LeetCode

~Leetcode Solutions

LeetCode Topics

Array

0001-two-sum
0004-median-of-two-sorted-arrays
0014-longest-common-prefix
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
0039-combination-sum
0040-combination-sum-ii
0042-trapping-rain-water
0045-jump-game-ii
0046-permutations
0048-rotate-image
0053-maximum-subarray
0055-jump-game
0056-merge-intervals
0057-insert-interval
0063-unique-paths-ii
0064-minimum-path-sum
0073-set-matrix-zeroes
0074-search-a-2d-matrix
0078-subsets
0084-largest-rectangle-in-histogram
0085-maximal-rectangle
0090-subsets-ii
0105-construct-binary-tree-from-preorder-and-inorder-traversal
0120-triangle
0122-best-time-to-buy-and-sell-stock-ii
0123-best-time-to-buy-and-sell-stock-iii
0130-surrounded-regions
0135-candy
0136-single-number
0188-best-time-to-buy-and-sell-stock-iv
0198-house-robber
0200-number-of-islands
0204-count-primes
0213-house-robber-ii
0215-kth-largest-element-in-an-array
0216-combination-sum-iii
0229-majority-element-ii
0239-sliding-window-maximum
0240-search-a-2d-matrix-ii
0309-best-time-to-buy-and-sell-stock-with-cooldown
0322-coin-change
0410-split-array-largest-sum
0416-partition-equal-subset-sum
0455-assign-cookies
0493-reverse-pairs
0496-next-greater-element-i
0540-single-element-in-a-sorted-array
0542-01-matrix
0560-subarray-sum-equals-k
0713-subarray-product-less-than-k
0714-best-time-to-buy-and-sell-stock-with-transaction-fee
0733-flood-fill
0735-asteroid-collision
0821-shortest-distance-to-a-character
0853-car-fleet
0890-lemonade-change
0907-koko-eating-bananas
0931-minimum-falling-path-sum
0943-sum-of-subarray-minimums
0966-binary-subarrays-with-sum
0967-minimum-falling-path-sum
1034-subarrays-with-k-different-integers
1036-rotting-oranges
1046-max-consecutive-ones-iii
1049-last-stone-weight-ii
1050-construct-binary-search-tree-from-preorder-traversal
1056-capacity-to-ship-packages-within-d-days
1073-number-of-enclaves
1171-shortest-path-in-binary-matrix
1293-three-consecutive-odds
1370-count-number-of-nice-subarrays
1408-find-the-smallest-divisor-given-a-threshold
1510-find-lucky-integer-in-an-array
1538-maximum-points-you-can-obtain-from-cards
1559-cherry-pickup-ii
1605-minimum-number-of-days-to-make-m-bouquets
1628-count-submatrices-with-all-ones
1646-kth-missing-positive-number
1663-detect-cycles-in-2d-grid
1753-path-with-minimum-effort
1913-maximum-product-difference-between-two-pairs
1993-sum-of-all-subset-xor-totals
2022-convert-1d-array-into-2d-array
2227-sum-of-subarray-ranges
2248-intersection-of-multiple-arrays
2277-count-equal-and-divisible-pairs-in-an-array
2284-sender-with-largest-word-count
2394-count-subarrays-with-score-less-than-k
2527-count-subarrays-with-fixed-bounds
2856-count-complete-subarrays-in-an-array
3143-longest-unequal-adjacent-groups-subsequence-i
3461-find-the-minimum-area-to-cover-all-ones-i
3483-alternating-groups-ii
3621-minimum-operations-to-make-array-values-equal-to-k
3622-maximum-frequency-of-an-element-after-performing-operations-i
3639-zero-array-transformation-i
3656-minimum-number-of-operations-to-make-elements-in-array-distinct

Hash Table

0001-two-sum
0003-longest-substring-without-repeating-characters
0013-roman-to-integer
0073-set-matrix-zeroes
0076-minimum-window-substring
0105-construct-binary-tree-from-preorder-and-inorder-traversal
0141-linked-list-cycle
0142-linked-list-cycle-ii
0146-lru-cache
0160-intersection-of-two-linked-lists
0205-isomorphic-strings
0208-implement-trie-prefix-tree
0229-majority-element-ii
0242-valid-anagram
0424-longest-repeating-character-replacement
0451-sort-characters-by-frequency
0496-next-greater-element-i
0560-subarray-sum-equals-k
0653-two-sum-iv-input-is-a-bst
0966-binary-subarrays-with-sum
0984-most-stones-removed-with-same-row-or-column
1034-subarrays-with-k-different-integers
1370-count-number-of-nice-subarrays
1460-number-of-substrings-containing-all-three-characters
1510-find-lucky-integer-in-an-array
1890-sum-of-beauty-of-all-substrings
2248-intersection-of-multiple-arrays
2284-sender-with-largest-word-count
2325-decode-the-message
2856-count-complete-subarrays-in-an-array
3621-minimum-operations-to-make-array-values-equal-to-k
3656-minimum-number-of-operations-to-make-elements-in-array-distinct

