Leetcode_Solutions

A collection of LeetCode questions to ace the coding interview!

LeetCode Topics

Array

0001-two-sum
0004-median-of-two-sorted-arrays
0014-longest-common-prefix
0026-remove-duplicates-from-sorted-array
0027-remove-element
0031-next-permutation
0034-find-first-and-last-position-of-element-in-sorted-array
0041-first-missing-positive
0042-trapping-rain-water
0045-jump-game-ii
0048-rotate-image
0049-group-anagrams
0053-maximum-subarray
0055-jump-game
0056-merge-intervals
0059-spiral-matrix-ii
0066-plus-one
0073-set-matrix-zeroes
0074-search-a-2d-matrix
0075-sort-colors
0080-remove-duplicates-from-sorted-array-ii
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
0123-best-time-to-buy-and-sell-stock-iii
0152-maximum-product-subarray
0167-two-sum-ii-input-array-is-sorted
0169-majority-element
0200-number-of-islands
0204-count-primes
0217-contains-duplicate
0238-product-of-array-except-self
0268-missing-number
0283-move-zeroes
0287-find-the-duplicate-number
0322-coin-change
0453-minimum-moves-to-equal-array-elements
0817-design-hashmap
0890-lemonade-change
1293-three-consecutive-odds
1350-remove-sub-folders-from-the-filesystem
1421-find-numbers-with-even-number-of-digits
1426-find-n-unique-integers-sum-up-to-zero
1468-check-if-n-and-its-double-exist
1505-create-target-array-in-the-given-order
1510-find-lucky-integer-in-an-array
1730-special-array-with-x-elements-greater-than-or-equal-x
1813-maximum-erasure-value
2104-operations-on-tree
2116-count-number-of-pairs-with-absolute-difference-k
2144-maximum-difference-between-increasing-elements
2262-solving-questions-with-brainpower
2265-partition-array-according-to-given-pivot
2320-find-all-k-distant-indices-in-an-array
2551-apply-operations-to-an-array
2614-maximum-count-of-positive-integer-and-negative-integer
2707-merge-two-2d-arrays-by-summing-values
2876-number-of-employees-who-met-the-target
3194-find-words-containing-character
3227-find-missing-and-repeated-values
3242-count-elements-with-maximum-frequency
3621-minimum-operations-to-make-array-values-equal-to-k
3743-reschedule-meetings-for-maximum-free-time-i
3773-minimum-pair-removal-to-sort-array-i
3778-transform-array-by-parity

Hash Table

0001-two-sum
0003-longest-substring-without-repeating-characters
0041-first-missing-positive
0049-group-anagrams
0073-set-matrix-zeroes
0160-intersection-of-two-linked-lists
0169-majority-element
0217-contains-duplicate
0268-missing-number
0817-design-hashmap
1264-maximum-number-of-words-you-can-type
1468-check-if-n-and-its-double-exist
1500-count-largest-group
1510-find-lucky-integer-in-an-array
1813-maximum-erasure-value
1904-second-largest-digit-in-a-string
2053-check-if-all-characters-have-equal-number-of-occurrences
2104-operations-on-tree
2116-count-number-of-pairs-with-absolute-difference-k
2377-check-if-number-has-equal-digit-count-and-digit-value
2707-merge-two-2d-arrays-by-summing-values
3227-find-missing-and-repeated-values
3242-count-elements-with-maximum-frequency
3621-minimum-operations-to-make-array-values-equal-to-k
3773-minimum-pair-removal-to-sort-array-i

Database

0175-combine-two-tables
0176-second-highest-salary
0177-nth-highest-salary
0178-rank-scores
0180-consecutive-numbers
0181-employees-earning-more-than-their-managers
0182-duplicate-emails
0183-customers-who-never-order
0184-department-highest-salary
0196-delete-duplicate-emails
0197-rising-temperature
0570-managers-with-at-least-5-direct-reports
0577-employee-bonus
0584-find-customer-referee
0585-investments-in-2016
0595-big-countries
0620-not-boring-movies
1153-product-sales-analysis-i
1161-project-employees-i
1258-article-views-i
1317-monthly-transactions-i
1338-queries-quality-and-percentage
1390-average-selling-price
1415-students-and-examinations
1509-replace-employee-id-with-the-unique-identifier
1724-customer-who-visited-but-did-not-make-any-transactions
1801-average-time-of-process-per-machine
1827-invalid-tweets
1908-recyclable-and-low-fat-products
2087-confirmation-rate

