A collection of LeetCode questions to ace the coding interview! - Created using LeetHub v2

LeetCode Topics

Array

0001-two-sum
0011-container-with-most-water
0031-next-permutation
0033-search-in-rotated-sorted-array
0045-jump-game-ii
0049-group-anagrams
0053-maximum-subarray
0054-spiral-matrix
0055-jump-game
0056-merge-intervals
0057-insert-interval
0059-spiral-matrix-ii
0063-unique-paths-ii
0064-minimum-path-sum
0073-set-matrix-zeroes
0074-search-a-2d-matrix
0075-sort-colors
0079-word-search
0080-remove-duplicates-from-sorted-array-ii
0081-search-in-rotated-sorted-array-ii
0090-subsets-ii
0105-construct-binary-tree-from-preorder-and-inorder-traversal
0106-construct-binary-tree-from-inorder-and-postorder-traversal
0120-triangle
0121-best-time-to-buy-and-sell-stock
0122-best-time-to-buy-and-sell-stock-ii
0130-surrounded-regions
0134-gas-station
0135-candy
0139-word-break
0152-maximum-product-subarray
0153-find-minimum-in-rotated-sorted-array
0162-find-peak-element
0169-majority-element
0189-rotate-array
0198-house-robber
0204-count-primes
0209-minimum-size-subarray-sum
0213-house-robber-ii
0215-kth-largest-element-in-an-array
0216-combination-sum-iii
0217-contains-duplicate
0219-contains-duplicate-ii
0221-maximal-square
0229-majority-element-ii
0238-product-of-array-except-self
0240-search-a-2d-matrix-ii
0268-missing-number
0274-h-index
0275-h-index-ii
0283-move-zeroes
0300-longest-increasing-subsequence
0309-best-time-to-buy-and-sell-stock-with-cooldown
0334-increasing-triplet-subsequence
0349-intersection-of-two-arrays
0350-intersection-of-two-arrays-ii
0454-4sum-ii
0455-assign-cookies
0456-132-pattern
0463-island-perimeter
0495-teemo-attacking
0498-diagonal-traverse
0522-longest-uncommon-subsequence-ii
0523-continuous-subarray-sum
0561-array-partition
0566-reshape-the-matrix
0598-range-addition-ii
0599-minimum-index-sum-of-two-lists
0605-can-place-flowers
0643-maximum-average-subarray-i
0645-set-mismatch
0674-longest-continuous-increasing-subsequence
0697-degree-of-an-array
0714-best-time-to-buy-and-sell-stock-with-transaction-fee
0724-find-pivot-index
0735-asteroid-collision
0745-find-smallest-letter-greater-than-target
0747-min-cost-climbing-stairs
0748-largest-number-at-least-twice-of-others
0777-toeplitz-matrix
0792-binary-search
0822-unique-morse-code-words
0824-number-of-lines-to-write-string
0837-most-common-word
0841-shortest-distance-to-a-character
0859-design-circular-deque
0861-flipping-an-image
0898-transpose-matrix
0907-koko-eating-bananas
0917-boats-to-save-people
0924-fair-candy-swap
0925-construct-binary-tree-from-preorder-and-postorder-traversal
0941-sort-array-by-parity
0944-smallest-range-i
0965-unique-email-addresses
0978-valid-mountain-array
1001-n-repeated-element-in-size-2n-array
1018-largest-perimeter-triangle
1031-add-to-array-form-of-integer
1036-rotting-oranges
1039-find-the-town-judge
1044-find-common-characters
1046-max-consecutive-ones-iii
1047-maximize-sum-of-array-after-k-negations
1062-partition-array-into-three-parts-with-equal-sum
1115-valid-boomerang
1137-height-checker
1293-three-consecutive-odds
1364-tuple-with-same-product
1386-shift-2d-grid
1392-find-the-difference-of-two-arrays
1421-find-numbers-with-even-number-of-digits
1458-sort-integers-by-the-number-of-1-bits
1476-count-negative-numbers-in-a-sorted-matrix
1477-product-of-the-last-k-numbers
1482-how-many-numbers-are-smaller-than-the-current-number
1496-lucky-numbers-in-a-matrix
1505-create-target-array-in-the-given-order
1556-make-two-arrays-equal-by-reversing-subarrays
1626-can-make-arithmetic-progression-from-sequence
1635-number-of-good-pairs
1656-count-good-triplets
1682-most-visited-sector-in-a-circular-track
1689-detect-pattern-of-length-m-repeated-k-or-more-times
1694-make-sum-divisible-by-p
1798-max-number-of-k-sum-pairs
1833-find-the-highest-altitude
1843-number-of-rectangles-that-can-form-the-largest-square
2215-finding-3-digit-even-numbers
2220-find-all-possible-recipes-from-given-supplies
2232-adding-spaces-to-a-string
2237-longest-palindrome-by-concatenating-two-letter-words
2277-count-equal-and-divisible-pairs-in-an-array
2392-successful-pairs-of-spells-and-potions
2394-count-subarrays-with-score-less-than-k
2411-spiral-matrix-iv
2448-count-number-of-bad-pairs
2478-longest-nice-subarray
2503-longest-subarray-with-maximum-bitwise-and
2551-apply-operations-to-an-array
2581-divide-players-into-teams-of-equal-skill
2614-maximum-count-of-positive-integer-and-negative-integer
2626-count-the-number-of-good-subarrays
3154-maximum-value-of-an-ordered-triplet-i
3194-find-words-containing-character
3321-type-of-triangle
3348-minimum-cost-walk-in-weighted-graph
3430-count-days-without-meetings
3434-find-the-number-of-distinct-colors-among-the-balls
3483-alternating-groups-ii
3639-zero-array-transformation-i
3643-zero-array-transformation-ii
3647-zero-array-transformation-iii
3747-maximum-difference-between-adjacent-elements-in-a-circular-array

