problem-solving

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

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
0033-search-in-rotated-sorted-array
0034-find-first-and-last-position-of-element-in-sorted-array
0035-search-insert-position
0046-permutations
0048-rotate-image
0049-group-anagrams
0053-maximum-subarray
0054-spiral-matrix
0074-search-a-2d-matrix
0075-sort-colors
0078-subsets
0081-search-in-rotated-sorted-array-ii
0088-merge-sorted-array
0090-subsets-ii
0121-best-time-to-buy-and-sell-stock
0122-best-time-to-buy-and-sell-stock-ii
0128-longest-consecutive-sequence
0130-surrounded-regions
0136-single-number
0152-maximum-product-subarray
0153-find-minimum-in-rotated-sorted-array
0167-two-sum-ii-input-array-is-sorted
0169-majority-element
0189-rotate-array
0198-house-robber
0200-number-of-islands
0213-house-robber-ii
0215-kth-largest-element-in-an-array
0217-contains-duplicate
0219-contains-duplicate-ii
0229-majority-element-ii
0238-product-of-array-except-self
0268-missing-number
0287-find-the-duplicate-number
0304-range-sum-query-2d-immutable
0322-coin-change
0347-top-k-frequent-elements
0416-partition-equal-subset-sum
0417-pacific-atlantic-water-flow
0442-find-all-duplicates-in-an-array
0448-find-all-numbers-disappeared-in-an-array
0463-island-perimeter
0485-max-consecutive-ones
0560-subarray-sum-equals-k
0643-maximum-average-subarray-i
0658-find-k-closest-elements
0682-baseball-game
0695-max-area-of-island
0713-subarray-product-less-than-k
0735-asteroid-collision
0739-daily-temperatures
0744-find-smallest-letter-greater-than-target
0746-min-cost-climbing-stairs
0752-open-the-lock
0792-binary-search
0816-design-hashset
0817-design-hashmap
0883-car-fleet
0904-fruit-into-baskets
0907-koko-eating-bananas
0948-sort-an-array
0953-verifying-an-alien-dictionary
0973-k-closest-points-to-origin
0994-rotting-oranges
0997-find-the-town-judge
1056-capacity-to-ship-packages-within-d-days
1481-least-number-of-unique-integers-after-k-removals
1539-kth-missing-positive-number
1574-shortest-subarray-to-be-removed-to-make-array-sorted
2058-concatenation-of-array

Hash Table

0001-two-sum
0003-longest-substring-without-repeating-characters
0049-group-anagrams
0128-longest-consecutive-sequence
0141-linked-list-cycle
0142-linked-list-cycle-ii
0169-majority-element
0202-happy-number
0205-isomorphic-strings
0217-contains-duplicate
0219-contains-duplicate-ii
0229-majority-element-ii
0242-valid-anagram
0268-missing-number
0347-top-k-frequent-elements
0442-find-all-duplicates-in-an-array
0448-find-all-numbers-disappeared-in-an-array
0451-sort-characters-by-frequency
0560-subarray-sum-equals-k
0752-open-the-lock
0767-reorganize-string
0816-design-hashset
0817-design-hashmap
0904-fruit-into-baskets
0953-verifying-an-alien-dictionary
0997-find-the-town-judge
1481-least-number-of-unique-integers-after-k-removals

Bit Manipulation

0078-subsets
0090-subsets-ii
0136-single-number
0268-missing-number
0287-find-the-duplicate-number
0784-letter-case-permutation

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
0081-search-in-rotated-sorted-array-ii
0153-find-minimum-in-rotated-sorted-array
0167-two-sum-ii-input-array-is-sorted
0268-missing-number
0287-find-the-duplicate-number
0374-guess-number-higher-or-lower
0658-find-k-closest-elements
0713-subarray-product-less-than-k
0744-find-smallest-letter-greater-than-target
0792-binary-search
0907-koko-eating-bananas
1056-capacity-to-ship-packages-within-d-days
1539-kth-missing-positive-number
1574-shortest-subarray-to-be-removed-to-make-array-sorted

Matrix

0048-rotate-image
0054-spiral-matrix
0074-search-a-2d-matrix
0130-surrounded-regions
0200-number-of-islands
0304-range-sum-query-2d-immutable
0417-pacific-atlantic-water-flow
0463-island-perimeter
0695-max-area-of-island
0994-rotting-oranges

