LeetCode Topics

Depth-First Search

0098-validate-binary-search-tree
0104-maximum-depth-of-binary-tree
0110-balanced-binary-tree
0111-minimum-depth-of-binary-tree
0133-clone-graph
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
0332-reconstruct-itinerary
0543-diameter-of-binary-tree
0547-number-of-provinces
0617-merge-two-binary-trees
0684-redundant-connection
0687-longest-univalue-path
0695-max-area-of-island
0743-network-delay-time
0744-network-delay-time
0803-cheapest-flights-within-k-stops
1092-maximum-difference-between-node-and-ancestor
1254-deepest-leaves-sum
2121-find-if-path-exists-in-graph
2206-detonate-the-maximum-bombs
2445-reachable-nodes-with-restrictions

Breadth-First Search

0102-binary-tree-level-order-traversal
0104-maximum-depth-of-binary-tree
0111-minimum-depth-of-binary-tree
0133-clone-graph
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
0617-merge-two-binary-trees
0684-redundant-connection
0695-max-area-of-island
0743-network-delay-time
0744-network-delay-time
0803-cheapest-flights-within-k-stops
0994-rotting-oranges
1254-deepest-leaves-sum
2038-nearest-exit-from-entrance-in-maze
2121-find-if-path-exists-in-graph
2206-detonate-the-maximum-bombs
2445-reachable-nodes-with-restrictions

Graph

0744-network-delay-time
0803-cheapest-flights-within-k-stops
2121-find-if-path-exists-in-graph
2206-detonate-the-maximum-bombs
2445-reachable-nodes-with-restrictions

Heap (Priority Queue)

0023-merge-k-sorted-lists
0215-kth-largest-element-in-an-array
0239-sliding-window-maximum
0332-reconstruct-itinerary
0347-top-k-frequent-elements
0692-top-k-frequent-words
0743-network-delay-time
0744-network-delay-time
0767-reorganize-string
0789-kth-largest-element-in-a-stream
0803-cheapest-flights-within-k-stops
0973-k-closest-points-to-origin
1014-k-closest-points-to-origin
1046-last-stone-weight
1094-car-pooling
1464-reduce-array-size-to-the-half
1955-seat-reservation-manager
2094-remove-stones-to-minimize-the-total
2300-construct-string-with-repeat-limit
2413-smallest-number-in-infinite-set
2422-query-kth-smallest-trimmed-number
2479-meeting-rooms-iii

Shortest Path

0743-network-delay-time
0744-network-delay-time
0803-cheapest-flights-within-k-stops

Dynamic Programming

0005-longest-palindromic-substring
0042-trapping-rain-water
0063-unique-paths-ii
0070-climbing-stairs
0091-decode-ways
0122-best-time-to-buy-and-sell-stock-ii
0139-word-break
0198-house-robber
0300-longest-increasing-subsequence
0322-coin-change
0410-split-array-largest-sum
0435-non-overlapping-intervals
0542-01-matrix
0714-best-time-to-buy-and-sell-stock-with-transaction-fee
0746-min-cost-climbing-stairs
0747-min-cost-climbing-stairs
0803-cheapest-flights-within-k-stops
0967-minimum-falling-path-sum
1081-video-stitching
1493-longest-subarray-of-1s-after-deleting-one-element

Tree

0098-validate-binary-search-tree
0102-binary-tree-level-order-traversal
0104-maximum-depth-of-binary-tree
0108-convert-sorted-array-to-binary-search-tree
0110-balanced-binary-tree
0111-minimum-depth-of-binary-tree
0199-binary-tree-right-side-view
0226-invert-binary-tree
0230-kth-smallest-element-in-a-bst
0543-diameter-of-binary-tree
0617-merge-two-binary-trees
0687-longest-univalue-path
0784-insert-into-a-binary-search-tree
0789-kth-largest-element-in-a-stream
1092-maximum-difference-between-node-and-ancestor
1254-deepest-leaves-sum
2445-reachable-nodes-with-restrictions

Binary Tree

0098-validate-binary-search-tree
0102-binary-tree-level-order-traversal
0104-maximum-depth-of-binary-tree
0108-convert-sorted-array-to-binary-search-tree
0110-balanced-binary-tree
0111-minimum-depth-of-binary-tree
0199-binary-tree-right-side-view
0226-invert-binary-tree
0230-kth-smallest-element-in-a-bst
0543-diameter-of-binary-tree
0617-merge-two-binary-trees
0687-longest-univalue-path
0784-insert-into-a-binary-search-tree
0789-kth-largest-element-in-a-stream
1092-maximum-difference-between-node-and-ancestor
1254-deepest-leaves-sum

