Leetcode Problems Solved

This repository contains my solutions to various problems I have solved on LeetCode. Each solution is accompanied by the problem statement and is implemented in an optimized manner.

📌 Repository Structure

Each problem is categorized based on DSA / SQL.

The solutions are implemented in Java for DSA and SQL for database related problems.

Every solution includes a well-structured explanation and comments.

🚀 How to Use

Clone the repository:

git clone https://github.com/tejasvi001/LeetcodeProblemsSolved.git

Navigate to the required topic folder.

Open the problem file to see the solution and explanation.

LeetCode Topics

Array

0001-two-sum
0004-median-of-two-sorted-arrays
0011-container-with-most-water
0015-3sum
0016-3sum-closest
0018-4sum
0026-remove-duplicates-from-sorted-array
0027-remove-element
0031-next-permutation
0033-search-in-rotated-sorted-array
0034-find-first-and-last-position-of-element-in-sorted-array
0035-search-insert-position
0036-valid-sudoku
0037-sudoku-solver
0042-trapping-rain-water
0046-permutations
0047-permutations-ii
0051-n-queens
0053-maximum-subarray
0054-spiral-matrix
0059-spiral-matrix-ii
0063-unique-paths-ii
0064-minimum-path-sum
0066-plus-one
0073-set-matrix-zeroes
0074-search-a-2d-matrix
0075-sort-colors
0078-subsets
0080-remove-duplicates-from-sorted-array-ii
0084-largest-rectangle-in-histogram
0088-merge-sorted-array
0108-convert-sorted-array-to-binary-search-tree
0118-pascals-triangle
0121-best-time-to-buy-and-sell-stock
0122-best-time-to-buy-and-sell-stock-ii
0136-single-number
0137-single-number-ii
0139-word-break
0152-maximum-product-subarray
0153-find-minimum-in-rotated-sorted-array
0162-find-peak-element
0167-two-sum-ii-input-array-is-sorted
0169-majority-element
0179-largest-number
0189-rotate-array
0198-house-robber
0204-count-primes
0215-kth-largest-element-in-an-array
0217-contains-duplicate
0229-majority-element-ii
0238-product-of-array-except-self
0239-sliding-window-maximum
0240-search-a-2d-matrix-ii
0260-single-number-iii
0268-missing-number
0283-move-zeroes
0287-find-the-duplicate-number
0303-range-sum-query-immutable
0322-coin-change
0334-increasing-triplet-subsequence
0347-top-k-frequent-elements
0416-partition-equal-subset-sum
0435-non-overlapping-intervals
0442-find-all-duplicates-in-an-array
0452-minimum-number-of-arrows-to-burst-balloons
0485-max-consecutive-ones
0494-target-sum
0496-next-greater-element-i
0498-diagonal-traverse
0503-next-greater-element-ii
0560-subarray-sum-equals-k
0605-can-place-flowers
0611-valid-triangle-number
0630-course-schedule-iii
0643-maximum-average-subarray-i
0646-maximum-length-of-pair-chain
0718-maximum-length-of-repeated-subarray
0733-flood-fill
0735-asteroid-collision
0739-daily-temperatures
0747-min-cost-climbing-stairs
0792-binary-search
0816-design-hashset
0817-design-hashmap
0860-design-circular-queue
0875-longest-mountain-in-array
0898-transpose-matrix
0954-maximum-sum-circular-subarray
1019-squares-of-a-sorted-array
1062-partition-array-into-three-parts-with-equal-sum
1184-car-pooling
1293-three-consecutive-odds
1353-find-resultant-array-after-removing-anagrams
1426-find-n-unique-integers-sum-up-to-zero
1476-count-negative-numbers-in-a-sorted-matrix
1510-find-lucky-integer-in-an-array
1528-kids-with-the-greatest-number-of-candies
1741-sort-array-by-increasing-frequency
1798-max-number-of-k-sum-pairs
1829-maximum-units-on-a-truck
1860-find-kth-largest-xor-coordinate-value
1917-maximum-average-pass-ratio
2113-find-the-kth-largest-integer-in-the-array
2132-convert-1d-array-into-2d-array
2148-minimum-number-of-moves-to-seat-everyone
2277-count-equal-and-divisible-pairs-in-an-array
2316-count-hills-and-valleys-in-an-array
2320-find-all-k-distant-indices-in-an-array
2331-intersection-of-multiple-arrays
2411-spiral-matrix-iv
2486-most-frequent-even-element
2714-left-and-right-sum-differences
2720-minimize-the-maximum-difference-of-pairs
2722-prime-in-diagonal
2756-buy-two-chocolates
2767-maximum-sum-with-exactly-k-elements
3093-sum-of-values-at-indices-with-k-set-bits
3242-count-elements-with-maximum-frequency
3251-maximum-area-of-longest-diagonal-rectangle
3277-find-the-number-of-ways-to-place-people-ii
3278-find-the-number-of-ways-to-place-people-i
3321-type-of-triangle
3639-zero-array-transformation-i
3747-maximum-difference-between-adjacent-elements-in-a-circular-array
3788-maximum-unique-subarray-sum-after-deletion
3827-implement-router
3832-minimum-cost-to-reach-every-position
3838-path-existence-queries-in-a-graph-i
3914-check-if-any-element-has-prime-frequency