Linked List

0021-merge-two-sorted-lists
0024-swap-nodes-in-pairs
0082-remove-duplicates-from-sorted-list-ii
0086-partition-list
0092-reverse-linked-list-ii
0109-convert-sorted-list-to-binary-search-tree
0114-flatten-binary-tree-to-linked-list
0142-linked-list-cycle-ii
0148-sort-list
0203-remove-linked-list-elements
0206-reverse-linked-list
0328-odd-even-linked-list
0859-design-circular-deque
0908-middle-of-the-linked-list
2411-spiral-matrix-iv

Matrix

0054-spiral-matrix
0059-spiral-matrix-ii
0063-unique-paths-ii
0064-minimum-path-sum
0073-set-matrix-zeroes
0074-search-a-2d-matrix
0079-word-search
0130-surrounded-regions
0221-maximal-square
0240-search-a-2d-matrix-ii
0463-island-perimeter
0498-diagonal-traverse
0566-reshape-the-matrix
0777-toeplitz-matrix
0861-flipping-an-image
0898-transpose-matrix
1036-rotting-oranges
1386-shift-2d-grid
1476-count-negative-numbers-in-a-sorted-matrix
1496-lucky-numbers-in-a-matrix
2411-spiral-matrix-iv

Simulation

0054-spiral-matrix
0059-spiral-matrix-ii
0258-add-digits
0495-teemo-attacking
0498-diagonal-traverse
0566-reshape-the-matrix
0735-asteroid-collision
0861-flipping-an-image
0874-backspace-string-compare
0898-transpose-matrix
1386-shift-2d-grid
1505-create-target-array-in-the-given-order
1642-water-bottles
1682-most-visited-sector-in-a-circular-track
2021-remove-all-occurrences-of-a-substring
2232-adding-spaces-to-a-string
2411-spiral-matrix-iv
2470-removing-stars-from-a-string
2551-apply-operations-to-an-array
3434-find-the-number-of-distinct-colors-among-the-balls
3447-clear-digits

Recursion

0021-merge-two-sorted-lists
0024-swap-nodes-in-pairs
0050-powx-n
0203-remove-linked-list-elements
0206-reverse-linked-list
0231-power-of-two
0394-decode-string
1013-fibonacci-number