Two Pointers

0005-longest-palindromic-substring
0011-container-with-most-water
0015-3sum
0042-trapping-rain-water
0075-sort-colors
0125-valid-palindrome
0148-sort-list
0167-two-sum-ii-input-array-is-sorted
0234-palindrome-linked-list
0283-move-zeroes
0344-reverse-string
0349-intersection-of-two-arrays
0455-assign-cookies
0557-reverse-words-in-a-string-iii
0567-permutation-in-string
0908-middle-of-the-linked-list
0953-reverse-only-letters
2128-reverse-prefix-of-word
2497-maximum-matching-of-players-with-trainers
2572-append-characters-to-string-to-make-subsequence
2634-minimum-common-value

String

0003-longest-substring-without-repeating-characters
0005-longest-palindromic-substring
0017-letter-combinations-of-a-phone-number
0020-valid-parentheses
0049-group-anagrams
0071-simplify-path
0076-minimum-window-substring
0091-decode-ways
0125-valid-palindrome
0139-word-break
0179-largest-number
0208-implement-trie-prefix-tree
0242-valid-anagram
0332-reconstruct-itinerary
0344-reverse-string
0383-ransom-note
0402-remove-k-digits
0409-longest-palindrome
0424-longest-repeating-character-replacement
0438-find-all-anagrams-in-a-string
0557-reverse-words-in-a-string-iii
0567-permutation-in-string
0692-top-k-frequent-words
0767-reorganize-string
0771-jewels-and-stones
0819-most-common-word
0953-reverse-only-letters
1249-minimum-remove-to-make-valid-parentheses
1297-maximum-number-of-balloons
1321-get-equal-substrings-within-budget
1456-maximum-number-of-vowels-in-a-substring-of-given-length
1567-maximum-number-of-vowels-in-a-substring-of-given-length
1666-make-the-string-great
1782-smallest-string-with-a-given-numeric-value
1876-substrings-of-size-three-with-distinct-characters
1960-check-if-the-sentence-is-pangram
2128-reverse-prefix-of-word
2300-construct-string-with-repeat-limit
2422-query-kth-smallest-trimmed-number
2470-removing-stars-from-a-string
2475-largest-palindromic-number
2487-optimal-partition-of-string
2572-append-characters-to-string-to-make-subsequence

Array

0011-container-with-most-water
0015-3sum
0033-search-in-rotated-sorted-array
0039-combination-sum
0042-trapping-rain-water
0046-permutations
0049-group-anagrams
0056-merge-intervals
0063-unique-paths-ii
0075-sort-colors
0078-subsets
0108-convert-sorted-array-to-binary-search-tree
0122-best-time-to-buy-and-sell-stock-ii
0136-single-number
0139-word-break
0150-evaluate-reverse-polish-notation
0153-find-minimum-in-rotated-sorted-array
0167-two-sum-ii-input-array-is-sorted
0179-largest-number
0198-house-robber
0200-number-of-islands
0209-minimum-size-subarray-sum
0215-kth-largest-element-in-an-array
0219-contains-duplicate-ii
0239-sliding-window-maximum
0240-search-a-2d-matrix-ii
0268-missing-number
0283-move-zeroes
0300-longest-increasing-subsequence
0303-range-sum-query-immutable
0322-coin-change
0332-reconstruct-itinerary
0347-top-k-frequent-elements
0349-intersection-of-two-arrays
0380-insert-delete-getrandom-o1
0410-split-array-largest-sum
0435-non-overlapping-intervals
0455-assign-cookies
0496-next-greater-element-i
0542-01-matrix
0560-subarray-sum-equals-k
0643-maximum-average-subarray-i
0692-top-k-frequent-words
0695-max-area-of-island
0713-subarray-product-less-than-k
0714-best-time-to-buy-and-sell-stock-with-transaction-fee
0739-daily-temperatures
0746-min-cost-climbing-stairs
0747-min-cost-climbing-stairs
0819-most-common-word
0875-koko-eating-bananas
0904-fruit-into-baskets
0930-binary-subarrays-with-sum
0967-minimum-falling-path-sum
0973-k-closest-points-to-origin
0994-rotting-oranges
1004-max-consecutive-ones-iii
1011-capacity-to-ship-packages-within-d-days
1014-k-closest-points-to-origin
1046-last-stone-weight
1047-maximize-sum-of-array-after-k-negations
1081-video-stitching
1094-car-pooling
1248-count-number-of-nice-subarrays
1343-number-of-sub-arrays-of-size-k-and-average-greater-than-or-equal-to-threshold
1408-find-the-smallest-divisor-given-a-threshold
1464-reduce-array-size-to-the-half
1493-longest-subarray-of-1s-after-deleting-one-element
1658-minimum-operations-to-reduce-x-to-zero
1829-maximum-units-on-a-truck
1833-find-the-highest-altitude
1961-maximum-ice-cream-bars
2038-nearest-exit-from-entrance-in-maze
2090-k-radius-subarray-averages
2094-remove-stones-to-minimize-the-total
2206-detonate-the-maximum-bombs
2422-query-kth-smallest-trimmed-number
2445-reachable-nodes-with-restrictions
2469-longest-subsequence-with-limited-sum
2479-meeting-rooms-iii
2497-maximum-matching-of-players-with-trainers
2634-minimum-common-value
3225-length-of-longest-subarray-with-at-most-k-frequency