Hash Table

0001-two-sum
0003-longest-substring-without-repeating-characters
0012-integer-to-roman
0013-roman-to-integer
0036-valid-sudoku
0037-sudoku-solver
0073-set-matrix-zeroes
0139-word-break
0141-linked-list-cycle
0142-linked-list-cycle-ii
0146-lru-cache
0160-intersection-of-two-linked-lists
0169-majority-element
0208-implement-trie-prefix-tree
0217-contains-duplicate
0229-majority-element-ii
0242-valid-anagram
0268-missing-number
0347-top-k-frequent-elements
0383-ransom-note
0442-find-all-duplicates-in-an-array
0451-sort-characters-by-frequency
0496-next-greater-element-i
0560-subarray-sum-equals-k
0653-two-sum-iv-input-is-a-bst
0816-design-hashset
0817-design-hashmap
0900-reordered-power-of-2
1218-lowest-common-ancestor-of-deepest-leaves
1264-maximum-number-of-words-you-can-type
1353-find-resultant-array-after-removing-anagrams
1510-find-lucky-integer-in-an-array
1741-sort-array-by-increasing-frequency
1798-max-number-of-k-sum-pairs
2331-intersection-of-multiple-arrays
2486-most-frequent-even-element
2825-minimize-string-length
3242-count-elements-with-maximum-frequency
3678-design-task-manager
3788-maximum-unique-subarray-sum-after-deletion
3827-implement-router
3838-path-existence-queries-in-a-graph-i
3914-check-if-any-element-has-prime-frequency

Binary Search

0004-median-of-two-sorted-arrays
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
0240-search-a-2d-matrix-ii
0268-missing-number
0287-find-the-duplicate-number
0374-guess-number-higher-or-lower
0611-valid-triangle-number
0718-maximum-length-of-repeated-subarray
0792-binary-search
1296-kth-ancestor-of-a-tree-node
1476-count-negative-numbers-in-a-sorted-matrix
2720-minimize-the-maximum-difference-of-pairs
3827-implement-router
3838-path-existence-queries-in-a-graph-i

Divide and Conquer

0004-median-of-two-sorted-arrays
0023-merge-k-sorted-lists
0053-maximum-subarray
0108-convert-sorted-array-to-binary-search-tree
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
0347-top-k-frequent-elements
0954-maximum-sum-circular-subarray
1860-find-kth-largest-xor-coordinate-value
2113-find-the-kth-largest-integer-in-the-array

Math

0002-add-two-numbers
0007-reverse-integer
0009-palindrome-number
0012-integer-to-roman
0013-roman-to-integer
0050-powx-n
0062-unique-paths
0066-plus-one
0067-add-binary
0069-sqrtx
0070-climbing-stairs
0172-factorial-trailing-zeroes
0189-rotate-array
0204-count-primes
0224-basic-calculator
0231-power-of-two
0258-add-digits
0268-missing-number
0342-power-of-four
0371-sum-of-two-integers
0412-fizz-buzz
0593-valid-square
0767-prime-number-of-set-bits-in-binary-representation
0900-reordered-power-of-2
1013-fibonacci-number
1146-greatest-common-divisor-of-strings
1236-n-th-tribonacci-number
1289-day-of-the-week
1411-convert-binary-number-in-a-linked-list-to-integer
1426-find-n-unique-integers-sum-up-to-zero
1440-convert-integer-to-the-sum-of-two-no-zero-integers
1448-maximum-69-number
2507-number-of-common-factors
2704-maximum-difference-by-remapping-a-digit
2722-prime-in-diagonal
3172-divisible-and-non-divisible-sums-difference
3277-find-the-number-of-ways-to-place-people-ii
3278-find-the-number-of-ways-to-place-people-i
3321-type-of-triangle
3336-water-bottles-ii
3462-vowels-game-in-a-string
3600-find-the-k-th-character-in-string-game-i
3830-find-closest-person
3914-check-if-any-element-has-prime-frequency