Two Pointers

0011-container-with-most-water
0031-next-permutation
0075-sort-colors
0080-remove-duplicates-from-sorted-array-ii
0082-remove-duplicates-from-sorted-list-ii
0086-partition-list
0142-linked-list-cycle-ii
0148-sort-list
0151-reverse-words-in-a-string
0189-rotate-array
0202-happy-number
0283-move-zeroes
0344-reverse-string
0349-intersection-of-two-arrays
0350-intersection-of-two-arrays-ii
0392-is-subsequence
0443-string-compression
0455-assign-cookies
0522-longest-uncommon-subsequence-ii
0841-shortest-distance-to-a-character
0861-flipping-an-image
0868-push-dominoes
0874-backspace-string-compare
0908-middle-of-the-linked-list
0917-boats-to-save-people
0941-sort-array-by-parity
0961-long-pressed-name
1566-check-if-a-word-occurs-as-a-prefix-of-any-word-in-a-sentence
1798-max-number-of-k-sum-pairs
2232-adding-spaces-to-a-string
2392-successful-pairs-of-spells-and-potions
2551-apply-operations-to-an-array
2581-divide-players-into-teams-of-equal-skill
3018-make-string-a-subsequence-using-cyclic-increments

Hash Table

0001-two-sum
0012-integer-to-roman
0013-roman-to-integer
0049-group-anagrams
0073-set-matrix-zeroes
0105-construct-binary-tree-from-preorder-and-inorder-traversal
0106-construct-binary-tree-from-inorder-and-postorder-traversal
0133-clone-graph
0139-word-break
0142-linked-list-cycle-ii
0166-fraction-to-recurring-decimal
0169-majority-element
0187-repeated-dna-sequences
0202-happy-number
0217-contains-duplicate
0219-contains-duplicate-ii
0229-majority-element-ii
0242-valid-anagram
0264-ugly-number-ii
0268-missing-number
0299-bulls-and-cows
0349-intersection-of-two-arrays
0350-intersection-of-two-arrays-ii
0387-first-unique-character-in-a-string
0389-find-the-difference
0424-longest-repeating-character-replacement
0454-4sum-ii
0522-longest-uncommon-subsequence-ii
0523-continuous-subarray-sum
0599-minimum-index-sum-of-two-lists
0645-set-mismatch
0697-degree-of-an-array
0822-unique-morse-code-words
0837-most-common-word
0924-fair-candy-swap
0925-construct-binary-tree-from-preorder-and-postorder-traversal
0965-unique-email-addresses
1001-n-repeated-element-in-size-2n-array
1039-find-the-town-judge
1044-find-common-characters
1364-tuple-with-same-product
1392-find-the-difference-of-two-arrays
1473-find-the-longest-substring-containing-vowels-in-even-counts
1482-how-many-numbers-are-smaller-than-the-current-number
1500-count-largest-group
1556-make-two-arrays-equal-by-reversing-subarrays
1619-path-crossing
1635-number-of-good-pairs
1694-make-sum-divisible-by-p
1777-determine-if-two-strings-are-close
1798-max-number-of-k-sum-pairs
1960-check-if-the-sentence-is-pangram
2215-finding-3-digit-even-numbers
2220-find-all-possible-recipes-from-given-supplies
2237-longest-palindrome-by-concatenating-two-letter-words
2434-design-a-number-container-system
2448-count-number-of-bad-pairs
2581-divide-players-into-teams-of-equal-skill
2626-count-the-number-of-good-subarrays
3434-find-the-number-of-distinct-colors-among-the-balls
3445-lexicographically-minimum-string-after-removing-stars
3753-maximum-difference-between-even-and-odd-frequency-i

