leet_codes

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

LeetCode Topics

Array

0004-median-of-two-sorted-arrays
0015-3sum
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
0041-first-missing-positive
0047-permutations-ii
0048-rotate-image
0066-plus-one
0075-sort-colors
0108-convert-sorted-array-to-binary-search-tree
0121-best-time-to-buy-and-sell-stock
0128-longest-consecutive-sequence
0136-single-number
0137-single-number-ii
0150-evaluate-reverse-polish-notation
0162-find-peak-element
0167-two-sum-ii-input-array-is-sorted
0217-contains-duplicate
0219-contains-duplicate-ii
0228-summary-ranges
0238-product-of-array-except-self
0260-single-number-iii
0283-move-zeroes
0303-range-sum-query-immutable
0347-top-k-frequent-elements
0349-intersection-of-two-arrays
0485-max-consecutive-ones
0560-subarray-sum-equals-k
0599-minimum-index-sum-of-two-lists
0643-maximum-average-subarray-i
0724-find-pivot-index
0735-asteroid-collision
0792-binary-search
0945-snakes-and-ladders
1293-three-consecutive-odds
1319-unique-number-of-occurrences
1392-find-the-difference-of-two-arrays
1421-find-numbers-with-even-number-of-digits
1426-find-n-unique-integers-sum-up-to-zero
1464-reduce-array-size-to-the-half
1510-find-lucky-integer-in-an-array
1528-kids-with-the-greatest-number-of-candies
1621-number-of-subsequences-that-satisfy-the-given-sum-condition
1798-max-number-of-k-sum-pairs
1833-find-the-highest-altitude
2048-build-array-from-permutation
2144-maximum-difference-between-increasing-elements
2204-find-subsequence-of-length-k-with-the-largest-sum
2215-finding-3-digit-even-numbers
2237-longest-palindrome-by-concatenating-two-letter-words
2277-count-equal-and-divisible-pairs-in-an-array
2320-find-all-k-distant-indices-in-an-array
2324-find-triangular-sum-of-an-array
2428-equal-row-and-column-pairs
3143-longest-unequal-adjacent-groups-subsequence-i
3194-find-words-containing-character
3307-find-the-maximum-sum-of-node-values
3321-type-of-triangle
3747-maximum-difference-between-adjacent-elements-in-a-circular-array
3773-minimum-pair-removal-to-sort-array-i

String

0003-longest-substring-without-repeating-characters
0006-zigzag-conversion
0008-string-to-integer-atoi
0012-integer-to-roman
0013-roman-to-integer
0014-longest-common-prefix
0017-letter-combinations-of-a-phone-number
0020-valid-parentheses
0028-find-the-index-of-the-first-occurrence-in-a-string
0032-longest-valid-parentheses
0038-count-and-say
0058-length-of-last-word
0067-add-binary
0071-simplify-path
0076-minimum-window-substring
0125-valid-palindrome
0151-reverse-words-in-a-string
0171-excel-sheet-column-number
0242-valid-anagram
0290-word-pattern
0344-reverse-string
0345-reverse-vowels-of-a-string
0392-is-subsequence
0412-fizz-buzz
0443-string-compression
0482-license-key-formatting
0599-minimum-index-sum-of-two-lists
0778-reorganize-string
1770-minimum-deletions-to-make-character-frequencies-unique
1894-merge-strings-alternately
1987-substrings-of-size-three-with-distinct-characters
2237-longest-palindrome-by-concatenating-two-letter-words
2260-divide-a-string-into-groups-of-size-k
2470-removing-stars-from-a-string
3143-longest-unequal-adjacent-groups-subsequence-i
3194-find-words-containing-character
3617-find-the-original-typed-string-i
3753-maximum-difference-between-even-and-odd-frequency-i

Dynamic Programming

0032-longest-valid-parentheses
0070-climbing-stairs
0121-best-time-to-buy-and-sell-stock
0338-counting-bits
0392-is-subsequence
1986-largest-color-value-in-a-directed-graph
2408-number-of-people-aware-of-a-secret
3143-longest-unequal-adjacent-groups-subsequence-i
3307-find-the-maximum-sum-of-node-values