Simulation

0054-spiral-matrix
0682-baseball-game
0735-asteroid-collision
0844-backspace-string-compare
2058-concatenation-of-array

Math

0048-rotate-image
0050-powx-n
0069-sqrtx
0070-climbing-stairs
0189-rotate-array
0202-happy-number
0268-missing-number
0509-fibonacci-number
0973-k-closest-points-to-origin
1137-n-th-tribonacci-number
2050-count-good-numbers

Divide and Conquer

0004-median-of-two-sorted-arrays
0023-merge-k-sorted-lists
0053-maximum-subarray
0169-majority-element
0215-kth-largest-element-in-an-array
0347-top-k-frequent-elements
0948-sort-an-array
0973-k-closest-points-to-origin

Dynamic Programming

0005-longest-palindromic-substring
0022-generate-parentheses
0053-maximum-subarray
0070-climbing-stairs
0121-best-time-to-buy-and-sell-stock
0122-best-time-to-buy-and-sell-stock-ii
0152-maximum-product-subarray
0198-house-robber
0213-house-robber-ii
0322-coin-change
0416-partition-equal-subset-sum
0509-fibonacci-number
0516-longest-palindromic-subsequence
0647-palindromic-substrings
0746-min-cost-climbing-stairs
1137-n-th-tribonacci-number
1143-longest-common-subsequence

String

0003-longest-substring-without-repeating-characters
0005-longest-palindromic-substring
0014-longest-common-prefix
0020-valid-parentheses
0022-generate-parentheses
0049-group-anagrams
0071-simplify-path
0151-reverse-words-in-a-string
0205-isomorphic-strings
0242-valid-anagram
0257-binary-tree-paths
0394-decode-string
0451-sort-characters-by-frequency
0516-longest-palindromic-subsequence
0647-palindromic-substrings
0680-valid-palindrome-ii
0752-open-the-lock
0767-reorganize-string
0784-letter-case-permutation
0812-rotate-string
0844-backspace-string-compare
0953-verifying-an-alien-dictionary
1078-remove-outermost-parentheses
1143-longest-common-subsequence
1894-merge-strings-alternately

Stack

0020-valid-parentheses
0071-simplify-path
0094-binary-tree-inorder-traversal
0143-reorder-list
0144-binary-tree-preorder-traversal
0234-palindrome-linked-list
0394-decode-string
0682-baseball-game
0735-asteroid-collision
0739-daily-temperatures
0844-backspace-string-compare
0883-car-fleet
1078-remove-outermost-parentheses
1574-shortest-subarray-to-be-removed-to-make-array-sorted

Two Pointers

0005-longest-palindromic-substring
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
0061-rotate-list
0075-sort-colors
0088-merge-sorted-array
0141-linked-list-cycle
0142-linked-list-cycle-ii
0143-reorder-list
0151-reverse-words-in-a-string
0167-two-sum-ii-input-array-is-sorted
0189-rotate-array
0202-happy-number
0234-palindrome-linked-list
0287-find-the-duplicate-number
0647-palindromic-substrings
0658-find-k-closest-elements
0680-valid-palindrome-ii
0844-backspace-string-compare
0876-middle-of-the-linked-list
1574-shortest-subarray-to-be-removed-to-make-array-sorted
1894-merge-strings-alternately

Trie

0014-longest-common-prefix

Sorting

0015-3sum
0016-3sum-closest
0018-4sum
0049-group-anagrams
0075-sort-colors
0088-merge-sorted-array
0169-majority-element
0215-kth-largest-element-in-an-array
0217-contains-duplicate
0229-majority-element-ii
0242-valid-anagram
0268-missing-number
0347-top-k-frequent-elements
0442-find-all-duplicates-in-an-array
0451-sort-characters-by-frequency
0658-find-k-closest-elements
0767-reorganize-string
0883-car-fleet
0948-sort-an-array
0973-k-closest-points-to-origin
1481-least-number-of-unique-integers-after-k-removals

