LeetCode Topics

Array

0001-two-sum
0004-median-of-two-sorted-arrays
0015-3sum
0018-4sum
0026-remove-duplicates-from-sorted-array
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
0046-permutations
0047-permutations-ii
0048-rotate-image
0053-maximum-subarray
0054-spiral-matrix
0056-merge-intervals
0063-unique-paths-ii
0064-minimum-path-sum
0073-set-matrix-zeroes
0074-search-a-2d-matrix
0075-sort-colors
0079-word-search
0081-search-in-rotated-sorted-array-ii
0084-largest-rectangle-in-histogram
0085-maximal-rectangle
0090-subsets-ii
0105-construct-binary-tree-from-preorder-and-inorder-traversal
0106-construct-binary-tree-from-inorder-and-postorder-traversal
0118-pascals-triangle
0120-triangle
0121-best-time-to-buy-and-sell-stock
0122-best-time-to-buy-and-sell-stock-ii
0123-best-time-to-buy-and-sell-stock-iii
0130-surrounded-regions
0139-word-break
0152-maximum-product-subarray
0153-find-minimum-in-rotated-sorted-array
0154-find-minimum-in-rotated-sorted-array-ii
0162-find-peak-element
0169-majority-element
0188-best-time-to-buy-and-sell-stock-iv
0189-rotate-array
0198-house-robber
0213-house-robber-ii
0216-combination-sum-iii
0229-majority-element-ii
0239-sliding-window-maximum
0240-search-a-2d-matrix-ii
0268-missing-number
0283-move-zeroes
0300-longest-increasing-subsequence
0309-best-time-to-buy-and-sell-stock-with-cooldown
0312-burst-balloons
0322-coin-change
0368-largest-divisible-subset
0416-partition-equal-subset-sum
0421-maximum-xor-of-two-numbers-in-an-array
0485-max-consecutive-ones
0493-reverse-pairs
0494-target-sum
0496-next-greater-element-i
0503-next-greater-element-ii
0518-coin-change-ii
0540-single-element-in-a-sorted-array
0542-01-matrix
0560-subarray-sum-equals-k
0673-number-of-longest-increasing-subsequence
0714-best-time-to-buy-and-sell-stock-with-transaction-fee
0733-flood-fill
0735-asteroid-collision
0792-binary-search
0907-koko-eating-bananas
0940-fruit-into-baskets
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
1050-construct-binary-search-tree-from-preorder-traversal
1056-capacity-to-ship-packages-within-d-days
1073-number-of-enclaves
1121-partition-array-for-maximum-sum
1129-longest-string-chain
1370-count-number-of-nice-subarrays
1402-count-square-submatrices-with-all-ones
1408-find-the-smallest-divisor-given-a-threshold
1538-maximum-points-you-can-obtain-from-cards
1605-minimum-number-of-days-to-make-m-bouquets
1646-kth-missing-positive-number
1669-minimum-cost-to-cut-a-stick
1826-maximum-xor-with-an-element-from-array
1878-check-if-array-is-sorted-and-rotated
2047-find-a-peak-element-ii
2227-sum-of-subarray-ranges
2271-rearrange-array-elements-by-sign

Dynamic Programming

0044-wildcard-matching
0053-maximum-subarray
0062-unique-paths
0063-unique-paths-ii
0064-minimum-path-sum
0070-climbing-stairs
0072-edit-distance
0085-maximal-rectangle
0115-distinct-subsequences
0118-pascals-triangle
0120-triangle
0121-best-time-to-buy-and-sell-stock
0122-best-time-to-buy-and-sell-stock-ii
0123-best-time-to-buy-and-sell-stock-iii
0124-binary-tree-maximum-path-sum
0131-palindrome-partitioning
0132-palindrome-partitioning-ii
0139-word-break
0152-maximum-product-subarray
0188-best-time-to-buy-and-sell-stock-iv
0198-house-robber
0213-house-robber-ii
0300-longest-increasing-subsequence
0309-best-time-to-buy-and-sell-stock-with-cooldown
0312-burst-balloons
0322-coin-change
0368-largest-divisible-subset
0416-partition-equal-subset-sum
0494-target-sum
0516-longest-palindromic-subsequence
0518-coin-change-ii
0542-01-matrix
0583-delete-operation-for-two-strings
0673-number-of-longest-increasing-subsequence
0714-best-time-to-buy-and-sell-stock-with-transaction-fee
0943-sum-of-subarray-minimums
0967-minimum-falling-path-sum
1121-partition-array-for-maximum-sum
1129-longest-string-chain
1170-shortest-common-supersequence
1250-longest-common-subsequence
1402-count-square-submatrices-with-all-ones
1437-minimum-insertion-steps-to-make-a-string-palindrome
1669-minimum-cost-to-cut-a-stick

