LeetCode Topics

Tree

0100-same-tree
0101-symmetric-tree
0103-binary-tree-zigzag-level-order-traversal
0114-flatten-binary-tree-to-linked-list
0124-binary-tree-maximum-path-sum
0199-binary-tree-right-side-view
0222-count-complete-tree-nodes
0226-invert-binary-tree
0235-lowest-common-ancestor-of-a-binary-search-tree
0297-serialize-and-deserialize-binary-tree
0543-diameter-of-binary-tree
0789-kth-largest-element-in-a-stream
0863-sum-of-distances-in-tree
0893-all-nodes-distance-k-in-binary-tree
0988-flip-equivalent-binary-trees
1029-vertical-order-traversal-of-a-binary-tree
1207-delete-nodes-and-return-forest
1653-number-of-good-leaf-nodes-pairs
2493-reverse-odd-levels-of-binary-tree
2545-height-of-binary-tree-after-subtree-removal-queries

Depth-First Search

0100-same-tree
0101-symmetric-tree
0114-flatten-binary-tree-to-linked-list
0124-binary-tree-maximum-path-sum
0133-clone-graph
0199-binary-tree-right-side-view
0200-number-of-islands
0207-course-schedule
0210-course-schedule-ii
0226-invert-binary-tree
0235-lowest-common-ancestor-of-a-binary-search-tree
0297-serialize-and-deserialize-binary-tree
0310-minimum-height-trees
0329-longest-increasing-path-in-a-matrix
0332-reconstruct-itinerary
0543-diameter-of-binary-tree
0547-number-of-provinces
0684-redundant-connection
0801-is-graph-bipartite
0820-find-eventual-safe-states
0863-sum-of-distances-in-tree
0871-keys-and-rooms
0893-all-nodes-distance-k-in-binary-tree
0988-flip-equivalent-binary-trees
1029-vertical-order-traversal-of-a-binary-tree
1073-number-of-enclaves
1207-delete-nodes-and-return-forest
1300-critical-connections-in-a-network
1380-number-of-closed-islands
1431-all-ancestors-of-a-node-in-a-directed-acyclic-graph
1442-number-of-operations-to-make-network-connected
1576-reorder-routes-to-make-all-paths-lead-to-the-city-zero
1653-number-of-good-leaf-nodes-pairs
2246-maximum-employees-to-be-invited-to-a-meeting
2493-reverse-odd-levels-of-binary-tree
2545-height-of-binary-tree-after-subtree-removal-queries
3720-minimize-the-maximum-edge-weight-of-graph

Binary Tree

0100-same-tree
0101-symmetric-tree
0103-binary-tree-zigzag-level-order-traversal
0114-flatten-binary-tree-to-linked-list
0124-binary-tree-maximum-path-sum
0199-binary-tree-right-side-view
0222-count-complete-tree-nodes
0226-invert-binary-tree
0235-lowest-common-ancestor-of-a-binary-search-tree
0297-serialize-and-deserialize-binary-tree
0543-diameter-of-binary-tree
0789-kth-largest-element-in-a-stream
0893-all-nodes-distance-k-in-binary-tree
0988-flip-equivalent-binary-trees
1029-vertical-order-traversal-of-a-binary-tree
1207-delete-nodes-and-return-forest
1653-number-of-good-leaf-nodes-pairs
2493-reverse-odd-levels-of-binary-tree
2545-height-of-binary-tree-after-subtree-removal-queries