Math

0002-add-two-numbers
0007-reverse-integer
0009-palindrome-number
0048-rotate-image
0050-powx-n
0066-plus-one
0070-climbing-stairs
0204-count-primes
0268-missing-number
0441-arranging-coins
0453-minimum-moves-to-equal-array-elements
1013-fibonacci-number
1236-n-th-tribonacci-number
1411-convert-binary-number-in-a-linked-list-to-integer
1421-find-numbers-with-even-number-of-digits
1426-find-n-unique-integers-sum-up-to-zero
1448-maximum-69-number
1500-count-largest-group
1889-check-if-number-is-a-sum-of-powers-of-three
1920-determine-color-of-a-chessboard-square
2032-largest-odd-number-in-string
2083-three-divisors
2610-closest-prime-numbers-in-range
2649-count-total-number-of-colored-cells
2812-find-the-maximum-achievable-number
2903-insert-greatest-common-divisors-in-linked-list
2998-count-symmetric-integers
3227-find-missing-and-repeated-values
3600-find-the-k-th-character-in-string-game-i
3830-find-closest-person

Linked List

0002-add-two-numbers
0019-remove-nth-node-from-end-of-list
0021-merge-two-sorted-lists
0024-swap-nodes-in-pairs
0086-partition-list
0092-reverse-linked-list-ii
0160-intersection-of-two-linked-lists
0203-remove-linked-list-elements
0206-reverse-linked-list
0234-palindrome-linked-list
0237-delete-node-in-a-linked-list
0328-odd-even-linked-list
0528-swapping-nodes-in-a-linked-list
0817-design-hashmap
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
2299-merge-nodes-in-between-zeros
2573-remove-nodes-from-linked-list
2903-insert-greatest-common-divisors-in-linked-list
3773-minimum-pair-removal-to-sort-array-i

Two Pointers

0019-remove-nth-node-from-end-of-list
0026-remove-duplicates-from-sorted-array
0027-remove-element
0031-next-permutation
0042-trapping-rain-water
0075-sort-colors
0080-remove-duplicates-from-sorted-array-ii
0086-partition-list
0088-merge-sorted-array
0160-intersection-of-two-linked-lists
0167-two-sum-ii-input-array-is-sorted
0234-palindrome-linked-list
0283-move-zeroes
0287-find-the-duplicate-number
0528-swapping-nodes-in-a-linked-list
1468-check-if-n-and-its-double-exist
2216-delete-the-middle-node-of-a-linked-list
2265-partition-array-according-to-given-pivot
2320-find-all-k-distant-indices-in-an-array
2551-apply-operations-to-an-array
2707-merge-two-2d-arrays-by-summing-values

Recursion

0002-add-two-numbers
0021-merge-two-sorted-lists
0024-swap-nodes-in-pairs
0050-powx-n
0203-remove-linked-list-elements
0206-reverse-linked-list
0234-palindrome-linked-list
1013-fibonacci-number
2573-remove-nodes-from-linked-list
3600-find-the-k-th-character-in-string-game-i

String

0003-longest-substring-without-repeating-characters
0014-longest-common-prefix
0020-valid-parentheses
0049-group-anagrams
0058-length-of-last-word
1264-maximum-number-of-words-you-can-type
1350-remove-sub-folders-from-the-filesystem
1532-reformat-the-string
1904-second-largest-digit-in-a-string
1920-determine-color-of-a-chessboard-square
2032-largest-odd-number-in-string
2053-check-if-all-characters-have-equal-number-of-occurrences
2260-divide-a-string-into-groups-of-size-k
2346-largest-3-same-digit-number-in-string
2377-check-if-number-has-equal-digit-count-and-digit-value
3174-minimum-number-of-changes-to-make-binary-string-beautiful
3194-find-words-containing-character
3396-valid-word
3617-find-the-original-typed-string-i

Greedy

0045-jump-game-ii
0055-jump-game
0122-best-time-to-buy-and-sell-stock-ii
0890-lemonade-change
1448-maximum-69-number
2032-largest-odd-number-in-string
3743-reschedule-meetings-for-maximum-free-time-i

Simulation

0059-spiral-matrix-ii
1505-create-target-array-in-the-given-order
2260-divide-a-string-into-groups-of-size-k
2265-partition-array-according-to-given-pivot
2299-merge-nodes-in-between-zeros
2551-apply-operations-to-an-array
3600-find-the-k-th-character-in-string-game-i
3773-minimum-pair-removal-to-sort-array-i

Sorting

0049-group-anagrams
0056-merge-intervals
0075-sort-colors
0088-merge-sorted-array
0169-majority-element
0217-contains-duplicate
0268-missing-number
1468-check-if-n-and-its-double-exist
1730-special-array-with-x-elements-greater-than-or-equal-x
3778-transform-array-by-parity

