LeetCode Topics

Array

0001-two-sum
0015-3sum
0016-3sum-closest
0018-4sum
0027-remove-element
0033-search-in-rotated-sorted-array
0034-find-first-and-last-position-of-element-in-sorted-array
0048-rotate-image
0049-group-anagrams
0053-maximum-subarray
0054-spiral-matrix
0066-plus-one
0073-set-matrix-zeroes
0075-sort-colors
0078-subsets
0088-merge-sorted-array
0118-pascals-triangle
0119-pascals-triangle-ii
0121-best-time-to-buy-and-sell-stock
0122-best-time-to-buy-and-sell-stock-ii
0128-longest-consecutive-sequence
0136-single-number
0137-single-number-ii
0152-maximum-product-subarray
0167-two-sum-ii-input-array-is-sorted
0169-majority-element
0179-largest-number
0189-rotate-array
0198-house-robber
0200-number-of-islands
0204-count-primes
0213-house-robber-ii
0215-kth-largest-element-in-an-array
0217-contains-duplicate
0219-contains-duplicate-ii
0228-summary-ranges
0229-majority-element-ii
0238-product-of-array-except-self
0260-single-number-iii
0268-missing-number
0283-move-zeroes
0300-longest-increasing-subsequence
0303-range-sum-query-immutable
0304-range-sum-query-2d-immutable
0309-best-time-to-buy-and-sell-stock-with-cooldown
0322-coin-change
0347-top-k-frequent-elements
0349-intersection-of-two-arrays
0414-third-maximum-number
0416-partition-equal-subset-sum
0448-find-all-numbers-disappeared-in-an-array
0453-minimum-moves-to-equal-array-elements
0455-assign-cookies
0485-max-consecutive-ones
0494-target-sum
0496-next-greater-element-i
0503-next-greater-element-ii
0518-coin-change-ii
0575-distribute-candies
0605-can-place-flowers
0682-baseball-game
0695-max-area-of-island
0697-degree-of-an-array
0739-daily-temperatures
0747-min-cost-climbing-stairs
0780-max-chunks-to-make-sorted
0817-design-hashmap
0837-most-common-word
0898-transpose-matrix
0941-sort-array-by-parity
0958-sort-array-by-parity-ii
0965-unique-email-addresses
1044-find-common-characters
1046-max-consecutive-ones-iii
1137-height-checker
1168-duplicate-zeros
1231-replace-elements-with-greatest-element-on-right-side
1256-rank-transform-of-an-array
1293-three-consecutive-odds
1306-minimum-absolute-difference
1319-unique-number-of-occurrences
1349-check-if-it-is-a-straight-line
1464-reduce-array-size-to-the-half
1476-count-negative-numbers-in-a-sorted-matrix
1528-kids-with-the-greatest-number-of-candies
1580-shuffle-the-array
1603-running-sum-of-1d-array
1635-number-of-good-pairs
1677-matrix-diagonal-sum
1720-crawler-log-folder
1741-sort-array-by-increasing-frequency
1791-richest-customer-wealth
1839-decode-xored-array
1993-sum-of-all-subset-xor-totals
2502-sort-the-people

Hash Table

0001-two-sum
0003-longest-substring-without-repeating-characters
0012-integer-to-roman
0013-roman-to-integer
0049-group-anagrams
0073-set-matrix-zeroes
0128-longest-consecutive-sequence
0141-linked-list-cycle
0160-intersection-of-two-linked-lists
0169-majority-element
0202-happy-number
0205-isomorphic-strings
0217-contains-duplicate
0219-contains-duplicate-ii
0229-majority-element-ii
0242-valid-anagram
0268-missing-number
0347-top-k-frequent-elements
0349-intersection-of-two-arrays
0387-first-unique-character-in-a-string
0389-find-the-difference
0409-longest-palindrome
0438-find-all-anagrams-in-a-string
0448-find-all-numbers-disappeared-in-an-array
0496-next-greater-element-i
0575-distribute-candies
0697-degree-of-an-array
0782-jewels-and-stones
0817-design-hashmap
0837-most-common-word
0965-unique-email-addresses
1044-find-common-characters
1256-rank-transform-of-an-array
1319-unique-number-of-occurrences
1464-reduce-array-size-to-the-half
1635-number-of-good-pairs
1741-sort-array-by-increasing-frequency
1770-minimum-deletions-to-make-character-frequencies-unique
2502-sort-the-people