Hash Table

0001-two-sum
0003-longest-substring-without-repeating-characters
0013-roman-to-integer
0041-first-missing-positive
0049-group-anagrams
0133-clone-graph
0139-word-break
0299-bulls-and-cows
0347-top-k-frequent-elements
0355-design-twitter
0424-longest-repeating-character-replacement
0451-sort-characters-by-frequency
0525-contiguous-array
0560-subarray-sum-equals-k
0648-replace-words
0659-split-array-into-consecutive-subsequences
0768-partition-labels
0778-reorganize-string
0862-find-and-replace-in-string
0876-hand-of-straights
0893-all-nodes-distance-k-in-binary-tree
0940-fruit-into-baskets
0976-minimum-area-rectangle
1029-vertical-order-traversal-of-a-binary-tree
1039-find-the-town-judge
1129-longest-string-chain
1145-number-of-submatrices-that-sum-to-target
1207-delete-nodes-and-return-forest
1249-snapshot-array
1273-compare-strings-by-frequency-of-the-smallest-character
1422-divide-array-in-sets-of-k-consecutive-numbers
1482-how-many-numbers-are-smaller-than-the-current-number
1986-largest-color-value-in-a-directed-graph
2107-find-unique-binary-string
2448-count-number-of-bad-pairs
3267-find-longest-special-substring-that-occurs-thrice-i
3699-count-special-subsequences

Two Pointers

0005-longest-palindromic-substring
0011-container-with-most-water
0015-3sum
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
0167-two-sum-ii-input-array-is-sorted
0189-rotate-array
0295-find-median-from-data-stream
0455-assign-cookies
0581-shortest-unsorted-continuous-subarray
0768-partition-labels
0827-expressive-words
1129-longest-string-chain
1894-merge-strings-alternately
2216-delete-the-middle-node-of-a-linked-list
2414-move-pieces-to-obtain-a-string

String

0003-longest-substring-without-repeating-characters
0005-longest-palindromic-substring
0006-zigzag-conversion
0010-regular-expression-matching
0013-roman-to-integer
0014-longest-common-prefix
0022-generate-parentheses
0028-find-the-index-of-the-first-occurrence-in-a-string
0032-longest-valid-parentheses
0038-count-and-say
0049-group-anagrams
0072-edit-distance
0131-palindrome-partitioning
0139-word-break
0179-largest-number
0214-shortest-palindrome
0297-serialize-and-deserialize-binary-tree
0299-bulls-and-cows
0394-decode-string
0402-remove-k-digits
0424-longest-repeating-character-replacement
0451-sort-characters-by-frequency
0648-replace-words
0768-partition-labels
0778-reorganize-string
0827-expressive-words
0862-find-and-replace-in-string
0873-guess-the-word
1129-longest-string-chain
1273-compare-strings-by-frequency-of-the-smallest-character
1371-minimum-remove-to-make-valid-parentheses
1443-minimum-distance-to-type-a-word-using-two-fingers
1508-longest-happy-prefix
1894-merge-strings-alternately
2107-find-unique-binary-string
2414-move-pieces-to-obtain-a-string
2687-lexicographically-smallest-beautiful-string
3235-minimum-cost-to-convert-string-i
3267-find-longest-special-substring-that-occurs-thrice-i

Greedy

0011-container-with-most-water
0045-jump-game-ii
0055-jump-game
0122-best-time-to-buy-and-sell-stock-ii
0134-gas-station
0135-candy
0179-largest-number
0402-remove-k-digits
0410-split-array-largest-sum
0455-assign-cookies
0581-shortest-unsorted-continuous-subarray
0659-split-array-into-consecutive-subsequences
0768-partition-labels
0778-reorganize-string
0876-hand-of-straights
1049-minimum-domino-rotations-for-equal-row
1422-divide-array-in-sets-of-k-consecutive-numbers
1633-minimum-number-of-increments-on-subarrays-to-form-a-target-array
2687-lexicographically-smallest-beautiful-string
3620-maximum-number-of-distinct-elements-after-operations
3647-zero-array-transformation-iii
3743-reschedule-meetings-for-maximum-free-time-i