Binary Search

0004-median-of-two-sorted-arrays
0034-find-first-and-last-position-of-element-in-sorted-array
0074-search-a-2d-matrix
0167-two-sum-ii-input-array-is-sorted
0268-missing-number
0287-find-the-duplicate-number
0441-arranging-coins
1468-check-if-n-and-its-double-exist
1730-special-array-with-x-elements-greater-than-or-equal-x
2614-maximum-count-of-positive-integer-and-negative-integer

Design

0817-design-hashmap
2104-operations-on-tree

Hash Function

0817-design-hashmap

Number Theory

0204-count-primes
2083-three-divisors
2610-closest-prime-numbers-in-range
2903-insert-greatest-common-divisors-in-linked-list

Stack

0020-valid-parentheses
0042-trapping-rain-water
0094-binary-tree-inorder-traversal
0144-binary-tree-preorder-traversal
0145-binary-tree-postorder-traversal
0234-palindrome-linked-list
2573-remove-nodes-from-linked-list

Matrix

0048-rotate-image
0059-spiral-matrix-ii
0073-set-matrix-zeroes
0074-search-a-2d-matrix
0200-number-of-islands
3227-find-missing-and-repeated-values

Counting

0169-majority-element
1510-find-lucky-integer-in-an-array
2053-check-if-all-characters-have-equal-number-of-occurrences
2116-count-number-of-pairs-with-absolute-difference-k
2377-check-if-number-has-equal-digit-count-and-digit-value
2614-maximum-count-of-positive-integer-and-negative-integer
3242-count-elements-with-maximum-frequency
3778-transform-array-by-parity

Monotonic Stack

0042-trapping-rain-water
2573-remove-nodes-from-linked-list

Dynamic Programming

0042-trapping-rain-water
0045-jump-game-ii
0053-maximum-subarray
0055-jump-game
0070-climbing-stairs
0118-pascals-triangle
0119-pascals-triangle-ii
0121-best-time-to-buy-and-sell-stock
0122-best-time-to-buy-and-sell-stock-ii
0123-best-time-to-buy-and-sell-stock-iii
0152-maximum-product-subarray
0322-coin-change
0338-counting-bits
1013-fibonacci-number
1236-n-th-tribonacci-number
2262-solving-questions-with-brainpower

Memoization

0070-climbing-stairs
1013-fibonacci-number
1236-n-th-tribonacci-number

Divide and Conquer

0004-median-of-two-sorted-arrays
0053-maximum-subarray
0169-majority-element

Bit Manipulation

0201-bitwise-and-of-numbers-range
0268-missing-number
0287-find-the-duplicate-number
0338-counting-bits
0461-hamming-distance
3600-find-the-k-th-character-in-string-game-i

Enumeration

0204-count-primes
2083-three-divisors
2998-count-symmetric-integers

Tree

0094-binary-tree-inorder-traversal
0100-same-tree
0101-symmetric-tree
0104-maximum-depth-of-binary-tree
0112-path-sum
0144-binary-tree-preorder-traversal
0145-binary-tree-postorder-traversal
2104-operations-on-tree

Depth-First Search

0094-binary-tree-inorder-traversal
0100-same-tree
0101-symmetric-tree
0104-maximum-depth-of-binary-tree
0112-path-sum
0144-binary-tree-preorder-traversal
0145-binary-tree-postorder-traversal
0200-number-of-islands
1350-remove-sub-folders-from-the-filesystem
2104-operations-on-tree

Breadth-First Search

0100-same-tree
0101-symmetric-tree
0104-maximum-depth-of-binary-tree
0112-path-sum
0200-number-of-islands
0322-coin-change
2104-operations-on-tree

Binary Tree

0094-binary-tree-inorder-traversal
0100-same-tree
0101-symmetric-tree
0104-maximum-depth-of-binary-tree
0112-path-sum
0144-binary-tree-preorder-traversal
0145-binary-tree-postorder-traversal

Heap (Priority Queue)

3773-minimum-pair-removal-to-sort-array-i

Doubly-Linked List

3773-minimum-pair-removal-to-sort-array-i

Ordered Set

3773-minimum-pair-removal-to-sort-array-i

Union Find

0200-number-of-islands

Trie

0014-longest-common-prefix
1350-remove-sub-folders-from-the-filesystem

Prefix Sum

0238-product-of-array-except-self

Sliding Window

0003-longest-substring-without-repeating-characters
1813-maximum-erasure-value
3743-reschedule-meetings-for-maximum-free-time-i