Math

0002-add-two-numbers
0007-reverse-integer
0009-palindrome-number
0013-roman-to-integer
0048-rotate-image
0050-powx-n
0070-climbing-stairs
0172-factorial-trailing-zeroes
0204-count-primes
0795-k-th-symbol-in-grammar
1370-count-number-of-nice-subarrays
1993-sum-of-all-subset-xor-totals
2032-largest-odd-number-in-string
2610-closest-prime-numbers-in-range
2649-count-total-number-of-colored-cells
2704-maximum-difference-by-remapping-a-digit

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
0074-search-a-2d-matrix
0240-search-a-2d-matrix-ii
0410-split-array-largest-sum
0493-reverse-pairs
0540-single-element-in-a-sorted-array
0713-subarray-product-less-than-k
0907-koko-eating-bananas
1046-max-consecutive-ones-iii
1056-capacity-to-ship-packages-within-d-days
1408-find-the-smallest-divisor-given-a-threshold
1605-minimum-number-of-days-to-make-m-bouquets
1646-kth-missing-positive-number
1753-path-with-minimum-effort
2394-count-subarrays-with-score-less-than-k
3622-maximum-frequency-of-an-element-after-performing-operations-i

String

0003-longest-substring-without-repeating-characters
0005-longest-palindromic-substring
0008-string-to-integer-atoi
0013-roman-to-integer
0014-longest-common-prefix
0020-valid-parentheses
0022-generate-parentheses
0044-wildcard-matching
0058-length-of-last-word
0072-edit-distance
0076-minimum-window-substring
0115-distinct-subsequences
0151-reverse-words-in-a-string
0205-isomorphic-strings
0208-implement-trie-prefix-tree
0242-valid-anagram
0257-binary-tree-paths
0402-remove-k-digits
0424-longest-repeating-character-replacement
0451-sort-characters-by-frequency
0516-longest-palindromic-subsequence
0583-delete-operation-for-two-strings
0678-valid-parenthesis-string
0821-shortest-distance-to-a-character
1078-remove-outermost-parentheses
1170-shortest-common-supersequence
1250-longest-common-subsequence
1437-minimum-insertion-steps-to-make-a-string-palindrome
1460-number-of-substrings-containing-all-three-characters
1737-maximum-nesting-depth-of-the-parentheses
1890-sum-of-beauty-of-all-substrings
2032-largest-odd-number-in-string
2284-sender-with-largest-word-count
2325-decode-the-message
2395-longest-binary-subsequence-less-than-or-equal-to-k
2463-minimum-recolors-to-get-k-consecutive-black-blocks
2887-sort-vowels-in-a-string
3143-longest-unequal-adjacent-groups-subsequence-i

Matrix

0048-rotate-image
0063-unique-paths-ii
0064-minimum-path-sum
0073-set-matrix-zeroes
0074-search-a-2d-matrix
0085-maximal-rectangle
0130-surrounded-regions
0200-number-of-islands
0240-search-a-2d-matrix-ii
0542-01-matrix
0733-flood-fill
0931-minimum-falling-path-sum
0967-minimum-falling-path-sum
1036-rotting-oranges
1073-number-of-enclaves
1171-shortest-path-in-binary-matrix
1559-cherry-pickup-ii
1628-count-submatrices-with-all-ones
1663-detect-cycles-in-2d-grid
1753-path-with-minimum-effort
2022-convert-1d-array-into-2d-array
3461-find-the-minimum-area-to-cover-all-ones-i