Array

0001-two-sum
0011-container-with-most-water
0015-3sum
0031-next-permutation
0033-search-in-rotated-sorted-array
0040-combination-sum-ii
0041-first-missing-positive
0042-trapping-rain-water
0045-jump-game-ii
0049-group-anagrams
0053-maximum-subarray
0055-jump-game
0063-unique-paths-ii
0064-minimum-path-sum
0075-sort-colors
0085-maximal-rectangle
0088-merge-sorted-array
0118-pascals-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
0134-gas-station
0135-candy
0136-single-number
0139-word-break
0150-evaluate-reverse-polish-notation
0152-maximum-product-subarray
0162-find-peak-element
0167-two-sum-ii-input-array-is-sorted
0179-largest-number
0188-best-time-to-buy-and-sell-stock-iv
0189-rotate-array
0198-house-robber
0200-number-of-islands
0213-house-robber-ii
0221-maximal-square
0289-game-of-life
0300-longest-increasing-subsequence
0309-best-time-to-buy-and-sell-stock-with-cooldown
0315-count-of-smaller-numbers-after-self
0322-coin-change
0329-longest-increasing-path-in-a-matrix
0347-top-k-frequent-elements
0354-russian-doll-envelopes
0410-split-array-largest-sum
0416-partition-equal-subset-sum
0455-assign-cookies
0485-max-consecutive-ones
0525-contiguous-array
0560-subarray-sum-equals-k
0581-shortest-unsorted-continuous-subarray
0648-replace-words
0659-split-array-into-consecutive-subsequences
0735-asteroid-collision
0819-minimum-swaps-to-make-sequences-increasing
0827-expressive-words
0862-find-and-replace-in-string
0864-image-overlap
0873-guess-the-word
0876-hand-of-straights
0882-peak-index-in-a-mountain-array
0907-koko-eating-bananas
0912-random-pick-with-weight
0940-fruit-into-baskets
0943-sum-of-subarray-minimums
0967-minimum-falling-path-sum
0976-minimum-area-rectangle
0983-validate-stack-sequences
1039-find-the-town-judge
1046-max-consecutive-ones-iii
1049-minimum-domino-rotations-for-equal-row
1063-best-sightseeing-pair
1073-number-of-enclaves
1129-longest-string-chain
1145-number-of-submatrices-that-sum-to-target
1207-delete-nodes-and-return-forest
1249-snapshot-array
1273-compare-strings-by-frequency-of-the-smallest-character
1380-number-of-closed-islands
1414-shortest-path-in-a-grid-with-obstacles-elimination
1422-divide-array-in-sets-of-k-consecutive-numbers
1482-how-many-numbers-are-smaller-than-the-current-number
1485-minimum-cost-to-make-at-least-one-valid-path-in-a-grid
1538-maximum-points-you-can-obtain-from-cards
1549-longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit
1633-minimum-number-of-increments-on-subarrays-to-form-a-target-array
1669-minimum-cost-to-cut-a-stick
2107-find-unique-binary-string
2164-two-best-non-overlapping-events
2227-sum-of-subarray-ranges
2448-count-number-of-bad-pairs
2545-height-of-binary-tree-after-subtree-removal-queries
2711-minimum-time-to-visit-a-cell-in-a-grid
3235-minimum-cost-to-convert-string-i
3558-find-a-safe-walk-through-a-grid
3620-maximum-number-of-distinct-elements-after-operations
3643-zero-array-transformation-ii
3647-zero-array-transformation-iii
3699-count-special-subsequences
3743-reschedule-meetings-for-maximum-free-time-i
3763-separate-squares-i

Dynamic Programming

0005-longest-palindromic-substring
0010-regular-expression-matching
0022-generate-parentheses
0032-longest-valid-parentheses
0042-trapping-rain-water
0045-jump-game-ii
0053-maximum-subarray
0055-jump-game
0062-unique-paths
0063-unique-paths-ii
0064-minimum-path-sum
0070-climbing-stairs
0072-edit-distance
0085-maximal-rectangle
0118-pascals-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
0139-word-break
0152-maximum-product-subarray
0188-best-time-to-buy-and-sell-stock-iv
0198-house-robber
0213-house-robber-ii
0221-maximal-square
0300-longest-increasing-subsequence
0309-best-time-to-buy-and-sell-stock-with-cooldown
0322-coin-change
0329-longest-increasing-path-in-a-matrix
0354-russian-doll-envelopes
0410-split-array-largest-sum
0416-partition-equal-subset-sum
0552-student-attendance-record-ii
0819-minimum-swaps-to-make-sequences-increasing
0863-sum-of-distances-in-tree
0943-sum-of-subarray-minimums
0967-minimum-falling-path-sum
1063-best-sightseeing-pair
1129-longest-string-chain
1443-minimum-distance-to-type-a-word-using-two-fingers
1633-minimum-number-of-increments-on-subarrays-to-form-a-target-array
1669-minimum-cost-to-cut-a-stick
1986-largest-color-value-in-a-directed-graph
2164-two-best-non-overlapping-events