Two Pointers

0011-container-with-most-water
0015-3sum
0016-3sum-closest
0018-4sum
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
0031-next-permutation
0042-trapping-rain-water
0075-sort-colors
0080-remove-duplicates-from-sorted-array-ii
0082-remove-duplicates-from-sorted-list-ii
0088-merge-sorted-array
0125-valid-palindrome
0141-linked-list-cycle
0142-linked-list-cycle-ii
0143-reorder-list
0148-sort-list
0151-reverse-words-in-a-string
0160-intersection-of-two-linked-lists
0167-two-sum-ii-input-array-is-sorted
0189-rotate-array
0234-palindrome-linked-list
0283-move-zeroes
0287-find-the-duplicate-number
0295-find-median-from-data-stream
0344-reverse-string
0345-reverse-vowels-of-a-string
0392-is-subsequence
0443-string-compression
0528-swapping-nodes-in-a-linked-list
0611-valid-triangle-number
0653-two-sum-iv-input-is-a-bst
0875-longest-mountain-in-array
1019-squares-of-a-sorted-array
1798-max-number-of-k-sum-pairs
1894-merge-strings-alternately
2128-reverse-prefix-of-word
2216-delete-the-middle-node-of-a-linked-list
2320-find-all-k-distant-indices-in-an-array

Greedy

0011-container-with-most-water
0122-best-time-to-buy-and-sell-stock-ii
0179-largest-number
0334-increasing-triplet-subsequence
0435-non-overlapping-intervals
0452-minimum-number-of-arrows-to-burst-balloons
0605-can-place-flowers
0611-valid-triangle-number
0630-course-schedule-iii
0646-maximum-length-of-pair-chain
0678-valid-parenthesis-string
1062-partition-array-into-three-parts-with-equal-sum
1448-maximum-69-number
1829-maximum-units-on-a-truck
1917-maximum-average-pass-ratio
2148-minimum-number-of-moves-to-seat-everyone
2704-maximum-difference-by-remapping-a-digit
2720-minimize-the-maximum-difference-of-pairs
2756-buy-two-chocolates
2767-maximum-sum-with-exactly-k-elements
3788-maximum-unique-subarray-sum-after-deletion

String

0003-longest-substring-without-repeating-characters
0012-integer-to-roman
0013-roman-to-integer
0014-longest-common-prefix
0020-valid-parentheses
0022-generate-parentheses
0028-find-the-index-of-the-first-occurrence-in-a-string
0032-longest-valid-parentheses
0058-length-of-last-word
0067-add-binary
0125-valid-palindrome
0139-word-break
0151-reverse-words-in-a-string
0179-largest-number
0208-implement-trie-prefix-tree
0224-basic-calculator
0242-valid-anagram
0297-serialize-and-deserialize-binary-tree
0344-reverse-string
0345-reverse-vowels-of-a-string
0383-ransom-note
0392-is-subsequence
0394-decode-string
0412-fizz-buzz
0443-string-compression
0451-sort-characters-by-frequency
0678-valid-parenthesis-string
0812-rotate-string
1146-greatest-common-divisor-of-strings
1250-longest-common-subsequence
1264-maximum-number-of-words-you-can-type
1302-delete-characters-to-make-fancy-string
1353-find-resultant-array-after-removing-anagrams
1537-maximum-score-after-splitting-a-string
1567-maximum-number-of-vowels-in-a-substring-of-given-length
1894-merge-strings-alternately
2113-find-the-kth-largest-integer-in-the-array
2128-reverse-prefix-of-word
2260-divide-a-string-into-groups-of-size-k
2346-largest-3-same-digit-number-in-string
2401-count-asterisks
2470-removing-stars-from-a-string
2580-circular-sentence
2825-minimize-string-length
3396-valid-word
3451-string-compression-iii
3462-vowels-game-in-a-string
3617-find-the-original-typed-string-i
3618-find-the-original-typed-string-ii