Hash Table

0003-longest-substring-without-repeating-characters
0017-letter-combinations-of-a-phone-number
0049-group-anagrams
0076-minimum-window-substring
0133-clone-graph
0139-word-break
0146-lru-cache
0208-implement-trie-prefix-tree
0219-contains-duplicate-ii
0242-valid-anagram
0268-missing-number
0347-top-k-frequent-elements
0349-intersection-of-two-arrays
0380-insert-delete-getrandom-o1
0383-ransom-note
0409-longest-palindrome
0424-longest-repeating-character-replacement
0438-find-all-anagrams-in-a-string
0496-next-greater-element-i
0560-subarray-sum-equals-k
0567-permutation-in-string
0692-top-k-frequent-words
0767-reorganize-string
0771-jewels-and-stones
0819-most-common-word
0904-fruit-into-baskets
0930-binary-subarrays-with-sum
1248-count-number-of-nice-subarrays
1297-maximum-number-of-balloons
1464-reduce-array-size-to-the-half
1658-minimum-operations-to-reduce-x-to-zero
1876-substrings-of-size-three-with-distinct-characters
1960-check-if-the-sentence-is-pangram
2300-construct-string-with-repeat-limit
2413-smallest-number-in-infinite-set
2445-reachable-nodes-with-restrictions
2475-largest-palindromic-number
2479-meeting-rooms-iii
2487-optimal-partition-of-string
2634-minimum-common-value
3225-length-of-longest-subarray-with-at-most-k-frequency

Binary Search

0033-search-in-rotated-sorted-array
0153-find-minimum-in-rotated-sorted-array
0167-two-sum-ii-input-array-is-sorted
0209-minimum-size-subarray-sum
0240-search-a-2d-matrix-ii
0268-missing-number
0300-longest-increasing-subsequence
0349-intersection-of-two-arrays
0410-split-array-largest-sum
0713-subarray-product-less-than-k
0875-koko-eating-bananas
1004-max-consecutive-ones-iii
1011-capacity-to-ship-packages-within-d-days
1321-get-equal-substrings-within-budget
1408-find-the-smallest-divisor-given-a-threshold
1658-minimum-operations-to-reduce-x-to-zero
2469-longest-subsequence-with-limited-sum
2634-minimum-common-value

Stack

0020-valid-parentheses
0042-trapping-rain-water
0071-simplify-path
0150-evaluate-reverse-polish-notation
0155-min-stack
0232-implement-queue-using-stacks
0234-palindrome-linked-list
0402-remove-k-digits
0496-next-greater-element-i
0739-daily-temperatures
0937-online-stock-span
1249-minimum-remove-to-make-valid-parentheses
1666-make-the-string-great
2128-reverse-prefix-of-word
2470-removing-stars-from-a-string