Matrix

0063-unique-paths-ii
0064-minimum-path-sum
0085-maximal-rectangle
0200-number-of-islands
0221-maximal-square
0289-game-of-life
0329-longest-increasing-path-in-a-matrix
0864-image-overlap
0967-minimum-falling-path-sum
1073-number-of-enclaves
1145-number-of-submatrices-that-sum-to-target
1380-number-of-closed-islands
1414-shortest-path-in-a-grid-with-obstacles-elimination
1485-minimum-cost-to-make-at-least-one-valid-path-in-a-grid
2711-minimum-time-to-visit-a-cell-in-a-grid
3558-find-a-safe-walk-through-a-grid

Breadth-First Search

0100-same-tree
0101-symmetric-tree
0103-binary-tree-zigzag-level-order-traversal
0133-clone-graph
0199-binary-tree-right-side-view
0200-number-of-islands
0207-course-schedule
0210-course-schedule-ii
0226-invert-binary-tree
0297-serialize-and-deserialize-binary-tree
0310-minimum-height-trees
0322-coin-change
0329-longest-increasing-path-in-a-matrix
0547-number-of-provinces
0684-redundant-connection
0801-is-graph-bipartite
0820-find-eventual-safe-states
0871-keys-and-rooms
0893-all-nodes-distance-k-in-binary-tree
1029-vertical-order-traversal-of-a-binary-tree
1073-number-of-enclaves
1380-number-of-closed-islands
1414-shortest-path-in-a-grid-with-obstacles-elimination
1431-all-ancestors-of-a-node-in-a-directed-acyclic-graph
1442-number-of-operations-to-make-network-connected
1485-minimum-cost-to-make-at-least-one-valid-path-in-a-grid
1576-reorder-routes-to-make-all-paths-lead-to-the-city-zero
2493-reverse-odd-levels-of-binary-tree
2545-height-of-binary-tree-after-subtree-removal-queries
2711-minimum-time-to-visit-a-cell-in-a-grid
3558-find-a-safe-walk-through-a-grid
3720-minimize-the-maximum-edge-weight-of-graph

Graph

0133-clone-graph
0207-course-schedule
0210-course-schedule-ii
0310-minimum-height-trees
0329-longest-increasing-path-in-a-matrix
0332-reconstruct-itinerary
0547-number-of-provinces
0684-redundant-connection
0801-is-graph-bipartite
0820-find-eventual-safe-states
0863-sum-of-distances-in-tree
0871-keys-and-rooms
1039-find-the-town-judge
1300-critical-connections-in-a-network
1431-all-ancestors-of-a-node-in-a-directed-acyclic-graph
1442-number-of-operations-to-make-network-connected
1485-minimum-cost-to-make-at-least-one-valid-path-in-a-grid
1576-reorder-routes-to-make-all-paths-lead-to-the-city-zero
1916-find-center-of-star-graph
1986-largest-color-value-in-a-directed-graph
2246-maximum-employees-to-be-invited-to-a-meeting
2711-minimum-time-to-visit-a-cell-in-a-grid
3235-minimum-cost-to-convert-string-i
3558-find-a-safe-walk-through-a-grid
3720-minimize-the-maximum-edge-weight-of-graph

Topological Sort

0207-course-schedule
0210-course-schedule-ii
0310-minimum-height-trees
0329-longest-increasing-path-in-a-matrix
0820-find-eventual-safe-states
1431-all-ancestors-of-a-node-in-a-directed-acyclic-graph
1986-largest-color-value-in-a-directed-graph
2246-maximum-employees-to-be-invited-to-a-meeting