Trie

0014-longest-common-prefix
0139-word-break
0208-implement-trie-prefix-tree

Linked List

0002-add-two-numbers
0019-remove-nth-node-from-end-of-list
0021-merge-two-sorted-lists
0023-merge-k-sorted-lists
0082-remove-duplicates-from-sorted-list-ii
0083-remove-duplicates-from-sorted-list
0092-reverse-linked-list-ii
0109-convert-sorted-list-to-binary-search-tree
0114-flatten-binary-tree-to-linked-list
0141-linked-list-cycle
0142-linked-list-cycle-ii
0143-reorder-list
0146-lru-cache
0148-sort-list
0160-intersection-of-two-linked-lists
0203-remove-linked-list-elements
0206-reverse-linked-list
0234-palindrome-linked-list
0328-odd-even-linked-list
0528-swapping-nodes-in-a-linked-list
0816-design-hashset
0817-design-hashmap
0838-design-linked-list
0860-design-circular-queue
1411-convert-binary-number-in-a-linked-list-to-integer
1765-merge-in-between-linked-lists
2216-delete-the-middle-node-of-a-linked-list
2411-spiral-matrix-iv

Recursion

0002-add-two-numbers
0021-merge-two-sorted-lists
0050-powx-n
0143-reorder-list
0203-remove-linked-list-elements
0206-reverse-linked-list
0224-basic-calculator
0231-power-of-two
0234-palindrome-linked-list
0342-power-of-four
0394-decode-string
1013-fibonacci-number
3600-find-the-k-th-character-in-string-game-i

Stack

0020-valid-parentheses
0032-longest-valid-parentheses
0042-trapping-rain-water
0084-largest-rectangle-in-histogram
0094-binary-tree-inorder-traversal
0114-flatten-binary-tree-to-linked-list
0143-reorder-list
0144-binary-tree-preorder-traversal
0155-min-stack
0173-binary-search-tree-iterator
0224-basic-calculator
0225-implement-stack-using-queues
0232-implement-queue-using-stacks
0234-palindrome-linked-list
0394-decode-string
0496-next-greater-element-i
0503-next-greater-element-ii
0678-valid-parenthesis-string
0735-asteroid-collision
0739-daily-temperatures
0775-n-ary-tree-preorder-traversal
0776-n-ary-tree-postorder-traversal
0937-online-stock-span
2128-reverse-prefix-of-word
2470-removing-stars-from-a-string

String Matching

0028-find-the-index-of-the-first-occurrence-in-a-string
0572-subtree-of-another-tree
0812-rotate-string

Dynamic Programming

0022-generate-parentheses
0032-longest-valid-parentheses
0042-trapping-rain-water
0053-maximum-subarray
0062-unique-paths
0063-unique-paths-ii
0064-minimum-path-sum
0070-climbing-stairs
0118-pascals-triangle
0121-best-time-to-buy-and-sell-stock
0122-best-time-to-buy-and-sell-stock-ii
0139-word-break
0152-maximum-product-subarray
0198-house-robber
0322-coin-change
0338-counting-bits
0392-is-subsequence
0416-partition-equal-subset-sum
0435-non-overlapping-intervals
0494-target-sum
0646-maximum-length-of-pair-chain
0678-valid-parenthesis-string
0718-maximum-length-of-repeated-subarray
0747-min-cost-climbing-stairs
0875-longest-mountain-in-array
0954-maximum-sum-circular-subarray
1013-fibonacci-number
1236-n-th-tribonacci-number
1250-longest-common-subsequence
1296-kth-ancestor-of-a-tree-node
3140-count-visited-nodes-in-a-directed-graph
3618-find-the-original-typed-string-ii

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
0287-find-the-duplicate-number
0338-counting-bits
0342-power-of-four
0371-sum-of-two-integers
0767-prime-number-of-set-bits-in-binary-representation
1860-find-kth-largest-xor-coordinate-value
3093-sum-of-values-at-indices-with-k-set-bits
3600-find-the-k-th-character-in-string-game-i