Divide and Conquer

0053-maximum-subarray
0169-majority-element
0190-reverse-bits
0191-number-of-1-bits
0215-kth-largest-element-in-an-array
0347-top-k-frequent-elements

Sorting

0015-3sum
0016-3sum-closest
0018-4sum
0049-group-anagrams
0075-sort-colors
0088-merge-sorted-array
0169-majority-element
0179-largest-number
0215-kth-largest-element-in-an-array
0217-contains-duplicate
0229-majority-element-ii
0242-valid-anagram
0268-missing-number
0347-top-k-frequent-elements
0349-intersection-of-two-arrays
0389-find-the-difference
0414-third-maximum-number
0455-assign-cookies
0780-max-chunks-to-make-sorted
0941-sort-array-by-parity
0958-sort-array-by-parity-ii
1137-height-checker
1256-rank-transform-of-an-array
1306-minimum-absolute-difference
1464-reduce-array-size-to-the-half
1741-sort-array-by-increasing-frequency
1770-minimum-deletions-to-make-character-frequencies-unique
2502-sort-the-people

Counting

0169-majority-element
0229-majority-element-ii
0347-top-k-frequent-elements
0387-first-unique-character-in-a-string
0837-most-common-word
1635-number-of-good-pairs

Dynamic Programming

0005-longest-palindromic-substring
0053-maximum-subarray
0062-unique-paths
0070-climbing-stairs
0072-edit-distance
0091-decode-ways
0115-distinct-subsequences
0118-pascals-triangle
0119-pascals-triangle-ii
0121-best-time-to-buy-and-sell-stock
0122-best-time-to-buy-and-sell-stock-ii
0124-binary-tree-maximum-path-sum
0152-maximum-product-subarray
0198-house-robber
0213-house-robber-ii
0300-longest-increasing-subsequence
0309-best-time-to-buy-and-sell-stock-with-cooldown
0322-coin-change
0338-counting-bits
0392-is-subsequence
0416-partition-equal-subset-sum
0494-target-sum
0518-coin-change-ii
0647-palindromic-substrings
0747-min-cost-climbing-stairs
1250-longest-common-subsequence

Greedy

0122-best-time-to-buy-and-sell-stock-ii
0179-largest-number
0409-longest-palindrome
0455-assign-cookies
0605-can-place-flowers
0780-max-chunks-to-make-sorted
0957-minimum-add-to-make-parentheses-valid
1464-reduce-array-size-to-the-half
1770-minimum-deletions-to-make-character-frequencies-unique
2149-remove-colored-pieces-if-both-neighbors-are-the-same-color

Matrix

0048-rotate-image
0054-spiral-matrix
0073-set-matrix-zeroes
0200-number-of-islands
0304-range-sum-query-2d-immutable
0695-max-area-of-island
0898-transpose-matrix
1476-count-negative-numbers-in-a-sorted-matrix
1677-matrix-diagonal-sum
1791-richest-customer-wealth

Math

0007-reverse-integer
0009-palindrome-number
0012-integer-to-roman
0013-roman-to-integer
0043-multiply-strings
0048-rotate-image
0050-powx-n
0062-unique-paths
0066-plus-one
0067-add-binary
0070-climbing-stairs
0189-rotate-array
0202-happy-number
0204-count-primes
0231-power-of-two
0258-add-digits
0268-missing-number
0371-sum-of-two-integers
0453-minimum-moves-to-equal-array-elements
1349-check-if-it-is-a-straight-line
1635-number-of-good-pairs
1993-sum-of-all-subset-xor-totals
2149-remove-colored-pieces-if-both-neighbors-are-the-same-color
2491-smallest-even-multiple
2507-number-of-common-factors