Union Find

0200-number-of-islands
0547-number-of-provinces
0684-redundant-connection
0801-is-graph-bipartite
1073-number-of-enclaves
1380-number-of-closed-islands
1442-number-of-operations-to-make-network-connected

Design

0295-find-median-from-data-stream
0297-serialize-and-deserialize-binary-tree
0355-design-twitter
0789-kth-largest-element-in-a-stream
1249-snapshot-array

Binary Search Tree

0033-search-in-rotated-sorted-array
0162-find-peak-element
0167-two-sum-ii-input-array-is-sorted
0222-count-complete-tree-nodes
0235-lowest-common-ancestor-of-a-binary-search-tree
0300-longest-increasing-subsequence
0315-count-of-smaller-numbers-after-self
0354-russian-doll-envelopes
0410-split-array-largest-sum
0789-kth-largest-element-in-a-stream
0882-peak-index-in-a-mountain-array
0907-koko-eating-bananas
0912-random-pick-with-weight
1046-max-consecutive-ones-iii
1249-snapshot-array
1273-compare-strings-by-frequency-of-the-smallest-character
2164-two-best-non-overlapping-events
3267-find-longest-special-substring-that-occurs-thrice-i
3643-zero-array-transformation-ii
3720-minimize-the-maximum-edge-weight-of-graph
3763-separate-squares-i

String Matching

0028-find-the-index-of-the-first-occurrence-in-a-string
0214-shortest-palindrome
1508-longest-happy-prefix

Rolling Hash

0214-shortest-palindrome
1508-longest-happy-prefix

Hash Function

0214-shortest-palindrome
1508-longest-happy-prefix

Sliding Window

0003-longest-substring-without-repeating-characters
0424-longest-repeating-character-replacement
0940-fruit-into-baskets
1046-max-consecutive-ones-iii
1538-maximum-points-you-can-obtain-from-cards
1549-longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit
3267-find-longest-special-substring-that-occurs-thrice-i
3743-reschedule-meetings-for-maximum-free-time-i

Prefix Sum

0410-split-array-largest-sum
0525-contiguous-array
0560-subarray-sum-equals-k
0912-random-pick-with-weight
1046-max-consecutive-ones-iii
1145-number-of-submatrices-that-sum-to-target
1538-maximum-points-you-can-obtain-from-cards
3643-zero-array-transformation-ii
3647-zero-array-transformation-iii

Stack

0032-longest-valid-parentheses
0042-trapping-rain-water
0085-maximal-rectangle
0114-flatten-binary-tree-to-linked-list
0150-evaluate-reverse-polish-notation
0394-decode-string
0402-remove-k-digits
0581-shortest-unsorted-continuous-subarray
0735-asteroid-collision
0943-sum-of-subarray-minimums
0983-validate-stack-sequences
1371-minimum-remove-to-make-valid-parentheses
1633-minimum-number-of-increments-on-subarrays-to-form-a-target-array
2227-sum-of-subarray-ranges

Simulation

0289-game-of-life
0735-asteroid-collision
0983-validate-stack-sequences

Sorting

0015-3sum
0049-group-anagrams
0075-sort-colors
0088-merge-sorted-array
0179-largest-number
0295-find-median-from-data-stream
0347-top-k-frequent-elements
0354-russian-doll-envelopes
0451-sort-characters-by-frequency
0455-assign-cookies
0581-shortest-unsorted-continuous-subarray
0778-reorganize-string
0862-find-and-replace-in-string
0876-hand-of-straights
0976-minimum-area-rectangle
1029-vertical-order-traversal-of-a-binary-tree
1129-longest-string-chain
1273-compare-strings-by-frequency-of-the-smallest-character
1422-divide-array-in-sets-of-k-consecutive-numbers
1482-how-many-numbers-are-smaller-than-the-current-number
1669-minimum-cost-to-cut-a-stick
2164-two-best-non-overlapping-events
3620-maximum-number-of-distinct-elements-after-operations
3647-zero-array-transformation-iii