String

0012-integer-to-roman
0013-roman-to-integer
0014-longest-common-prefix
0049-group-anagrams
0058-length-of-last-word
0071-simplify-path
0072-edit-distance
0079-word-search
0091-decode-ways
0093-restore-ip-addresses
0097-interleaving-string
0131-palindrome-partitioning
0139-word-break
0151-reverse-words-in-a-string
0166-fraction-to-recurring-decimal
0168-excel-sheet-column-title
0171-excel-sheet-column-number
0187-repeated-dna-sequences
0227-basic-calculator-ii
0242-valid-anagram
0299-bulls-and-cows
0344-reverse-string
0387-first-unique-character-in-a-string
0389-find-the-difference
0392-is-subsequence
0394-decode-string
0424-longest-repeating-character-replacement
0443-string-compression
0459-repeated-substring-pattern
0467-unique-substrings-in-wraparound-string
0521-longest-uncommon-subsequence-i
0522-longest-uncommon-subsequence-ii
0551-student-attendance-record-i
0599-minimum-index-sum-of-two-lists
0649-dota2-senate
0742-to-lower-case
0800-letter-case-permutation
0812-rotate-string
0822-unique-morse-code-words
0824-number-of-lines-to-write-string
0837-most-common-word
0841-shortest-distance-to-a-character
0868-push-dominoes
0874-backspace-string-compare
0961-long-pressed-name
0965-unique-email-addresses
1044-find-common-characters
1250-longest-common-subsequence
1274-number-of-days-between-two-dates
1341-split-a-string-in-balanced-strings
1473-find-the-longest-substring-containing-vowels-in-even-counts
1490-generate-a-string-with-characters-that-have-odd-counts
1542-consecutive-characters
1566-check-if-a-word-occurs-as-a-prefix-of-any-word-in-a-sentence
1619-path-crossing
1777-determine-if-two-strings-are-close
1960-check-if-the-sentence-is-pangram
2021-remove-all-occurrences-of-a-substring
2220-find-all-possible-recipes-from-given-supplies
2232-adding-spaces-to-a-string
2237-longest-palindrome-by-concatenating-two-letter-words
2456-construct-smallest-number-from-di-string
2463-minimum-recolors-to-get-k-consecutive-black-blocks
2470-removing-stars-from-a-string
3018-make-string-a-subsequence-using-cyclic-increments
3194-find-words-containing-character
3445-lexicographically-minimum-string-after-removing-stars
3447-clear-digits
3753-maximum-difference-between-even-and-odd-frequency-i

Sorting

0049-group-anagrams
0056-merge-intervals
0075-sort-colors
0148-sort-list
0169-majority-element
0215-kth-largest-element-in-an-array
0217-contains-duplicate
0229-majority-element-ii
0242-valid-anagram
0268-missing-number
0274-h-index
0349-intersection-of-two-arrays
0350-intersection-of-two-arrays-ii
0389-find-the-difference
0455-assign-cookies
0522-longest-uncommon-subsequence-ii
0561-array-partition
0645-set-mismatch
0748-largest-number-at-least-twice-of-others
0917-boats-to-save-people
0924-fair-candy-swap
0941-sort-array-by-parity
1018-largest-perimeter-triangle
1047-maximize-sum-of-array-after-k-negations
1137-height-checker
1458-sort-integers-by-the-number-of-1-bits
1482-how-many-numbers-are-smaller-than-the-current-number
1556-make-two-arrays-equal-by-reversing-subarrays
1626-can-make-arithmetic-progression-from-sequence
1777-determine-if-two-strings-are-close
1798-max-number-of-k-sum-pairs
2215-finding-3-digit-even-numbers
2379-maximum-total-importance-of-roads
2392-successful-pairs-of-spells-and-potions
2581-divide-players-into-teams-of-equal-skill
3321-type-of-triangle
3430-count-days-without-meetings
3647-zero-array-transformation-iii

Math

0012-integer-to-roman
0013-roman-to-integer
0050-powx-n
0062-unique-paths
0089-gray-code
0166-fraction-to-recurring-decimal
0168-excel-sheet-column-title
0171-excel-sheet-column-number
0172-factorial-trailing-zeroes
0189-rotate-array
0202-happy-number
0204-count-primes
0227-basic-calculator-ii
0231-power-of-two
0258-add-digits
0263-ugly-number
0264-ugly-number-ii
0268-missing-number
0279-perfect-squares
0292-nim-game
0367-valid-perfect-square
0371-sum-of-two-integers
0400-nth-digit
0504-base-7
0507-perfect-number
0523-continuous-subarray-sum
0598-range-addition-ii
0767-prime-number-of-set-bits-in-binary-representation
0866-rectangle-overlap
0944-smallest-range-i
1013-fibonacci-number
1018-largest-perimeter-triangle
1031-add-to-array-form-of-integer
1115-valid-boomerang
1236-n-th-tribonacci-number
1274-number-of-days-between-two-dates
1421-find-numbers-with-even-number-of-digits
1448-maximum-69-number
1477-product-of-the-last-k-numbers
1500-count-largest-group
1630-count-odd-numbers-in-an-interval-range
1635-number-of-good-pairs
1642-water-bottles
2448-count-number-of-bad-pairs
2704-maximum-difference-by-remapping-a-digit
2802-find-the-punishment-number-of-an-integer
3321-type-of-triangle