String

0003-longest-substring-without-repeating-characters
0005-longest-palindromic-substring
0012-integer-to-roman
0013-roman-to-integer
0014-longest-common-prefix
0020-valid-parentheses
0028-find-the-index-of-the-first-occurrence-in-a-string
0043-multiply-strings
0049-group-anagrams
0058-length-of-last-word
0067-add-binary
0072-edit-distance
0091-decode-ways
0115-distinct-subsequences
0151-reverse-words-in-a-string
0179-largest-number
0205-isomorphic-strings
0242-valid-anagram
0345-reverse-vowels-of-a-string
0387-first-unique-character-in-a-string
0389-find-the-difference
0392-is-subsequence
0409-longest-palindrome
0438-find-all-anagrams-in-a-string
0557-reverse-words-in-a-string-iii
0647-palindromic-substrings
0782-jewels-and-stones
0837-most-common-word
0874-backspace-string-compare
0957-minimum-add-to-make-parentheses-valid
0965-unique-email-addresses
1044-find-common-characters
1250-longest-common-subsequence
1720-crawler-log-folder
1770-minimum-deletions-to-make-character-frequencies-unique
2076-sum-of-digits-of-string-after-convert
2149-remove-colored-pieces-if-both-neighbors-are-the-same-color
2502-sort-the-people

Two Pointers

0005-longest-palindromic-substring
0015-3sum
0016-3sum-closest
0018-4sum
0019-remove-nth-node-from-end-of-list
0027-remove-element
0028-find-the-index-of-the-first-occurrence-in-a-string
0061-rotate-list
0075-sort-colors
0088-merge-sorted-array
0141-linked-list-cycle
0143-reorder-list
0151-reverse-words-in-a-string
0160-intersection-of-two-linked-lists
0167-two-sum-ii-input-array-is-sorted
0189-rotate-array
0202-happy-number
0234-palindrome-linked-list
0283-move-zeroes
0345-reverse-vowels-of-a-string
0349-intersection-of-two-arrays
0392-is-subsequence
0455-assign-cookies
0557-reverse-words-in-a-string-iii
0647-palindromic-substrings
0874-backspace-string-compare
0908-middle-of-the-linked-list
0941-sort-array-by-parity
0958-sort-array-by-parity-ii
1168-duplicate-zeros

Simulation

0043-multiply-strings
0054-spiral-matrix
0067-add-binary
0258-add-digits
0682-baseball-game
0874-backspace-string-compare
0898-transpose-matrix
2076-sum-of-digits-of-string-after-convert

Prefix Sum

0238-product-of-array-except-self
0303-range-sum-query-immutable
0304-range-sum-query-2d-immutable
1046-max-consecutive-ones-iii
1603-running-sum-of-1d-array

Bit Manipulation

0067-add-binary
0078-subsets
0136-single-number
0137-single-number-ii
0190-reverse-bits
0191-number-of-1-bits
0231-power-of-two
0260-single-number-iii
0268-missing-number
0338-counting-bits
0371-sum-of-two-integers
0389-find-the-difference
1839-decode-xored-array
1993-sum-of-all-subset-xor-totals

Recursion

0021-merge-two-sorted-lists
0050-powx-n
0143-reorder-list
0203-remove-linked-list-elements
0206-reverse-linked-list
0231-power-of-two
0234-palindrome-linked-list

Number Theory

0204-count-primes
0258-add-digits
2491-smallest-even-multiple
2507-number-of-common-factors

Binary Search

0033-search-in-rotated-sorted-array
0034-find-first-and-last-position-of-element-in-sorted-array
0167-two-sum-ii-input-array-is-sorted
0268-missing-number
0300-longest-increasing-subsequence
0349-intersection-of-two-arrays
1046-max-consecutive-ones-iii
1476-count-negative-numbers-in-a-sorted-matrix

Linked List

0019-remove-nth-node-from-end-of-list
0021-merge-two-sorted-lists
0061-rotate-list
0092-reverse-linked-list-ii
0141-linked-list-cycle
0143-reorder-list
0160-intersection-of-two-linked-lists
0203-remove-linked-list-elements
0206-reverse-linked-list
0234-palindrome-linked-list
0817-design-hashmap
0908-middle-of-the-linked-list