Greedy

0778-reorganize-string
1464-reduce-array-size-to-the-half
1529-max-difference-you-can-get-from-changing-an-integer
1770-minimum-deletions-to-make-character-frequencies-unique
2237-longest-palindrome-by-concatenating-two-letter-words
2704-maximum-difference-by-remapping-a-digit
3143-longest-unequal-adjacent-groups-subsequence-i
3307-find-the-maximum-sum-of-node-values

Bit Manipulation

0067-add-binary
0136-single-number
0137-single-number-ii
0191-number-of-1-bits
0222-count-complete-tree-nodes
0231-power-of-two
0260-single-number-iii
0338-counting-bits
0342-power-of-four
3307-find-the-maximum-sum-of-node-values
3600-find-the-k-th-character-in-string-game-i

Tree

0094-binary-tree-inorder-traversal
0100-same-tree
0101-symmetric-tree
0104-maximum-depth-of-binary-tree
0108-convert-sorted-array-to-binary-search-tree
0110-balanced-binary-tree
0111-minimum-depth-of-binary-tree
0112-path-sum
0144-binary-tree-preorder-traversal
0145-binary-tree-postorder-traversal
0222-count-complete-tree-nodes
0226-invert-binary-tree
0501-find-mode-in-binary-search-tree
3307-find-the-maximum-sum-of-node-values
3633-maximize-the-number-of-target-nodes-after-connecting-trees-i
3645-maximize-the-number-of-target-nodes-after-connecting-trees-ii

Sorting

0015-3sum
0047-permutations-ii
0075-sort-colors
0148-sort-list
0217-contains-duplicate
0242-valid-anagram
0347-top-k-frequent-elements
0349-intersection-of-two-arrays
0778-reorganize-string
1464-reduce-array-size-to-the-half
1621-number-of-subsequences-that-satisfy-the-given-sum-condition
1770-minimum-deletions-to-make-character-frequencies-unique
1798-max-number-of-k-sum-pairs
2204-find-subsequence-of-length-k-with-the-largest-sum
2215-finding-3-digit-even-numbers
3307-find-the-maximum-sum-of-node-values
3321-type-of-triangle

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
0162-find-peak-element
0167-two-sum-ii-input-array-is-sorted
0222-count-complete-tree-nodes
0278-first-bad-version
0349-intersection-of-two-arrays
0374-guess-number-higher-or-lower
0792-binary-search
1621-number-of-subsequences-that-satisfy-the-given-sum-condition

Divide and Conquer

0004-median-of-two-sorted-arrays
0023-merge-k-sorted-lists
0108-convert-sorted-array-to-binary-search-tree
0148-sort-list
0191-number-of-1-bits
0347-top-k-frequent-elements

Linked List

0002-add-two-numbers
0019-remove-nth-node-from-end-of-list
0021-merge-two-sorted-lists
0023-merge-k-sorted-lists
0024-swap-nodes-in-pairs
0025-reverse-nodes-in-k-group
0061-rotate-list
0082-remove-duplicates-from-sorted-list-ii
0083-remove-duplicates-from-sorted-list
0086-partition-list
0092-reverse-linked-list-ii
0141-linked-list-cycle
0142-linked-list-cycle-ii
0148-sort-list
0203-remove-linked-list-elements
0206-reverse-linked-list
0234-palindrome-linked-list
0528-swapping-nodes-in-a-linked-list
0908-middle-of-the-linked-list
2182-find-the-minimum-and-maximum-number-of-nodes-between-critical-points
3773-minimum-pair-removal-to-sort-array-i