Simulation

0054-spiral-matrix
0059-spiral-matrix-ii
0067-add-binary
0258-add-digits
0412-fizz-buzz
0498-diagonal-traverse
0735-asteroid-collision
0898-transpose-matrix
1184-car-pooling
2132-convert-1d-array-into-2d-array
2260-divide-a-string-into-groups-of-size-k
2411-spiral-matrix-iv
2470-removing-stars-from-a-string
3336-water-bottles-ii
3600-find-the-k-th-character-in-string-game-i

Memoization

0070-climbing-stairs
0139-word-break
1013-fibonacci-number
1236-n-th-tribonacci-number
3140-count-visited-nodes-in-a-directed-graph

Matrix

0036-valid-sudoku
0037-sudoku-solver
0054-spiral-matrix
0059-spiral-matrix-ii
0063-unique-paths-ii
0064-minimum-path-sum
0073-set-matrix-zeroes
0074-search-a-2d-matrix
0240-search-a-2d-matrix-ii
0498-diagonal-traverse
0733-flood-fill
0898-transpose-matrix
1476-count-negative-numbers-in-a-sorted-matrix
1860-find-kth-largest-xor-coordinate-value
2132-convert-1d-array-into-2d-array
2411-spiral-matrix-iv
2722-prime-in-diagonal

Sorting

0015-3sum
0016-3sum-closest
0018-4sum
0047-permutations-ii
0075-sort-colors
0088-merge-sorted-array
0148-sort-list
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
0295-find-median-from-data-stream
0347-top-k-frequent-elements
0435-non-overlapping-intervals
0451-sort-characters-by-frequency
0452-minimum-number-of-arrows-to-burst-balloons
0611-valid-triangle-number
0630-course-schedule-iii
0646-maximum-length-of-pair-chain
0900-reordered-power-of-2
1019-squares-of-a-sorted-array
1184-car-pooling
1353-find-resultant-array-after-removing-anagrams
1741-sort-array-by-increasing-frequency
1798-max-number-of-k-sum-pairs
1829-maximum-units-on-a-truck
1860-find-kth-largest-xor-coordinate-value
2113-find-the-kth-largest-integer-in-the-array
2148-minimum-number-of-moves-to-seat-everyone
2331-intersection-of-multiple-arrays
2756-buy-two-chocolates
3277-find-the-number-of-ways-to-place-people-ii
3278-find-the-number-of-ways-to-place-people-i
3321-type-of-triangle

Tree

0094-binary-tree-inorder-traversal
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
0107-binary-tree-level-order-traversal-ii
0108-convert-sorted-array-to-binary-search-tree
0109-convert-sorted-list-to-binary-search-tree
0110-balanced-binary-tree
0111-minimum-depth-of-binary-tree
0112-path-sum
0114-flatten-binary-tree-to-linked-list
0129-sum-root-to-leaf-numbers
0144-binary-tree-preorder-traversal
0173-binary-search-tree-iterator
0199-binary-tree-right-side-view
0226-invert-binary-tree
0235-lowest-common-ancestor-of-a-binary-search-tree
0236-lowest-common-ancestor-of-a-binary-tree
0297-serialize-and-deserialize-binary-tree
0450-delete-node-in-a-bst
0543-diameter-of-binary-tree
0572-subtree-of-another-tree
0637-average-of-levels-in-binary-tree
0653-two-sum-iv-input-is-a-bst
0774-maximum-depth-of-n-ary-tree
0775-n-ary-tree-preorder-traversal
0776-n-ary-tree-postorder-traversal
0789-kth-largest-element-in-a-stream
1116-maximum-level-sum-of-a-binary-tree
1218-lowest-common-ancestor-of-deepest-leaves
1296-kth-ancestor-of-a-tree-node

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
0111-minimum-depth-of-binary-tree
0112-path-sum
0114-flatten-binary-tree-to-linked-list
0129-sum-root-to-leaf-numbers
0144-binary-tree-preorder-traversal
0199-binary-tree-right-side-view
0207-course-schedule
0210-course-schedule-ii
0226-invert-binary-tree
0235-lowest-common-ancestor-of-a-binary-search-tree
0236-lowest-common-ancestor-of-a-binary-tree
0297-serialize-and-deserialize-binary-tree
0543-diameter-of-binary-tree
0572-subtree-of-another-tree
0637-average-of-levels-in-binary-tree
0653-two-sum-iv-input-is-a-bst
0733-flood-fill
0774-maximum-depth-of-n-ary-tree
0775-n-ary-tree-preorder-traversal
0776-n-ary-tree-postorder-traversal
0801-is-graph-bipartite
1116-maximum-level-sum-of-a-binary-tree
1218-lowest-common-ancestor-of-deepest-leaves
1296-kth-ancestor-of-a-tree-node
2121-find-if-path-exists-in-graph

