i
0731-my-calendar-ii

Ordered Set

0729-my-calendar-i
0731-my-calendar-ii

Heap (Priority Queue)

0215-kth-largest-element-in-an-array
0347-top-k-frequent-elements
0632-smallest-range-covering-elements-from-k-lists
1184-car-pooling
1304-longest-happy-string
2054-the-number-of-the-smallest-unoccupied-chair
2488-divide-intervals-into-minimum-number-of-groups
2616-maximal-score-after-applying-k-operations

Enumeration

2170-count-number-of-maximum-bitwise-or-subsets

Combinatorics

0062-unique-paths

Bucket Sort

0347-top-k-frequent-elements

Quickselect

0215-kth-largest-element-in-an-array
0347-top-k-frequent-elements