Bit Manipulation

0089-gray-code
0090-subsets-ii
0187-repeated-dna-sequences
0190-reverse-bits
0191-number-of-1-bits
0231-power-of-two
0268-missing-number
0338-counting-bits
0371-sum-of-two-integers
0389-find-the-difference
0397-integer-replacement
0461-hamming-distance
0476-number-complement
0645-set-mismatch
0693-binary-number-with-alternating-bits
0767-prime-number-of-set-bits-in-binary-representation
0800-letter-case-permutation
0861-flipping-an-image
1458-sort-integers-by-the-number-of-1-bits
1473-find-the-longest-substring-containing-vowels-in-even-counts
2323-minimum-bit-flips-to-convert-number
2478-longest-nice-subarray
2503-longest-subarray-with-maximum-bitwise-and
3348-minimum-cost-walk-in-weighted-graph

Brainteaser

0292-nim-game
2503-longest-subarray-with-maximum-bitwise-and

Divide and Conquer

0053-maximum-subarray
0105-construct-binary-tree-from-preorder-and-inorder-traversal
0106-construct-binary-tree-from-inorder-and-postorder-traversal
0109-convert-sorted-list-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
0240-search-a-2d-matrix-ii
0925-construct-binary-tree-from-preorder-and-postorder-traversal

Counting

0169-majority-element
0229-majority-element-ii
0299-bulls-and-cows
0387-first-unique-character-in-a-string
0837-most-common-word
1341-split-a-string-in-balanced-strings
1364-tuple-with-same-product
1458-sort-integers-by-the-number-of-1-bits
1482-how-many-numbers-are-smaller-than-the-current-number
1635-number-of-good-pairs
1777-determine-if-two-strings-are-close
2237-longest-palindrome-by-concatenating-two-letter-words
2448-count-number-of-bad-pairs
2614-maximum-count-of-positive-integer-and-negative-integer
3753-maximum-difference-between-even-and-odd-frequency-i

Prefix Sum

0209-minimum-size-subarray-sum
0238-product-of-array-except-self
0523-continuous-subarray-sum
0724-find-pivot-index
1046-max-consecutive-ones-iii
1473-find-the-longest-substring-containing-vowels-in-even-counts
1477-product-of-the-last-k-numbers
1694-make-sum-divisible-by-p
1833-find-the-highest-altitude
2394-count-subarrays-with-score-less-than-k
3639-zero-array-transformation-i
3643-zero-array-transformation-ii
3647-zero-array-transformation-iii

Sliding Window

0187-repeated-dna-sequences
0209-minimum-size-subarray-sum
0219-contains-duplicate-ii
0424-longest-repeating-character-replacement
0643-maximum-average-subarray-i
1046-max-consecutive-ones-iii
2394-count-subarrays-with-score-less-than-k
2463-minimum-recolors-to-get-k-consecutive-black-blocks
2478-longest-nice-subarray
2626-count-the-number-of-good-subarrays
3483-alternating-groups-ii

Dynamic Programming

0045-jump-game-ii
0053-maximum-subarray
0055-jump-game
0062-unique-paths
0063-unique-paths-ii
0064-minimum-path-sum
0072-edit-distance
0091-decode-ways
0095-unique-binary-search-trees-ii
0097-interleaving-string
0120-triangle
0121-best-time-to-buy-and-sell-stock
0122-best-time-to-buy-and-sell-stock-ii
0131-palindrome-partitioning
0139-word-break
0152-maximum-product-subarray
0198-house-robber
0213-house-robber-ii
0221-maximal-square
0264-ugly-number-ii
0279-perfect-squares
0300-longest-increasing-subsequence
0309-best-time-to-buy-and-sell-stock-with-cooldown
0338-counting-bits
0392-is-subsequence
0397-integer-replacement
0467-unique-substrings-in-wraparound-string
0714-best-time-to-buy-and-sell-stock-with-transaction-fee
0747-min-cost-climbing-stairs
0806-domino-and-tromino-tiling
0868-push-dominoes
1013-fibonacci-number
1236-n-th-tribonacci-number
1250-longest-common-subsequence