Dynamic Programming

0005-longest-palindromic-substring
0022-generate-parentheses
0042-trapping-rain-water
0044-wildcard-matching
0045-jump-game-ii
0053-maximum-subarray
0055-jump-game
0063-unique-paths-ii
0064-minimum-path-sum
0070-climbing-stairs
0072-edit-distance
0085-maximal-rectangle
0115-distinct-subsequences
0120-triangle
0122-best-time-to-buy-and-sell-stock-ii
0123-best-time-to-buy-and-sell-stock-iii
0124-binary-tree-maximum-path-sum
0188-best-time-to-buy-and-sell-stock-iv
0198-house-robber
0213-house-robber-ii
0309-best-time-to-buy-and-sell-stock-with-cooldown
0322-coin-change
0397-integer-replacement
0410-split-array-largest-sum
0416-partition-equal-subset-sum
0516-longest-palindromic-subsequence
0542-01-matrix
0583-delete-operation-for-two-strings
0678-valid-parenthesis-string
0714-best-time-to-buy-and-sell-stock-with-transaction-fee
0803-cheapest-flights-within-k-stops
0931-minimum-falling-path-sum
0943-sum-of-subarray-minimums
0967-minimum-falling-path-sum
1049-last-stone-weight-ii
1170-shortest-common-supersequence
1250-longest-common-subsequence
1437-minimum-insertion-steps-to-make-a-string-palindrome
1559-cherry-pickup-ii
1628-count-submatrices-with-all-ones
2395-longest-binary-subsequence-less-than-or-equal-to-k
3143-longest-unequal-adjacent-groups-subsequence-i

Greedy

0044-wildcard-matching
0045-jump-game-ii
0055-jump-game
0122-best-time-to-buy-and-sell-stock-ii
0135-candy
0397-integer-replacement
0402-remove-k-digits
0410-split-array-largest-sum
0455-assign-cookies
0678-valid-parenthesis-string
0714-best-time-to-buy-and-sell-stock-with-transaction-fee
0890-lemonade-change
2032-largest-odd-number-in-string
2395-longest-binary-subsequence-less-than-or-equal-to-k
2704-maximum-difference-by-remapping-a-digit
3143-longest-unequal-adjacent-groups-subsequence-i

Prefix Sum

0410-split-array-largest-sum
0560-subarray-sum-equals-k
0713-subarray-product-less-than-k
0966-binary-subarrays-with-sum
1046-max-consecutive-ones-iii
1370-count-number-of-nice-subarrays
1538-maximum-points-you-can-obtain-from-cards
2394-count-subarrays-with-score-less-than-k
3622-maximum-frequency-of-an-element-after-performing-operations-i
3639-zero-array-transformation-i

Divide and Conquer

0004-median-of-two-sorted-arrays
0053-maximum-subarray
0105-construct-binary-tree-from-preorder-and-inorder-traversal
0215-kth-largest-element-in-an-array
0240-search-a-2d-matrix-ii
0493-reverse-pairs

Stack

0020-valid-parentheses
0042-trapping-rain-water
0084-largest-rectangle-in-histogram
0085-maximal-rectangle
0094-binary-tree-inorder-traversal
0144-binary-tree-preorder-traversal
0145-binary-tree-postorder-traversal
0155-min-stack
0225-implement-stack-using-queues
0232-implement-queue-using-stacks
0234-palindrome-linked-list
0402-remove-k-digits
0496-next-greater-element-i
0678-valid-parenthesis-string
0735-asteroid-collision
0853-car-fleet
0937-online-stock-span
0943-sum-of-subarray-minimums
1050-construct-binary-search-tree-from-preorder-traversal
1078-remove-outermost-parentheses
1628-count-submatrices-with-all-ones
1737-maximum-nesting-depth-of-the-parentheses
2227-sum-of-subarray-ranges

Two Pointers

0005-longest-palindromic-substring
0018-4sum
0019-remove-nth-node-from-end-of-list
0026-remove-duplicates-from-sorted-array
0027-remove-element
0031-next-permutation
0042-trapping-rain-water
0061-rotate-list
0141-linked-list-cycle
0142-linked-list-cycle-ii
0151-reverse-words-in-a-string
0160-intersection-of-two-linked-lists
0234-palindrome-linked-list
0295-find-median-from-data-stream
0455-assign-cookies
0653-two-sum-iv-input-is-a-bst
0821-shortest-distance-to-a-character
0876-middle-of-the-linked-list
0908-middle-of-the-linked-list

Trie

0014-longest-common-prefix
0208-implement-trie-prefix-tree

Sorting

0018-4sum
0056-merge-intervals
0215-kth-largest-element-in-an-array
0229-majority-element-ii
0242-valid-anagram
0295-find-median-from-data-stream
0451-sort-characters-by-frequency
0455-assign-cookies
0853-car-fleet
1913-maximum-product-difference-between-two-pairs
2248-intersection-of-multiple-arrays
2887-sort-vowels-in-a-string
3622-maximum-frequency-of-an-element-after-performing-operations-i

