Leetcode

LeetCode Topics

Array

0001-two-sum
0011-container-with-most-water
0015-3sum
0026-remove-duplicates-from-sorted-array
0027-remove-element
0033-search-in-rotated-sorted-array
0034-find-first-and-last-position-of-element-in-sorted-array
0035-search-insert-position
0036-valid-sudoku
0039-combination-sum
0045-jump-game-ii
0046-permutations
0048-rotate-image
0053-maximum-subarray
0054-spiral-matrix
0055-jump-game
0056-merge-intervals
0057-insert-interval
0063-unique-paths-ii
0064-minimum-path-sum
0066-plus-one
0073-set-matrix-zeroes
0074-search-a-2d-matrix
0079-word-search
0080-remove-duplicates-from-sorted-array-ii
0088-merge-sorted-array
0105-construct-binary-tree-from-preorder-and-inorder-traversal
0106-construct-binary-tree-from-inorder-and-postorder-traversal
0108-convert-sorted-array-to-binary-search-tree
0120-triangle
0121-best-time-to-buy-and-sell-stock
0122-best-time-to-buy-and-sell-stock-ii
0128-longest-consecutive-sequence
0130-surrounded-regions
0134-gas-station
0136-single-number
0137-single-number-ii
0139-word-break
0150-evaluate-reverse-polish-notation
0153-find-minimum-in-rotated-sorted-array
0162-find-peak-element
0167-two-sum-ii-input-array-is-sorted
0169-majority-element
0189-rotate-array
0198-house-robber
0200-number-of-islands
0209-minimum-size-subarray-sum
0215-kth-largest-element-in-an-array
0219-contains-duplicate-ii
0221-maximal-square
0228-summary-ranges
0238-product-of-array-except-self
0274-h-index
0289-game-of-life
0300-longest-increasing-subsequence
0322-coin-change
0373-find-k-pairs-with-smallest-sums
0380-insert-delete-getrandom-o1
0399-evaluate-division
0452-minimum-number-of-arrows-to-burst-balloons
0525-contiguous-array
0718-maximum-length-of-repeated-subarray
0733-flood-fill
0772-construct-quad-tree
0829-subdomain-visit-count
0954-maximum-sum-circular-subarray
1112-find-words-that-can-be-formed-by-characters
1709-alert-using-same-key-card-three-or-more-times-in-a-one-hour-period
1757-minimum-jumps-to-reach-home
2254-check-if-every-row-and-column-contains-all-numbers

Two Pointers

0005-longest-palindromic-substring
0011-container-with-most-water
0015-3sum
0019-remove-nth-node-from-end-of-list
0026-remove-duplicates-from-sorted-array
0027-remove-element
0028-find-the-index-of-the-first-occurrence-in-a-string
0080-remove-duplicates-from-sorted-array-ii
0082-remove-duplicates-from-sorted-list-ii
0086-partition-list
0088-merge-sorted-array
0125-valid-palindrome
0141-linked-list-cycle
0148-sort-list
0151-reverse-words-in-a-string
0167-two-sum-ii-input-array-is-sorted
0189-rotate-array
0202-happy-number
0392-is-subsequence

Sorting

0015-3sum
0056-merge-intervals
0088-merge-sorted-array
0148-sort-list
0169-majority-element
0215-kth-largest-element-in-an-array
0242-valid-anagram
0274-h-index
0452-minimum-number-of-arrows-to-burst-balloons
1709-alert-using-same-key-card-three-or-more-times-in-a-one-hour-period

Hash Table

0001-two-sum
0003-longest-substring-without-repeating-characters
0012-integer-to-roman
0013-roman-to-integer
0017-letter-combinations-of-a-phone-number
0036-valid-sudoku
0073-set-matrix-zeroes
0105-construct-binary-tree-from-preorder-and-inorder-traversal
0106-construct-binary-tree-from-inorder-and-postorder-traversal
0128-longest-consecutive-sequence
0133-clone-graph
0138-copy-list-with-random-pointer
0139-word-break
0141-linked-list-cycle
0146-lru-cache
0169-majority-element
0202-happy-number
0205-isomorphic-strings
0208-implement-trie-prefix-tree
0219-contains-duplicate-ii
0242-valid-anagram
0290-word-pattern
0380-insert-delete-getrandom-o1
0383-ransom-note
0433-minimum-genetic-mutation
0525-contiguous-array
0829-subdomain-visit-count
1112-find-words-that-can-be-formed-by-characters
1709-alert-using-same-key-card-three-or-more-times-in-a-one-hour-period
2254-check-if-every-row-and-column-contains-all-numbers