Sliding Window

0003-longest-substring-without-repeating-characters
0076-minimum-window-substring
0209-minimum-size-subarray-sum
0219-contains-duplicate-ii
0239-sliding-window-maximum
0424-longest-repeating-character-replacement
0438-find-all-anagrams-in-a-string
0567-permutation-in-string
0643-maximum-average-subarray-i
0713-subarray-product-less-than-k
0904-fruit-into-baskets
0930-binary-subarrays-with-sum
1004-max-consecutive-ones-iii
1248-count-number-of-nice-subarrays
1321-get-equal-substrings-within-budget
1343-number-of-sub-arrays-of-size-k-and-average-greater-than-or-equal-to-threshold
1456-maximum-number-of-vowels-in-a-substring-of-given-length
1493-longest-subarray-of-1s-after-deleting-one-element
1567-maximum-number-of-vowels-in-a-substring-of-given-length
1658-minimum-operations-to-reduce-x-to-zero
1876-substrings-of-size-three-with-distinct-characters
2090-k-radius-subarray-averages
3225-length-of-longest-subarray-with-at-most-k-frequency

Prefix Sum

0209-minimum-size-subarray-sum
0303-range-sum-query-immutable
0410-split-array-largest-sum
0560-subarray-sum-equals-k
0713-subarray-product-less-than-k
0930-binary-subarrays-with-sum
1004-max-consecutive-ones-iii
1094-car-pooling
1248-count-number-of-nice-subarrays
1321-get-equal-substrings-within-budget
1658-minimum-operations-to-reduce-x-to-zero
1833-find-the-highest-altitude
2469-longest-subsequence-with-limited-sum

Math

0002-add-two-numbers
0070-climbing-stairs
0150-evaluate-reverse-polish-notation
0268-missing-number
0380-insert-delete-getrandom-o1
0973-k-closest-points-to-origin
1014-k-closest-points-to-origin
1248-count-number-of-nice-subarrays
1303-minimum-moves-to-reach-target-score
1448-maximum-69-number
2206-detonate-the-maximum-bombs
2279-maximum-split-of-positive-even-integers
2544-minimum-addition-to-make-integer-beautiful

Bit Manipulation

0078-subsets
0136-single-number
0191-number-of-1-bits
0268-missing-number
0461-hamming-distance

Sorting

0015-3sum
0049-group-anagrams
0056-merge-intervals
0075-sort-colors
0148-sort-list
0179-largest-number
0215-kth-largest-element-in-an-array
0242-valid-anagram
0268-missing-number
0332-reconstruct-itinerary
0347-top-k-frequent-elements
0349-intersection-of-two-arrays
0435-non-overlapping-intervals
0455-assign-cookies
0692-top-k-frequent-words
0767-reorganize-string
0973-k-closest-points-to-origin
1014-k-closest-points-to-origin
1047-maximize-sum-of-array-after-k-negations
1094-car-pooling
1464-reduce-array-size-to-the-half
1829-maximum-units-on-a-truck
1961-maximum-ice-cream-bars
2422-query-kth-smallest-trimmed-number
2469-longest-subsequence-with-limited-sum
2479-meeting-rooms-iii
2497-maximum-matching-of-players-with-trainers

Design

0146-lru-cache
0155-min-stack
0208-implement-trie-prefix-tree
0232-implement-queue-using-stacks
0303-range-sum-query-immutable
0380-insert-delete-getrandom-o1
0789-kth-largest-element-in-a-stream
0937-online-stock-span
1955-seat-reservation-manager
2413-smallest-number-in-infinite-set

Counting

0347-top-k-frequent-elements
0383-ransom-note
0692-top-k-frequent-words
0767-reorganize-string
0819-most-common-word
1297-maximum-number-of-balloons
1876-substrings-of-size-three-with-distinct-characters
2300-construct-string-with-repeat-limit
2475-largest-palindromic-number

Divide and Conquer

0023-merge-k-sorted-lists
0108-convert-sorted-array-to-binary-search-tree
0148-sort-list
0191-number-of-1-bits
0215-kth-largest-element-in-an-array
0240-search-a-2d-matrix-ii
0347-top-k-frequent-elements
0973-k-closest-points-to-origin
1014-k-closest-points-to-origin
2422-query-kth-smallest-trimmed-number

Binary Search Tree

0098-validate-binary-search-tree
0108-convert-sorted-array-to-binary-search-tree
0230-kth-smallest-element-in-a-bst
0784-insert-into-a-binary-search-tree
0789-kth-largest-element-in-a-stream

Quickselect

0215-kth-largest-element-in-an-array
0347-top-k-frequent-elements
0973-k-closest-points-to-origin
1014-k-closest-points-to-origin
2422-query-kth-smallest-trimmed-number

Simulation

1094-car-pooling
2470-removing-stars-from-a-string
2479-meeting-rooms-iii

Union Find

0695-max-area-of-island
2121-find-if-path-exists-in-graph
2445-reachable-nodes-with-restrictions