Heap (Priority Queue)

0215-kth-largest-element-in-an-array
0239-sliding-window-maximum
0295-find-median-from-data-stream
0451-sort-characters-by-frequency
0803-cheapest-flights-within-k-stops
1753-path-with-minimum-effort

Bucket Sort

0451-sort-characters-by-frequency

Counting

0229-majority-element-ii
0451-sort-characters-by-frequency
1034-subarrays-with-k-different-integers
1510-find-lucky-integer-in-an-array
1890-sum-of-beauty-of-all-substrings
2248-intersection-of-multiple-arrays
2284-sender-with-largest-word-count

Linked List

0002-add-two-numbers
0019-remove-nth-node-from-end-of-list
0021-merge-two-sorted-lists
0061-rotate-list
0141-linked-list-cycle
0142-linked-list-cycle-ii
0146-lru-cache
0160-intersection-of-two-linked-lists
0206-reverse-linked-list
0234-palindrome-linked-list
0237-delete-node-in-a-linked-list
0876-middle-of-the-linked-list
0908-middle-of-the-linked-list

Recursion

0002-add-two-numbers
0021-merge-two-sorted-lists
0044-wildcard-matching
0050-powx-n
0206-reverse-linked-list
0234-palindrome-linked-list
0795-k-th-symbol-in-grammar

Bit Manipulation

0078-subsets
0090-subsets-ii
0136-single-number
0397-integer-replacement
0795-k-th-symbol-in-grammar
1993-sum-of-all-subset-xor-totals
2323-minimum-bit-flips-to-convert-number

Backtracking

0022-generate-parentheses
0039-combination-sum
0040-combination-sum-ii
0046-permutations
0078-subsets
0090-subsets-ii
0216-combination-sum-iii
0257-binary-tree-paths
1993-sum-of-all-subset-xor-totals

Enumeration

0204-count-primes
1993-sum-of-all-subset-xor-totals

Number Theory

0204-count-primes
2610-closest-prime-numbers-in-range

Design

0146-lru-cache
0155-min-stack
0208-implement-trie-prefix-tree
0225-implement-stack-using-queues
0232-implement-queue-using-stacks
0295-find-median-from-data-stream
0937-online-stock-span

Queue

0225-implement-stack-using-queues
0232-implement-queue-using-stacks
0239-sliding-window-maximum
2527-count-subarrays-with-fixed-bounds

Monotonic Stack

0042-trapping-rain-water
0084-largest-rectangle-in-histogram
0085-maximal-rectangle
0402-remove-k-digits
0496-next-greater-element-i
0853-car-fleet
0937-online-stock-span
0943-sum-of-subarray-minimums
1050-construct-binary-search-tree-from-preorder-traversal
1628-count-submatrices-with-all-ones
2227-sum-of-subarray-ranges

Simulation

0735-asteroid-collision
2022-convert-1d-array-into-2d-array

Sliding Window

0003-longest-substring-without-repeating-characters
0076-minimum-window-substring
0239-sliding-window-maximum
0424-longest-repeating-character-replacement
0713-subarray-product-less-than-k
0966-binary-subarrays-with-sum
1034-subarrays-with-k-different-integers
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
2394-count-subarrays-with-score-less-than-k
2463-minimum-recolors-to-get-k-consecutive-black-blocks
2527-count-subarrays-with-fixed-bounds
2856-count-complete-subarrays-in-an-array
3483-alternating-groups-ii
3622-maximum-frequency-of-an-element-after-performing-operations-i

Monotonic Queue

0239-sliding-window-maximum
2527-count-subarrays-with-fixed-bounds

Data Stream

0295-find-median-from-data-stream
0937-online-stock-span

Tree

0094-binary-tree-inorder-traversal
0098-validate-binary-search-tree
0099-recover-binary-search-tree
0100-same-tree
0101-symmetric-tree
0104-maximum-depth-of-binary-tree
0105-construct-binary-tree-from-preorder-and-inorder-traversal
0110-balanced-binary-tree
0112-path-sum
0124-binary-tree-maximum-path-sum
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
0257-binary-tree-paths
0450-delete-node-in-a-bst
0543-diameter-of-binary-tree
0653-two-sum-iv-input-is-a-bst
0783-search-in-a-binary-search-tree
0784-insert-into-a-binary-search-tree
1050-construct-binary-search-tree-from-preorder-traversal