Divide and Conquer

0053-maximum-subarray
0105-construct-binary-tree-from-preorder-and-inorder-traversal
0106-construct-binary-tree-from-inorder-and-postorder-traversal
0108-convert-sorted-array-to-binary-search-tree
0148-sort-list
0169-majority-element
0190-reverse-bits
0191-number-of-1-bits
0215-kth-largest-element-in-an-array
0772-construct-quad-tree
0954-maximum-sum-circular-subarray

Counting

0169-majority-element
0383-ransom-note
0829-subdomain-visit-count
1112-find-words-that-can-be-formed-by-characters

String

0003-longest-substring-without-repeating-characters
0005-longest-palindromic-substring
0006-zigzag-conversion
0012-integer-to-roman
0013-roman-to-integer
0014-longest-common-prefix
0017-letter-combinations-of-a-phone-number
0020-valid-parentheses
0022-generate-parentheses
0028-find-the-index-of-the-first-occurrence-in-a-string
0058-length-of-last-word
0067-add-binary
0071-simplify-path
0072-edit-distance
0079-word-search
0097-interleaving-string
0125-valid-palindrome
0139-word-break
0151-reverse-words-in-a-string
0205-isomorphic-strings
0208-implement-trie-prefix-tree
0211-design-add-and-search-words-data-structure
0242-valid-anagram
0290-word-pattern
0383-ransom-note
0392-is-subsequence
0399-evaluate-division
0433-minimum-genetic-mutation
0829-subdomain-visit-count
1112-find-words-that-can-be-formed-by-characters
1709-alert-using-same-key-card-three-or-more-times-in-a-one-hour-period

Dynamic Programming

0005-longest-palindromic-substring
0022-generate-parentheses
0045-jump-game-ii
0053-maximum-subarray
0055-jump-game
0063-unique-paths-ii
0064-minimum-path-sum
0070-climbing-stairs
0072-edit-distance
0097-interleaving-string
0120-triangle
0121-best-time-to-buy-and-sell-stock
0122-best-time-to-buy-and-sell-stock-ii
0124-binary-tree-maximum-path-sum
0139-word-break
0198-house-robber
0221-maximal-square
0300-longest-increasing-subsequence
0322-coin-change
0392-is-subsequence
0718-maximum-length-of-repeated-subarray
0954-maximum-sum-circular-subarray
1757-minimum-jumps-to-reach-home

Binary Search

0033-search-in-rotated-sorted-array
0034-find-first-and-last-position-of-element-in-sorted-array
0035-search-insert-position
0069-sqrtx
0074-search-a-2d-matrix
0153-find-minimum-in-rotated-sorted-array
0162-find-peak-element
0167-two-sum-ii-input-array-is-sorted
0209-minimum-size-subarray-sum
0222-count-complete-tree-nodes
0300-longest-increasing-subsequence
0718-maximum-length-of-repeated-subarray

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
0452-minimum-number-of-arrows-to-burst-balloons

Sliding Window

0003-longest-substring-without-repeating-characters
0209-minimum-size-subarray-sum
0219-contains-duplicate-ii
0718-maximum-length-of-repeated-subarray

Prefix Sum

0209-minimum-size-subarray-sum
0238-product-of-array-except-self
0525-contiguous-array

Queue

0954-maximum-sum-circular-subarray

Monotonic Queue

0954-maximum-sum-circular-subarray

Matrix

0036-valid-sudoku
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
0130-surrounded-regions
0200-number-of-islands
0221-maximal-square
0289-game-of-life
0733-flood-fill
0772-construct-quad-tree
2254-check-if-every-row-and-column-contains-all-numbers

Tree

0098-validate-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
0108-convert-sorted-array-to-binary-search-tree
0112-path-sum
0114-flatten-binary-tree-to-linked-list
0117-populating-next-right-pointers-in-each-node-ii
0124-binary-tree-maximum-path-sum
0129-sum-root-to-leaf-numbers
0173-binary-search-tree-iterator
0199-binary-tree-right-side-view
0222-count-complete-tree-nodes
0226-invert-binary-tree
0230-kth-smallest-element-in-a-bst
0236-lowest-common-ancestor-of-a-binary-tree
0530-minimum-absolute-difference-in-bst
0637-average-of-levels-in-binary-tree
0772-construct-quad-tree

Depth-First Search

0079-word-search
0098-validate-binary-search-tree
0100-same-tree
0101-symmetric-tree
0104-maximum-depth-of-binary-tree
0112-path-sum
0114-flatten-binary-tree-to-linked-list
0117-populating-next-right-pointers-in-each-node-ii
0124-binary-tree-maximum-path-sum
0129-sum-root-to-leaf-numbers
0130-surrounded-regions
0133-clone-graph
0199-binary-tree-right-side-view
0200-number-of-islands
0207-course-schedule
0210-course-schedule-ii
0211-design-add-and-search-words-data-structure
0226-invert-binary-tree
0230-kth-smallest-element-in-a-bst
0236-lowest-common-ancestor-of-a-binary-tree
0399-evaluate-division
0530-minimum-absolute-difference-in-bst
0637-average-of-levels-in-binary-tree
0733-flood-fill