Math

0048-rotate-image
0050-powx-n
0062-unique-paths
0070-climbing-stairs
0189-rotate-array
0268-missing-number
0368-largest-divisible-subset
1370-count-number-of-nice-subarrays

Combinatorics

0062-unique-paths

Matrix

0048-rotate-image
0054-spiral-matrix
0063-unique-paths-ii
0064-minimum-path-sum
0073-set-matrix-zeroes
0074-search-a-2d-matrix
0079-word-search
0085-maximal-rectangle
0130-surrounded-regions
0240-search-a-2d-matrix-ii
0542-01-matrix
0733-flood-fill
0967-minimum-falling-path-sum
1036-rotting-oranges
1073-number-of-enclaves
1402-count-square-submatrices-with-all-ones
2047-find-a-peak-element-ii

Breadth-First Search

0100-same-tree
0101-symmetric-tree
0102-binary-tree-level-order-traversal
0103-binary-tree-zigzag-level-order-traversal
0104-maximum-depth-of-binary-tree
0127-word-ladder
0130-surrounded-regions
0199-binary-tree-right-side-view
0207-course-schedule
0210-course-schedule-ii
0297-serialize-and-deserialize-binary-tree
0322-coin-change
0542-01-matrix
0547-number-of-provinces
0653-two-sum-iv-input-is-a-bst
0662-maximum-width-of-binary-tree
0733-flood-fill
0801-is-graph-bipartite
0820-find-eventual-safe-states
0893-all-nodes-distance-k-in-binary-tree
1029-vertical-order-traversal-of-a-binary-tree
1036-rotting-oranges
1073-number-of-enclaves

Backtracking

0017-letter-combinations-of-a-phone-number
0039-combination-sum
0040-combination-sum-ii
0046-permutations
0047-permutations-ii
0079-word-search
0090-subsets-ii
0131-palindrome-partitioning
0216-combination-sum-iii
0494-target-sum

String

0003-longest-substring-without-repeating-characters
0017-letter-combinations-of-a-phone-number
0020-valid-parentheses
0044-wildcard-matching
0072-edit-distance
0076-minimum-window-substring
0079-word-search
0115-distinct-subsequences
0127-word-ladder
0131-palindrome-partitioning
0132-palindrome-partitioning-ii
0139-word-break
0208-implement-trie-prefix-tree
0297-serialize-and-deserialize-binary-tree
0402-remove-k-digits
0424-longest-repeating-character-replacement
0516-longest-palindromic-subsequence
0583-delete-operation-for-two-strings
1129-longest-string-chain
1170-shortest-common-supersequence
1197-parsing-a-boolean-expression
1250-longest-common-subsequence
1437-minimum-insertion-steps-to-make-a-string-palindrome
1460-number-of-substrings-containing-all-three-characters

Greedy

0044-wildcard-matching
0122-best-time-to-buy-and-sell-stock-ii
0402-remove-k-digits
0714-best-time-to-buy-and-sell-stock-with-transaction-fee

Recursion

0044-wildcard-matching
0050-powx-n
1197-parsing-a-boolean-expression

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
0081-search-in-rotated-sorted-array-ii
0153-find-minimum-in-rotated-sorted-array
0154-find-minimum-in-rotated-sorted-array-ii
0162-find-peak-element
0222-count-complete-tree-nodes
0240-search-a-2d-matrix-ii
0268-missing-number
0300-longest-increasing-subsequence
0493-reverse-pairs
0540-single-element-in-a-sorted-array
0792-binary-search
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
2047-find-a-peak-element-ii

Sorting

0015-3sum
0018-4sum
0047-permutations-ii
0056-merge-intervals
0075-sort-colors
0169-majority-element
0229-majority-element-ii
0268-missing-number
0368-largest-divisible-subset
1029-vertical-order-traversal-of-a-binary-tree
1129-longest-string-chain
1669-minimum-cost-to-cut-a-stick