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
0334-increasing-triplet-subsequence
0397-integer-replacement
0455-assign-cookies
0561-array-partition
0605-can-place-flowers
0649-dota2-senate
0714-best-time-to-buy-and-sell-stock-with-transaction-fee
0917-boats-to-save-people
1018-largest-perimeter-triangle
1047-maximize-sum-of-array-after-k-negations
1062-partition-array-into-three-parts-with-equal-sum
1341-split-a-string-in-balanced-strings
1448-maximum-69-number
2237-longest-palindrome-by-concatenating-two-letter-words
2379-maximum-total-importance-of-roads
2456-construct-smallest-number-from-di-string
2704-maximum-difference-by-remapping-a-digit
3445-lexicographically-minimum-string-after-removing-stars
3647-zero-array-transformation-iii

Design

0225-implement-stack-using-queues
0232-implement-queue-using-stacks
0859-design-circular-deque
0969-number-of-recent-calls
1477-product-of-the-last-k-numbers
2434-design-a-number-container-system

Queue

0225-implement-stack-using-queues
0232-implement-queue-using-stacks
0387-first-unique-character-in-a-string
0649-dota2-senate
0859-design-circular-deque
0969-number-of-recent-calls

Combinatorics

0062-unique-paths

Stack

0071-simplify-path
0114-flatten-binary-tree-to-linked-list
0225-implement-stack-using-queues
0227-basic-calculator-ii
0232-implement-queue-using-stacks
0394-decode-string
0456-132-pattern
0735-asteroid-collision
0874-backspace-string-compare
2021-remove-all-occurrences-of-a-substring
2456-construct-smallest-number-from-di-string
2470-removing-stars-from-a-string
3445-lexicographically-minimum-string-after-removing-stars
3447-clear-digits

Binary Search

0033-search-in-rotated-sorted-array
0074-search-a-2d-matrix
0081-search-in-rotated-sorted-array-ii
0153-find-minimum-in-rotated-sorted-array
0162-find-peak-element
0209-minimum-size-subarray-sum
0240-search-a-2d-matrix-ii
0268-missing-number
0275-h-index-ii
0300-longest-increasing-subsequence
0349-intersection-of-two-arrays
0350-intersection-of-two-arrays-ii
0367-valid-perfect-square
0374-guess-number-higher-or-lower
0400-nth-digit
0456-132-pattern
0745-find-smallest-letter-greater-than-target
0792-binary-search
0907-koko-eating-bananas
0924-fair-candy-swap
1046-max-consecutive-ones-iii
1476-count-negative-numbers-in-a-sorted-matrix
2392-successful-pairs-of-spells-and-potions
2394-count-subarrays-with-score-less-than-k
2614-maximum-count-of-positive-integer-and-negative-integer
3643-zero-array-transformation-ii

Trie

0014-longest-common-prefix
0139-word-break
0386-lexicographical-numbers

Memoization

0139-word-break
0397-integer-replacement
1013-fibonacci-number
1236-n-th-tribonacci-number

Tree

0095-unique-binary-search-trees-ii
0098-validate-binary-search-tree
0099-recover-binary-search-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
0107-binary-tree-level-order-traversal-ii
0109-convert-sorted-list-to-binary-search-tree
0110-balanced-binary-tree
0113-path-sum-ii
0114-flatten-binary-tree-to-linked-list
0226-invert-binary-tree
0230-kth-smallest-element-in-a-bst
0235-lowest-common-ancestor-of-a-binary-search-tree
0437-path-sum-iii
0450-delete-node-in-a-bst
0530-minimum-absolute-difference-in-bst
0617-merge-two-binary-trees
0925-construct-binary-tree-from-preorder-and-postorder-traversal
1079-sum-of-root-to-leaf-binary-numbers

Breadth-First Search

0102-binary-tree-level-order-traversal
0103-binary-tree-zigzag-level-order-traversal
0104-maximum-depth-of-binary-tree
0107-binary-tree-level-order-traversal-ii
0130-surrounded-regions
0133-clone-graph
0226-invert-binary-tree
0279-perfect-squares
0463-island-perimeter
0530-minimum-absolute-difference-in-bst
0617-merge-two-binary-trees
0871-keys-and-rooms
1036-rotting-oranges
2793-count-the-number-of-complete-components