Matrix

0063-unique-paths-ii
0200-number-of-islands
0240-search-a-2d-matrix-ii
0542-01-matrix
0695-max-area-of-island
0967-minimum-falling-path-sum
0994-rotting-oranges
2038-nearest-exit-from-entrance-in-maze

Geometry

0973-k-closest-points-to-origin
1014-k-closest-points-to-origin
2206-detonate-the-maximum-bombs

Linked List

0002-add-two-numbers
0021-merge-two-sorted-lists
0023-merge-k-sorted-lists
0083-remove-duplicates-from-sorted-list
0146-lru-cache
0148-sort-list
0206-reverse-linked-list
0234-palindrome-linked-list
0328-odd-even-linked-list
0908-middle-of-the-linked-list

Greedy

0011-container-with-most-water
0122-best-time-to-buy-and-sell-stock-ii
0179-largest-number
0402-remove-k-digits
0409-longest-palindrome
0410-split-array-largest-sum
0435-non-overlapping-intervals
0455-assign-cookies
0714-best-time-to-buy-and-sell-stock-with-transaction-fee
0767-reorganize-string
1047-maximize-sum-of-array-after-k-negations
1081-video-stitching
1303-minimum-moves-to-reach-target-score
1448-maximum-69-number
1464-reduce-array-size-to-the-half
1782-smallest-string-with-a-given-numeric-value
1829-maximum-units-on-a-truck
1961-maximum-ice-cream-bars
2094-remove-stones-to-minimize-the-total
2279-maximum-split-of-positive-even-integers
2300-construct-string-with-repeat-limit
2469-longest-subsequence-with-limited-sum
2475-largest-palindromic-number
2487-optimal-partition-of-string
2497-maximum-matching-of-players-with-trainers
2544-minimum-addition-to-make-integer-beautiful
2572-append-characters-to-string-to-make-subsequence

Queue

0232-implement-queue-using-stacks
0239-sliding-window-maximum

Monotonic Queue

0239-sliding-window-maximum

Monotonic Stack

0042-trapping-rain-water
0402-remove-k-digits
0496-next-greater-element-i
0739-daily-temperatures
0937-online-stock-span

Data Stream

0789-kth-largest-element-in-a-stream
0937-online-stock-span

Radix Sort

2422-query-kth-smallest-trimmed-number

Trie

0139-word-break
0208-implement-trie-prefix-tree
0692-top-k-frequent-words

Bucket Sort

0347-top-k-frequent-elements
0692-top-k-frequent-words

Ordered Set

2413-smallest-number-in-infinite-set

Counting Sort

1961-maximum-ice-cream-bars

Backtracking

0017-letter-combinations-of-a-phone-number
0039-combination-sum
0046-permutations
0052-n-queens-ii
0077-combinations
0078-subsets
2279-maximum-split-of-positive-even-integers

Memoization

0070-climbing-stairs
0139-word-break

Manacher

0005-longest-palindromic-substring

Recursion

0002-add-two-numbers
0021-merge-two-sorted-lists
0206-reverse-linked-list
0234-palindrome-linked-list

Bracket Sequences

0020-valid-parentheses

Merge Sort

0023-merge-k-sorted-lists
0148-sort-list

Tournament Sort

0023-merge-k-sorted-lists

K-D Tree

0973-k-closest-points-to-origin

Union-Find

0200-number-of-islands
0547-number-of-provinces
0684-redundant-connection

Graph Theory

0133-clone-graph
0207-course-schedule
0210-course-schedule-ii
0332-reconstruct-itinerary
0547-number-of-provinces
0684-redundant-connection
0743-network-delay-time

Eulerian Circuit

0332-reconstruct-itinerary

Eulerian Path

0332-reconstruct-itinerary

Semi-Eulerian Graph

0332-reconstruct-itinerary

Topological Sort

0207-course-schedule
0210-course-schedule-ii

Directed Acyclic Graph

0207-course-schedule

Dijkstra's Algorithm

0743-network-delay-time

Quicksort

0056-merge-intervals

DP on Trees

0543-diameter-of-binary-tree

Knapsack Problem

0322-coin-change

Complete Knapsack

0322-coin-change

Longest Increasing Subsequence

0300-longest-increasing-subsequence

Doubly-Linked List

0146-lru-cache

Randomized

0380-insert-delete-getrandom-o1

Brute-Force Search

0139-word-break