Hash Table

0001-two-sum
0003-longest-substring-without-repeating-characters
0017-letter-combinations-of-a-phone-number
0073-set-matrix-zeroes
0076-minimum-window-substring
0105-construct-binary-tree-from-preorder-and-inorder-traversal
0106-construct-binary-tree-from-inorder-and-postorder-traversal
0127-word-ladder
0139-word-break
0146-lru-cache
0169-majority-element
0208-implement-trie-prefix-tree
0229-majority-element-ii
0268-missing-number
0421-maximum-xor-of-two-numbers-in-an-array
0424-longest-repeating-character-replacement
0460-lfu-cache
0496-next-greater-element-i
0560-subarray-sum-equals-k
0653-two-sum-iv-input-is-a-bst
0893-all-nodes-distance-k-in-binary-tree
0940-fruit-into-baskets
0966-binary-subarrays-with-sum
1029-vertical-order-traversal-of-a-binary-tree
1034-subarrays-with-k-different-integers
1129-longest-string-chain
1370-count-number-of-nice-subarrays
1460-number-of-substrings-containing-all-three-characters

Two Pointers

0015-3sum
0018-4sum
0026-remove-duplicates-from-sorted-array
0031-next-permutation
0075-sort-colors
0189-rotate-array
0283-move-zeroes
0653-two-sum-iv-input-is-a-bst
1129-longest-string-chain
2271-rearrange-array-elements-by-sign

Binary Indexed Tree

0493-reverse-pairs
0673-number-of-longest-increasing-subsequence

Segment Tree

0493-reverse-pairs
0673-number-of-longest-increasing-subsequence

Stack

0020-valid-parentheses
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
0173-binary-search-tree-iterator
0225-implement-stack-using-queues
0232-implement-queue-using-stacks
0402-remove-k-digits
0496-next-greater-element-i
0503-next-greater-element-ii
0735-asteroid-collision
0937-online-stock-span
0943-sum-of-subarray-minimums
1050-construct-binary-search-tree-from-preorder-traversal
1197-parsing-a-boolean-expression
2227-sum-of-subarray-ranges

Design

0146-lru-cache
0155-min-stack
0173-binary-search-tree-iterator
0208-implement-trie-prefix-tree
0225-implement-stack-using-queues
0232-implement-queue-using-stacks
0297-serialize-and-deserialize-binary-tree
0460-lfu-cache
0937-online-stock-span

Queue

0225-implement-stack-using-queues
0232-implement-queue-using-stacks
0239-sliding-window-maximum

Monotonic Stack

0084-largest-rectangle-in-histogram
0085-maximal-rectangle
0402-remove-k-digits
0496-next-greater-element-i
0503-next-greater-element-ii
0937-online-stock-span
0943-sum-of-subarray-minimums
1050-construct-binary-search-tree-from-preorder-traversal
2227-sum-of-subarray-ranges

Simulation

0054-spiral-matrix
0735-asteroid-collision
2271-rearrange-array-elements-by-sign

Data Stream

0937-online-stock-span

Sliding Window

0003-longest-substring-without-repeating-characters
0076-minimum-window-substring
0239-sliding-window-maximum
0424-longest-repeating-character-replacement
0940-fruit-into-baskets
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

Heap (Priority Queue)

0239-sliding-window-maximum

Monotonic Queue

0239-sliding-window-maximum

Linked List

0146-lru-cache
0460-lfu-cache

Doubly-Linked List

0146-lru-cache
0460-lfu-cache

Prefix Sum

0560-subarray-sum-equals-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

Counting

0169-majority-element
0229-majority-element-ii
1034-subarrays-with-k-different-integers

Bit Manipulation

0090-subsets-ii
0222-count-complete-tree-nodes
0268-missing-number
0421-maximum-xor-of-two-numbers-in-an-array
1826-maximum-xor-with-an-element-from-array

Divide and Conquer

0004-median-of-two-sorted-arrays
0053-maximum-subarray
0105-construct-binary-tree-from-preorder-and-inorder-traversal
0106-construct-binary-tree-from-inorder-and-postorder-traversal
0169-majority-element
0240-search-a-2d-matrix-ii
0493-reverse-pairs