Binary Tree

0094-binary-tree-inorder-traversal
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
0107-binary-tree-level-order-traversal-ii
0108-convert-sorted-array-to-binary-search-tree
0109-convert-sorted-list-to-binary-search-tree
0110-balanced-binary-tree
0111-minimum-depth-of-binary-tree
0112-path-sum
0114-flatten-binary-tree-to-linked-list
0129-sum-root-to-leaf-numbers
0144-binary-tree-preorder-traversal
0173-binary-search-tree-iterator
0199-binary-tree-right-side-view
0226-invert-binary-tree
0235-lowest-common-ancestor-of-a-binary-search-tree
0236-lowest-common-ancestor-of-a-binary-tree
0297-serialize-and-deserialize-binary-tree
0450-delete-node-in-a-bst
0543-diameter-of-binary-tree
0572-subtree-of-another-tree
0637-average-of-levels-in-binary-tree
0653-two-sum-iv-input-is-a-bst
0789-kth-largest-element-in-a-stream
1116-maximum-level-sum-of-a-binary-tree
1218-lowest-common-ancestor-of-deepest-leaves

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
0107-binary-tree-level-order-traversal-ii
0111-minimum-depth-of-binary-tree
0112-path-sum
0199-binary-tree-right-side-view
0207-course-schedule
0210-course-schedule-ii
0226-invert-binary-tree
0297-serialize-and-deserialize-binary-tree
0322-coin-change
0637-average-of-levels-in-binary-tree
0653-two-sum-iv-input-is-a-bst
0733-flood-fill
0774-maximum-depth-of-n-ary-tree
0801-is-graph-bipartite
1116-maximum-level-sum-of-a-binary-tree
1218-lowest-common-ancestor-of-deepest-leaves
1296-kth-ancestor-of-a-tree-node
2121-find-if-path-exists-in-graph

Prefix Sum

0238-product-of-array-except-self
0303-range-sum-query-immutable
0560-subarray-sum-equals-k
1184-car-pooling
1537-maximum-score-after-splitting-a-string
1860-find-kth-largest-xor-coordinate-value
2714-left-and-right-sum-differences
3618-find-the-original-typed-string-ii
3639-zero-array-transformation-i

Binary Search Tree

0098-validate-binary-search-tree
0108-convert-sorted-array-to-binary-search-tree
0109-convert-sorted-list-to-binary-search-tree
0173-binary-search-tree-iterator
0235-lowest-common-ancestor-of-a-binary-search-tree
0450-delete-node-in-a-bst
0653-two-sum-iv-input-is-a-bst
0789-kth-largest-element-in-a-stream

Number Theory

0204-count-primes
0258-add-digits
2507-number-of-common-factors
2722-prime-in-diagonal
3914-check-if-any-element-has-prime-frequency

Monotonic Stack

0042-trapping-rain-water
0084-largest-rectangle-in-histogram
0496-next-greater-element-i
0503-next-greater-element-ii
0739-daily-temperatures
0937-online-stock-span

Database

0176-second-highest-salary
0181-employees-earning-more-than-their-managers
0196-delete-duplicate-emails
0197-rising-temperature
0570-managers-with-at-least-5-direct-reports
0577-employee-bonus
0584-find-customer-referee
0595-big-countries
0596-classes-more-than-5-students
0619-biggest-single-number
0620-not-boring-movies
1153-product-sales-analysis-i
1161-project-employees-i
1258-article-views-i
1390-average-selling-price
1462-list-the-products-ordered-in-a-period
1509-replace-employee-id-with-the-unique-identifier
1625-group-sold-products-by-the-date
1664-find-users-with-valid-e-mails
1670-patients-with-a-condition
1724-customer-who-visited-but-did-not-make-any-transactions
1801-average-time-of-process-per-machine
1811-fix-names-in-a-table
1827-invalid-tweets
1877-find-followers-count
1908-recyclable-and-low-fat-products
2127-employees-whose-manager-left-the-company
2495-number-of-unique-subjects-taught-by-each-teacher