Counting

0299-bulls-and-cows
0347-top-k-frequent-elements
0451-sort-characters-by-frequency
0778-reorganize-string
1482-how-many-numbers-are-smaller-than-the-current-number
1986-largest-color-value-in-a-directed-graph
2448-count-number-of-bad-pairs
3267-find-longest-special-substring-that-occurs-thrice-i

Math

0002-add-two-numbers
0007-reverse-integer
0009-palindrome-number
0013-roman-to-integer
0062-unique-paths
0070-climbing-stairs
0150-evaluate-reverse-polish-notation
0189-rotate-array
0873-guess-the-word
0912-random-pick-with-weight
0976-minimum-area-rectangle
2448-count-number-of-bad-pairs
3699-count-special-subsequences

Randomized

0912-random-pick-with-weight

Recursion

0002-add-two-numbers
0010-regular-expression-matching
0206-reverse-linked-list
0394-decode-string

Monotonic Stack

0042-trapping-rain-water
0085-maximal-rectangle
0402-remove-k-digits
0581-shortest-unsorted-continuous-subarray
0943-sum-of-subarray-minimums
1633-minimum-number-of-increments-on-subarrays-to-form-a-target-array
2227-sum-of-subarray-ranges

Trie

0014-longest-common-prefix
0139-word-break
0648-replace-words

Heap (Priority Queue)

0023-merge-k-sorted-lists
0295-find-median-from-data-stream
0347-top-k-frequent-elements
0355-design-twitter
0451-sort-characters-by-frequency
0659-split-array-into-consecutive-subsequences
0778-reorganize-string
0789-kth-largest-element-in-a-stream
1485-minimum-cost-to-make-at-least-one-valid-path-in-a-grid
1549-longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit
2164-two-best-non-overlapping-events
2711-minimum-time-to-visit-a-cell-in-a-grid
3558-find-a-safe-walk-through-a-grid
3647-zero-array-transformation-iii

Bucket Sort

0347-top-k-frequent-elements
0451-sort-characters-by-frequency

Interactive

0873-guess-the-word

Game Theory

0873-guess-the-word

Data Stream

0295-find-median-from-data-stream
0789-kth-largest-element-in-a-stream

Divide and Conquer

0023-merge-k-sorted-lists
0053-maximum-subarray
0315-count-of-smaller-numbers-after-self
0347-top-k-frequent-elements

Quickselect

0347-top-k-frequent-elements

Queue

1549-longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit

Ordered Set

0315-count-of-smaller-numbers-after-self
1549-longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit

Monotonic Queue

1549-longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit

Bit Manipulation

0136-single-number
0222-count-complete-tree-nodes

Binary Indexed Tree

0315-count-of-smaller-numbers-after-self

Segment Tree

0315-count-of-smaller-numbers-after-self

Merge Sort

0023-merge-k-sorted-lists
0315-count-of-smaller-numbers-after-self

Geometry

0976-minimum-area-rectangle

Backtracking

0022-generate-parentheses
0040-combination-sum-ii
0131-palindrome-partitioning
1361-tiling-a-rectangle-with-the-fewest-squares
2107-find-unique-binary-string

Shortest Path

1485-minimum-cost-to-make-at-least-one-valid-path-in-a-grid
2711-minimum-time-to-visit-a-cell-in-a-grid
3235-minimum-cost-to-convert-string-i
3558-find-a-safe-walk-through-a-grid
3720-minimize-the-maximum-edge-weight-of-graph

Eulerian Circuit

0332-reconstruct-itinerary

Memoization

0070-climbing-stairs
0139-word-break
0329-longest-increasing-path-in-a-matrix
1986-largest-color-value-in-a-directed-graph

Linked List

0002-add-two-numbers
0023-merge-k-sorted-lists
0114-flatten-binary-tree-to-linked-list
0206-reverse-linked-list
0355-design-twitter
2216-delete-the-middle-node-of-a-linked-list

Enumeration

3699-count-special-subsequences

Biconnected Component

1300-critical-connections-in-a-network

Combinatorics

0062-unique-paths