Merge Sort

0493-reverse-pairs

Ordered Set

0493-reverse-pairs

Tree

0094-binary-tree-inorder-traversal
0098-validate-binary-search-tree
0099-recover-binary-search-tree
0100-same-tree
0101-symmetric-tree
0102-binary-tree-level-order-traversal
0103-binary-tree-zigzag-level-order-traversal
0104-maximum-depth-of-binary-tree
0105-construct-binary-tree-from-preorder-and-inorder-traversal
0106-construct-binary-tree-from-inorder-and-postorder-traversal
0124-binary-tree-maximum-path-sum
0144-binary-tree-preorder-traversal
0145-binary-tree-postorder-traversal
0173-binary-search-tree-iterator
0199-binary-tree-right-side-view
0222-count-complete-tree-nodes
0230-kth-smallest-element-in-a-bst
0235-lowest-common-ancestor-of-a-binary-search-tree
0236-lowest-common-ancestor-of-a-binary-tree
0297-serialize-and-deserialize-binary-tree
0450-delete-node-in-a-bst
0543-diameter-of-binary-tree
0653-two-sum-iv-input-is-a-bst
0662-maximum-width-of-binary-tree
0783-search-in-a-binary-search-tree
0784-insert-into-a-binary-search-tree
0893-all-nodes-distance-k-in-binary-tree
1029-vertical-order-traversal-of-a-binary-tree
1050-construct-binary-search-tree-from-preorder-traversal

Depth-First Search

0079-word-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
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
0207-course-schedule
0210-course-schedule-ii
0230-kth-smallest-element-in-a-bst
0235-lowest-common-ancestor-of-a-binary-search-tree
0236-lowest-common-ancestor-of-a-binary-tree
0297-serialize-and-deserialize-binary-tree
0543-diameter-of-binary-tree
0547-number-of-provinces
0653-two-sum-iv-input-is-a-bst
0662-maximum-width-of-binary-tree
0733-flood-fill
0801-is-graph-bipartite
0820-find-eventual-safe-states
0893-all-nodes-distance-k-in-binary-tree
1029-vertical-order-traversal-of-a-binary-tree
1073-number-of-enclaves

Binary Tree

0094-binary-tree-inorder-traversal
0098-validate-binary-search-tree
0099-recover-binary-search-tree
0100-same-tree
0101-symmetric-tree
0102-binary-tree-level-order-traversal
0103-binary-tree-zigzag-level-order-traversal
0104-maximum-depth-of-binary-tree
0105-construct-binary-tree-from-preorder-and-inorder-traversal
0106-construct-binary-tree-from-inorder-and-postorder-traversal
0124-binary-tree-maximum-path-sum
0144-binary-tree-preorder-traversal
0145-binary-tree-postorder-traversal
0173-binary-search-tree-iterator
0199-binary-tree-right-side-view
0222-count-complete-tree-nodes
0230-kth-smallest-element-in-a-bst
0235-lowest-common-ancestor-of-a-binary-search-tree
0236-lowest-common-ancestor-of-a-binary-tree
0297-serialize-and-deserialize-binary-tree
0450-delete-node-in-a-bst
0543-diameter-of-binary-tree
0653-two-sum-iv-input-is-a-bst
0662-maximum-width-of-binary-tree
0783-search-in-a-binary-search-tree
0784-insert-into-a-binary-search-tree
0893-all-nodes-distance-k-in-binary-tree
1029-vertical-order-traversal-of-a-binary-tree
1050-construct-binary-search-tree-from-preorder-traversal

Binary Search Tree

0098-validate-binary-search-tree
0099-recover-binary-search-tree
0173-binary-search-tree-iterator
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

Iterator

0173-binary-search-tree-iterator

Trie

0139-word-break
0208-implement-trie-prefix-tree
0421-maximum-xor-of-two-numbers-in-an-array
1826-maximum-xor-with-an-element-from-array

Union Find

0130-surrounded-regions
0547-number-of-provinces
0801-is-graph-bipartite
1073-number-of-enclaves

Graph

0207-course-schedule
0210-course-schedule-ii
0547-number-of-provinces
0801-is-graph-bipartite
0820-find-eventual-safe-states

Topological Sort

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

Memoization

0070-climbing-stairs
0139-word-break