Depth-First Search

0094-binary-tree-inorder-traversal
0098-validate-binary-search-tree
0099-recover-binary-search-tree
0100-same-tree
0101-symmetric-tree
0104-maximum-depth-of-binary-tree
0110-balanced-binary-tree
0112-path-sum
0124-binary-tree-maximum-path-sum
0130-surrounded-regions
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
0257-binary-tree-paths
0543-diameter-of-binary-tree
0547-number-of-provinces
0653-two-sum-iv-input-is-a-bst
0733-flood-fill
0785-is-graph-bipartite
0801-is-graph-bipartite
0803-cheapest-flights-within-k-stops
0820-find-eventual-safe-states
0984-most-stones-removed-with-same-row-or-column
1073-number-of-enclaves
1442-number-of-operations-to-make-network-connected
1663-detect-cycles-in-2d-grid
1753-path-with-minimum-effort

Binary Tree

0094-binary-tree-inorder-traversal
0098-validate-binary-search-tree
0099-recover-binary-search-tree
0100-same-tree
0101-symmetric-tree
0104-maximum-depth-of-binary-tree
0105-construct-binary-tree-from-preorder-and-inorder-traversal
0110-balanced-binary-tree
0112-path-sum
0124-binary-tree-maximum-path-sum
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
0257-binary-tree-paths
0450-delete-node-in-a-bst
0543-diameter-of-binary-tree
0653-two-sum-iv-input-is-a-bst
0783-search-in-a-binary-search-tree
0784-insert-into-a-binary-search-tree
1050-construct-binary-search-tree-from-preorder-traversal

Breadth-First Search

0100-same-tree
0101-symmetric-tree
0104-maximum-depth-of-binary-tree
0112-path-sum
0130-surrounded-regions
0199-binary-tree-right-side-view
0200-number-of-islands
0207-course-schedule
0210-course-schedule-ii
0226-invert-binary-tree
0322-coin-change
0542-01-matrix
0547-number-of-provinces
0653-two-sum-iv-input-is-a-bst
0733-flood-fill
0785-is-graph-bipartite
0801-is-graph-bipartite
0803-cheapest-flights-within-k-stops
0820-find-eventual-safe-states
1036-rotting-oranges
1073-number-of-enclaves
1171-shortest-path-in-binary-matrix
1442-number-of-operations-to-make-network-connected
1663-detect-cycles-in-2d-grid
1753-path-with-minimum-effort

Binary Search Tree

0098-validate-binary-search-tree
0099-recover-binary-search-tree
0230-kth-smallest-element-in-a-bst
0235-lowest-common-ancestor-of-a-binary-search-tree
0450-delete-node-in-a-bst
0653-two-sum-iv-input-is-a-bst
0783-search-in-a-binary-search-tree
0784-insert-into-a-binary-search-tree
1050-construct-binary-search-tree-from-preorder-traversal

Union Find

0130-surrounded-regions
0200-number-of-islands
0547-number-of-provinces
0801-is-graph-bipartite
0984-most-stones-removed-with-same-row-or-column
1073-number-of-enclaves
1442-number-of-operations-to-make-network-connected
1663-detect-cycles-in-2d-grid
1753-path-with-minimum-effort

Graph

0207-course-schedule
0210-course-schedule-ii
0547-number-of-provinces
0801-is-graph-bipartite
0803-cheapest-flights-within-k-stops
0820-find-eventual-safe-states
0984-most-stones-removed-with-same-row-or-column
1442-number-of-operations-to-make-network-connected

Combinatorics

1993-sum-of-all-subset-xor-totals

Topological Sort

0207-course-schedule
0210-course-schedule-ii
0820-find-eventual-safe-states

Shortest Path

0803-cheapest-flights-within-k-stops

Memoization

0070-climbing-stairs
0397-integer-replacement
2395-longest-binary-subsequence-less-than-or-equal-to-k

Binary Indexed Tree

0493-reverse-pairs

Segment Tree

0493-reverse-pairs

Merge Sort

0493-reverse-pairs

Ordered Set

0493-reverse-pairs

Union-Find

0785-is-graph-bipartite

Graph Theory

0207-course-schedule
0785-is-graph-bipartite

Quickselect

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

Doubly-Linked List

0146-lru-cache