Sliding Window

0003-longest-substring-without-repeating-characters
0239-sliding-window-maximum
0643-maximum-average-subarray-i
0718-maximum-length-of-repeated-subarray
1567-maximum-number-of-vowels-in-a-substring-of-given-length

Design

0146-lru-cache
0155-min-stack
0173-binary-search-tree-iterator
0208-implement-trie-prefix-tree
0225-implement-stack-using-queues
0232-implement-queue-using-stacks
0295-find-median-from-data-stream
0297-serialize-and-deserialize-binary-tree
0303-range-sum-query-immutable
0789-kth-largest-element-in-a-stream
0816-design-hashset
0817-design-hashmap
0838-design-linked-list
0860-design-circular-queue
0937-online-stock-span
0969-number-of-recent-calls
1296-kth-ancestor-of-a-tree-node
3678-design-task-manager
3827-implement-router

Queue

0225-implement-stack-using-queues
0232-implement-queue-using-stacks
0239-sliding-window-maximum
0860-design-circular-queue
0954-maximum-sum-circular-subarray
0969-number-of-recent-calls
3827-implement-router

Data Stream

0295-find-median-from-data-stream
0789-kth-largest-element-in-a-stream
0937-online-stock-span
0969-number-of-recent-calls

Interactive

0374-guess-number-higher-or-lower

Counting

0169-majority-element
0229-majority-element-ii
0347-top-k-frequent-elements
0383-ransom-note
0451-sort-characters-by-frequency
0900-reordered-power-of-2
1510-find-lucky-integer-in-an-array
2331-intersection-of-multiple-arrays
2486-most-frequent-even-element
3242-count-elements-with-maximum-frequency
3914-check-if-any-element-has-prime-frequency

Monotonic Queue

0239-sliding-window-maximum
0954-maximum-sum-circular-subarray

Hash Function

0572-subtree-of-another-tree
0718-maximum-length-of-repeated-subarray
0816-design-hashset
0817-design-hashmap

Heap (Priority Queue)

0023-merge-k-sorted-lists
0215-kth-largest-element-in-an-array
0239-sliding-window-maximum
0295-find-median-from-data-stream
0347-top-k-frequent-elements
0451-sort-characters-by-frequency
0630-course-schedule-iii
0789-kth-largest-element-in-a-stream
1184-car-pooling
1860-find-kth-largest-xor-coordinate-value
1917-maximum-average-pass-ratio
2113-find-the-kth-largest-integer-in-the-array
3678-design-task-manager

Quickselect

0215-kth-largest-element-in-an-array
0347-top-k-frequent-elements
1860-find-kth-largest-xor-coordinate-value
2113-find-the-kth-largest-integer-in-the-array

Bucket Sort

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

Merge Sort

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

Enumeration

0204-count-primes
0875-longest-mountain-in-array
0900-reordered-power-of-2
2507-number-of-common-factors
3277-find-the-number-of-ways-to-place-people-ii
3278-find-the-number-of-ways-to-place-people-i

Graph

0207-course-schedule
0210-course-schedule-ii
0801-is-graph-bipartite
2121-find-if-path-exists-in-graph
3140-count-visited-nodes-in-a-directed-graph
3838-path-existence-queries-in-a-graph-i

Union Find

0801-is-graph-bipartite
2121-find-if-path-exists-in-graph
3838-path-existence-queries-in-a-graph-i

Topological Sort

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

Backtracking

0022-generate-parentheses
0037-sudoku-solver
0046-permutations
0047-permutations-ii
0051-n-queens
0052-n-queens-ii
0078-subsets
0494-target-sum

Counting Sort

2148-minimum-number-of-moves-to-seat-everyone

Geometry

0593-valid-square
3277-find-the-number-of-ways-to-place-people-ii
3278-find-the-number-of-ways-to-place-people-i

Iterator

0173-binary-search-tree-iterator

Doubly-Linked List

0146-lru-cache

Combinatorics

0062-unique-paths

Brainteaser

3462-vowels-game-in-a-string

Game Theory

3462-vowels-game-in-a-string

Ordered Set

3678-design-task-manager
3827-implement-router

Rolling Hash

0718-maximum-length-of-repeated-subarray