Hash Table

0003-longest-substring-without-repeating-characters
0012-integer-to-roman
0013-roman-to-integer
0017-letter-combinations-of-a-phone-number
0036-valid-sudoku
0041-first-missing-positive
0076-minimum-window-substring
0128-longest-consecutive-sequence
0141-linked-list-cycle
0142-linked-list-cycle-ii
0217-contains-duplicate
0219-contains-duplicate-ii
0242-valid-anagram
0290-word-pattern
0347-top-k-frequent-elements
0349-intersection-of-two-arrays
0560-subarray-sum-equals-k
0599-minimum-index-sum-of-two-lists
0778-reorganize-string
1319-unique-number-of-occurrences
1392-find-the-difference-of-two-arrays
1464-reduce-array-size-to-the-half
1510-find-lucky-integer-in-an-array
1770-minimum-deletions-to-make-character-frequencies-unique
1798-max-number-of-k-sum-pairs
1986-largest-color-value-in-a-directed-graph
1987-substrings-of-size-three-with-distinct-characters
2204-find-subsequence-of-length-k-with-the-largest-sum
2215-finding-3-digit-even-numbers
2237-longest-palindrome-by-concatenating-two-letter-words
2428-equal-row-and-column-pairs
3753-maximum-difference-between-even-and-odd-frequency-i
3773-minimum-pair-removal-to-sort-array-i

Sliding Window

0003-longest-substring-without-repeating-characters
0076-minimum-window-substring
0219-contains-duplicate-ii
0643-maximum-average-subarray-i
1987-substrings-of-size-three-with-distinct-characters

Counting

0347-top-k-frequent-elements
0778-reorganize-string
1510-find-lucky-integer-in-an-array
1986-largest-color-value-in-a-directed-graph
1987-substrings-of-size-three-with-distinct-characters
2237-longest-palindrome-by-concatenating-two-letter-words
3753-maximum-difference-between-even-and-odd-frequency-i

Graph

1986-largest-color-value-in-a-directed-graph
2438-find-closest-node-to-given-two-nodes

Topological Sort

1986-largest-color-value-in-a-directed-graph

Memoization

0070-climbing-stairs
1986-largest-color-value-in-a-directed-graph

Math

0002-add-two-numbers
0007-reverse-integer
0012-integer-to-roman
0013-roman-to-integer
0048-rotate-image
0066-plus-one
0067-add-binary
0069-sqrtx
0070-climbing-stairs
0150-evaluate-reverse-polish-notation
0171-excel-sheet-column-number
0231-power-of-two
0258-add-digits
0263-ugly-number
0292-nim-game
0326-power-of-three
0342-power-of-four
0412-fizz-buzz
1421-find-numbers-with-even-number-of-digits
1426-find-n-unique-integers-sum-up-to-zero
1440-convert-integer-to-the-sum-of-two-no-zero-integers
1529-max-difference-you-can-get-from-changing-an-integer
1642-water-bottles
2324-find-triangular-sum-of-an-array
2704-maximum-difference-by-remapping-a-digit
3172-divisible-and-non-divisible-sums-difference
3279-alice-and-bob-playing-flower-game
3321-type-of-triangle
3336-water-bottles-ii
3600-find-the-k-th-character-in-string-game-i
3830-find-closest-person

Depth-First Search

0094-binary-tree-inorder-traversal
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
0144-binary-tree-preorder-traversal
0145-binary-tree-postorder-traversal
0226-invert-binary-tree
0386-lexicographical-numbers
0501-find-mode-in-binary-search-tree
2438-find-closest-node-to-given-two-nodes
3633-maximize-the-number-of-target-nodes-after-connecting-trees-i
3645-maximize-the-number-of-target-nodes-after-connecting-trees-ii

Breadth-First Search

0100-same-tree
0101-symmetric-tree
0104-maximum-depth-of-binary-tree
0111-minimum-depth-of-binary-tree
0112-path-sum
0226-invert-binary-tree
0945-snakes-and-ladders
3633-maximize-the-number-of-target-nodes-after-connecting-trees-i
3645-maximize-the-number-of-target-nodes-after-connecting-trees-ii

Matrix

0036-valid-sudoku
0048-rotate-image
0945-snakes-and-ladders
2428-equal-row-and-column-pairs