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
0112-path-sum
0117-populating-next-right-pointers-in-each-node-ii
0130-surrounded-regions
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
0399-evaluate-division
0433-minimum-genetic-mutation
0530-minimum-absolute-difference-in-bst
0637-average-of-levels-in-binary-tree
0733-flood-fill
1757-minimum-jumps-to-reach-home

Binary Tree

0098-validate-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
0108-convert-sorted-array-to-binary-search-tree
0112-path-sum
0114-flatten-binary-tree-to-linked-list
0117-populating-next-right-pointers-in-each-node-ii
0124-binary-tree-maximum-path-sum
0129-sum-root-to-leaf-numbers
0173-binary-search-tree-iterator
0199-binary-tree-right-side-view
0222-count-complete-tree-nodes
0226-invert-binary-tree
0230-kth-smallest-element-in-a-bst
0236-lowest-common-ancestor-of-a-binary-tree
0530-minimum-absolute-difference-in-bst
0637-average-of-levels-in-binary-tree

Linked List

0002-add-two-numbers
0019-remove-nth-node-from-end-of-list
0021-merge-two-sorted-lists
0082-remove-duplicates-from-sorted-list-ii
0086-partition-list
0092-reverse-linked-list-ii
0114-flatten-binary-tree-to-linked-list
0117-populating-next-right-pointers-in-each-node-ii
0138-copy-list-with-random-pointer
0141-linked-list-cycle
0146-lru-cache
0148-sort-list

Stack

0020-valid-parentheses
0071-simplify-path
0114-flatten-binary-tree-to-linked-list
0150-evaluate-reverse-polish-notation
0155-min-stack
0173-binary-search-tree-iterator

Design

0146-lru-cache
0155-min-stack
0173-binary-search-tree-iterator
0208-implement-trie-prefix-tree
0211-design-add-and-search-words-data-structure
0380-insert-delete-getrandom-o1

Binary Search Tree

0098-validate-binary-search-tree
0108-convert-sorted-array-to-binary-search-tree
0173-binary-search-tree-iterator
0230-kth-smallest-element-in-a-bst
0530-minimum-absolute-difference-in-bst

Iterator

0173-binary-search-tree-iterator

Backtracking

0017-letter-combinations-of-a-phone-number
0022-generate-parentheses
0039-combination-sum
0046-permutations
0077-combinations
0079-word-search

Heap (Priority Queue)

0215-kth-largest-element-in-an-array
0373-find-k-pairs-with-smallest-sums

Quickselect

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

Merge Sort

0148-sort-list

Math

0002-add-two-numbers
0009-palindrome-number
0012-integer-to-roman
0013-roman-to-integer
0048-rotate-image
0050-powx-n
0066-plus-one
0067-add-binary
0069-sqrtx
0070-climbing-stairs
0150-evaluate-reverse-polish-notation
0172-factorial-trailing-zeroes
0189-rotate-array
0202-happy-number
0380-insert-delete-getrandom-o1

Memoization

0070-climbing-stairs
0139-word-break

Trie

0014-longest-common-prefix
0139-word-break
0208-implement-trie-prefix-tree
0211-design-add-and-search-words-data-structure

Recursion

0002-add-two-numbers
0021-merge-two-sorted-lists
0050-powx-n

Doubly-Linked List

0146-lru-cache

Union Find

0128-longest-consecutive-sequence
0130-surrounded-regions
0200-number-of-islands
0399-evaluate-division

Simulation

0054-spiral-matrix
0067-add-binary
0289-game-of-life

Rolling Hash

0718-maximum-length-of-repeated-subarray

Hash Function

0718-maximum-length-of-repeated-subarray

Counting Sort

0274-h-index

Randomized

0380-insert-delete-getrandom-o1

String Matching

0028-find-the-index-of-the-first-occurrence-in-a-string

Graph

0133-clone-graph
0207-course-schedule
0210-course-schedule-ii
0399-evaluate-division

Shortest Path

0399-evaluate-division

Topological Sort

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

Bit Manipulation

0067-add-binary
0136-single-number
0137-single-number-ii
0190-reverse-bits
0191-number-of-1-bits
0222-count-complete-tree-nodes

Database

0175-combine-two-tables
0181-employees-earning-more-than-their-managers
0182-duplicate-emails