Design

0303-range-sum-query-immutable
0304-range-sum-query-2d-immutable
0817-design-hashmap

Hash Function

0572-subtree-of-another-tree
0817-design-hashmap

Sliding Window

0003-longest-substring-without-repeating-characters
0219-contains-duplicate-ii
0438-find-all-anagrams-in-a-string
1046-max-consecutive-ones-iii

Stack

0020-valid-parentheses
0094-binary-tree-inorder-traversal
0143-reorder-list
0144-binary-tree-preorder-traversal
0145-binary-tree-postorder-traversal
0234-palindrome-linked-list
0496-next-greater-element-i
0503-next-greater-element-ii
0682-baseball-game
0739-daily-temperatures
0780-max-chunks-to-make-sorted
0874-backspace-string-compare
0957-minimum-add-to-make-parentheses-valid
1720-crawler-log-folder

Monotonic Stack

0496-next-greater-element-i
0503-next-greater-element-ii
0739-daily-temperatures
0780-max-chunks-to-make-sorted

Heap (Priority Queue)

0215-kth-largest-element-in-an-array
0347-top-k-frequent-elements
1464-reduce-array-size-to-the-half

Quickselect

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

Backtracking

0078-subsets
0494-target-sum
1993-sum-of-all-subset-xor-totals

Combinatorics

0062-unique-paths
1993-sum-of-all-subset-xor-totals

Enumeration

0204-count-primes
1993-sum-of-all-subset-xor-totals
2507-number-of-common-factors

Counting Sort

1137-height-checker

Geometry

1349-check-if-it-is-a-straight-line

Queue

0387-first-unique-character-in-a-string

Game Theory

2149-remove-colored-pieces-if-both-neighbors-are-the-same-color

Trie

0014-longest-common-prefix

Union Find

0128-longest-consecutive-sequence
0200-number-of-islands
0695-max-area-of-island

Bucket Sort

0347-top-k-frequent-elements

Tree

0094-binary-tree-inorder-traversal
0098-validate-binary-search-tree
0100-same-tree
0101-symmetric-tree
0102-binary-tree-level-order-traversal
0104-maximum-depth-of-binary-tree
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
0530-minimum-absolute-difference-in-bst
0543-diameter-of-binary-tree
0572-subtree-of-another-tree
1544-count-good-nodes-in-binary-tree

Depth-First Search

0094-binary-tree-inorder-traversal
0098-validate-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
0144-binary-tree-preorder-traversal
0145-binary-tree-postorder-traversal
0199-binary-tree-right-side-view
0200-number-of-islands
0226-invert-binary-tree
0230-kth-smallest-element-in-a-bst
0235-lowest-common-ancestor-of-a-binary-search-tree
0530-minimum-absolute-difference-in-bst
0543-diameter-of-binary-tree
0572-subtree-of-another-tree
0695-max-area-of-island
1544-count-good-nodes-in-binary-tree

Breadth-First Search

0100-same-tree
0101-symmetric-tree
0102-binary-tree-level-order-traversal
0104-maximum-depth-of-binary-tree
0112-path-sum
0199-binary-tree-right-side-view
0200-number-of-islands
0226-invert-binary-tree
0322-coin-change
0530-minimum-absolute-difference-in-bst
0695-max-area-of-island
1544-count-good-nodes-in-binary-tree

Binary Tree

0094-binary-tree-inorder-traversal
0098-validate-binary-search-tree
0100-same-tree
0101-symmetric-tree
0102-binary-tree-level-order-traversal
0104-maximum-depth-of-binary-tree
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
0530-minimum-absolute-difference-in-bst
0543-diameter-of-binary-tree
0572-subtree-of-another-tree
1544-count-good-nodes-in-binary-tree

String Matching

0028-find-the-index-of-the-first-occurrence-in-a-string
0572-subtree-of-another-tree

Binary Search Tree

0098-validate-binary-search-tree
0230-kth-smallest-element-in-a-bst
0235-lowest-common-ancestor-of-a-binary-search-tree
0530-minimum-absolute-difference-in-bst

Memoization

0070-climbing-stairs