Two Pointers

0015-3sum
0019-remove-nth-node-from-end-of-list
0028-find-the-index-of-the-first-occurrence-in-a-string
0031-next-permutation
0061-rotate-list
0075-sort-colors
0082-remove-duplicates-from-sorted-list-ii
0086-partition-list
0125-valid-palindrome
0141-linked-list-cycle
0142-linked-list-cycle-ii
0148-sort-list
0151-reverse-words-in-a-string
0167-two-sum-ii-input-array-is-sorted
0234-palindrome-linked-list
0283-move-zeroes
0344-reverse-string
0345-reverse-vowels-of-a-string
0349-intersection-of-two-arrays
0392-is-subsequence
0443-string-compression
0528-swapping-nodes-in-a-linked-list
0908-middle-of-the-linked-list
1621-number-of-subsequences-that-satisfy-the-given-sum-condition
1798-max-number-of-k-sum-pairs
1894-merge-strings-alternately
2320-find-all-k-distant-indices-in-an-array

Enumeration

2215-finding-3-digit-even-numbers

Simulation

0067-add-binary
0258-add-digits
0412-fizz-buzz
0735-asteroid-collision
1642-water-bottles
2048-build-array-from-permutation
2260-divide-a-string-into-groups-of-size-k
2324-find-triangular-sum-of-an-array
2408-number-of-people-aware-of-a-secret
2428-equal-row-and-column-pairs
2470-removing-stars-from-a-string
3336-water-bottles-ii
3600-find-the-k-th-character-in-string-game-i
3773-minimum-pair-removal-to-sort-array-i

Prefix Sum

0238-product-of-array-except-self
0303-range-sum-query-immutable
0560-subarray-sum-equals-k
0724-find-pivot-index
1833-find-the-highest-altitude

Trie

0014-longest-common-prefix
0386-lexicographical-numbers

Stack

0020-valid-parentheses
0032-longest-valid-parentheses
0071-simplify-path
0094-binary-tree-inorder-traversal
0144-binary-tree-preorder-traversal
0145-binary-tree-postorder-traversal
0150-evaluate-reverse-polish-notation
0155-min-stack
0225-implement-stack-using-queues
0232-implement-queue-using-stacks
0234-palindrome-linked-list
0735-asteroid-collision
2470-removing-stars-from-a-string

Binary Tree

0094-binary-tree-inorder-traversal
0100-same-tree
0101-symmetric-tree
0104-maximum-depth-of-binary-tree
0108-convert-sorted-array-to-binary-search-tree
0110-balanced-binary-tree
0111-minimum-depth-of-binary-tree
0112-path-sum
0144-binary-tree-preorder-traversal
0145-binary-tree-postorder-traversal
0222-count-complete-tree-nodes
0226-invert-binary-tree
0501-find-mode-in-binary-search-tree

Design

0155-min-stack
0225-implement-stack-using-queues
0232-implement-queue-using-stacks
0303-range-sum-query-immutable

Recursion

0002-add-two-numbers
0021-merge-two-sorted-lists
0024-swap-nodes-in-pairs
0025-reverse-nodes-in-k-group
0203-remove-linked-list-elements
0206-reverse-linked-list
0231-power-of-two
0234-palindrome-linked-list
0326-power-of-three
0342-power-of-four
3600-find-the-k-th-character-in-string-game-i

Backtracking

0017-letter-combinations-of-a-phone-number
0047-permutations-ii

String Matching

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

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
0586-customer-placing-the-largest-number-of-orders
1179-game-play-analysis-i

Binary Search Tree

0108-convert-sorted-array-to-binary-search-tree
0501-find-mode-in-binary-search-tree

Heap (Priority Queue)

0023-merge-k-sorted-lists
0347-top-k-frequent-elements
0778-reorganize-string
1464-reduce-array-size-to-the-half
2204-find-subsequence-of-length-k-with-the-largest-sum
3773-minimum-pair-removal-to-sort-array-i

Merge Sort

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

Doubly-Linked List

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

Ordered Set

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

Queue

0225-implement-stack-using-queues
0232-implement-queue-using-stacks
2408-number-of-people-aware-of-a-secret

Number Theory

0258-add-digits

Interactive

0278-first-bad-version
0374-guess-number-higher-or-lower

Brainteaser

0292-nim-game

Game Theory

0292-nim-game

Union Find

0128-longest-consecutive-sequence

Bucket Sort

0347-top-k-frequent-elements

Quickselect

0347-top-k-frequent-elements

Combinatorics

2324-find-triangular-sum-of-an-array