Binary Tree

0095-unique-binary-search-trees-ii
0098-validate-binary-search-tree
0099-recover-binary-search-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
0107-binary-tree-level-order-traversal-ii
0109-convert-sorted-list-to-binary-search-tree
0110-balanced-binary-tree
0113-path-sum-ii
0114-flatten-binary-tree-to-linked-list
0226-invert-binary-tree
0230-kth-smallest-element-in-a-bst
0235-lowest-common-ancestor-of-a-binary-search-tree
0437-path-sum-iii
0450-delete-node-in-a-bst
0530-minimum-absolute-difference-in-bst
0617-merge-two-binary-trees
0925-construct-binary-tree-from-preorder-and-postorder-traversal
1079-sum-of-root-to-leaf-binary-numbers

Backtracking

0077-combinations
0079-word-search
0089-gray-code
0090-subsets-ii
0093-restore-ip-addresses
0095-unique-binary-search-trees-ii
0113-path-sum-ii
0131-palindrome-partitioning
0216-combination-sum-iii
0800-letter-case-permutation
2456-construct-smallest-number-from-di-string
2802-find-the-punishment-number-of-an-integer

Depth-First Search

0098-validate-binary-search-tree
0099-recover-binary-search-tree
0104-maximum-depth-of-binary-tree
0110-balanced-binary-tree
0113-path-sum-ii
0114-flatten-binary-tree-to-linked-list
0130-surrounded-regions
0133-clone-graph
0226-invert-binary-tree
0230-kth-smallest-element-in-a-bst
0235-lowest-common-ancestor-of-a-binary-search-tree
0386-lexicographical-numbers
0437-path-sum-iii
0463-island-perimeter
0530-minimum-absolute-difference-in-bst
0617-merge-two-binary-trees
0871-keys-and-rooms
1079-sum-of-root-to-leaf-binary-numbers
2793-count-the-number-of-complete-components

Data Stream

0969-number-of-recent-calls
1477-product-of-the-last-k-numbers

Binary Search Tree

0095-unique-binary-search-trees-ii
0098-validate-binary-search-tree
0099-recover-binary-search-tree
0109-convert-sorted-list-to-binary-search-tree
0230-kth-smallest-element-in-a-bst
0235-lowest-common-ancestor-of-a-binary-search-tree
0450-delete-node-in-a-bst
0530-minimum-absolute-difference-in-bst

Graph

0133-clone-graph
0871-keys-and-rooms
1039-find-the-town-judge
2220-find-all-possible-recipes-from-given-supplies
2379-maximum-total-importance-of-roads
2793-count-the-number-of-complete-components
3348-minimum-cost-walk-in-weighted-graph

Game Theory

0292-nim-game

String Matching

0459-repeated-substring-pattern
0812-rotate-string
1566-check-if-a-word-occurs-as-a-prefix-of-any-word-in-a-sentence

Heap (Priority Queue)

0215-kth-largest-element-in-an-array
0264-ugly-number-ii
2379-maximum-total-importance-of-roads
2434-design-a-number-container-system
3445-lexicographically-minimum-string-after-removing-stars
3647-zero-array-transformation-iii

Quickselect

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

Merge Sort

0148-sort-list

Interactive

0374-guess-number-higher-or-lower

Enumeration

0204-count-primes
1656-count-good-triplets
1689-detect-pattern-of-length-m-repeated-k-or-more-times
2215-finding-3-digit-even-numbers

Number Theory

0204-count-primes
0258-add-digits

Counting Sort

0274-h-index
0561-array-partition
1137-height-checker

Union Find

0130-surrounded-regions
2793-count-the-number-of-complete-components
3348-minimum-cost-walk-in-weighted-graph

Rolling Hash

0187-repeated-dna-sequences

Hash Function

0187-repeated-dna-sequences

Monotonic Stack

0456-132-pattern

Ordered Set

0456-132-pattern
2434-design-a-number-container-system

Geometry

0866-rectangle-overlap
1115-valid-boomerang

Topological Sort

2220-find-all-possible-recipes-from-given-supplies