String Matching

0572-subtree-of-another-tree
0812-rotate-string

Database

0197-rising-temperature
0570-managers-with-at-least-5-direct-reports
0577-employee-bonus
0620-not-boring-movies
1068-product-sales-analysis-i
1075-project-employees-i
1174-immediate-food-delivery-ii
1193-monthly-transactions-i
1211-queries-quality-and-percentage
1251-average-selling-price
1258-article-views-i
1378-replace-employee-id-with-the-unique-identifier
1415-students-and-examinations
1581-customer-who-visited-but-did-not-make-any-transactions
1661-average-time-of-process-per-machine
1683-invalid-tweets
1827-invalid-tweets
1934-confirmation-rate

Recursion

0021-merge-two-sorted-lists
0050-powx-n
0143-reorder-list
0206-reverse-linked-list
0234-palindrome-linked-list
0394-decode-string
0509-fibonacci-number
2050-count-good-numbers

Linked List

0019-remove-nth-node-from-end-of-list
0021-merge-two-sorted-lists
0023-merge-k-sorted-lists
0061-rotate-list
0141-linked-list-cycle
0142-linked-list-cycle-ii
0143-reorder-list
0206-reverse-linked-list
0234-palindrome-linked-list
0816-design-hashset
0817-design-hashmap
0876-middle-of-the-linked-list

Design

0304-range-sum-query-2d-immutable
0816-design-hashset
0817-design-hashmap

Hash Function

0572-subtree-of-another-tree
0816-design-hashset
0817-design-hashmap

Counting

0169-majority-element
0229-majority-element-ii
0347-top-k-frequent-elements
0451-sort-characters-by-frequency
0767-reorganize-string
1481-least-number-of-unique-integers-after-k-removals

Heap (Priority Queue)

0023-merge-k-sorted-lists
0215-kth-largest-element-in-an-array
0347-top-k-frequent-elements
0451-sort-characters-by-frequency
0658-find-k-closest-elements
0767-reorganize-string
0948-sort-an-array
0973-k-closest-points-to-origin

Merge Sort

0023-merge-k-sorted-lists
0948-sort-an-array

Bucket Sort

0347-top-k-frequent-elements
0451-sort-characters-by-frequency
0948-sort-an-array

Radix Sort

0948-sort-an-array

Counting Sort

0948-sort-an-array

Quickselect

0215-kth-largest-element-in-an-array
0347-top-k-frequent-elements
0973-k-closest-points-to-origin

Prefix Sum

0238-product-of-array-except-self
0304-range-sum-query-2d-immutable
0560-subarray-sum-equals-k
0713-subarray-product-less-than-k

Union Find

0128-longest-consecutive-sequence
0130-surrounded-regions
0200-number-of-islands
0695-max-area-of-island

Greedy

0011-container-with-most-water
0122-best-time-to-buy-and-sell-stock-ii
0680-valid-palindrome-ii
0767-reorganize-string
1481-least-number-of-unique-integers-after-k-removals

Sliding Window

0003-longest-substring-without-repeating-characters
0219-contains-duplicate-ii
0643-maximum-average-subarray-i
0658-find-k-closest-elements
0713-subarray-product-less-than-k
0904-fruit-into-baskets

Backtracking

0022-generate-parentheses
0046-permutations
0078-subsets
0090-subsets-ii
0113-path-sum-ii
0257-binary-tree-paths
0784-letter-case-permutation

Monotonic Stack

0739-daily-temperatures
0883-car-fleet
1574-shortest-subarray-to-be-removed-to-make-array-sorted

Interactive

0374-guess-number-higher-or-lower

Tree

0094-binary-tree-inorder-traversal
0098-validate-binary-search-tree
0100-same-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
0110-balanced-binary-tree
0111-minimum-depth-of-binary-tree
0112-path-sum
0113-path-sum-ii
0129-sum-root-to-leaf-numbers
0144-binary-tree-preorder-traversal
0199-binary-tree-right-side-view
0226-invert-binary-tree
0230-kth-smallest-element-in-a-bst
0235-lowest-common-ancestor-of-a-binary-search-tree
0257-binary-tree-paths
0450-delete-node-in-a-bst
0543-diameter-of-binary-tree
0572-subtree-of-another-tree
0700-search-in-a-binary-search-tree
0701-insert-into-a-binary-search-tree
1161-maximum-level-sum-of-a-binary-tree
1450-delete-leaves-with-a-given-value

Depth-First Search

0094-binary-tree-inorder-traversal
0098-validate-binary-search-tree
0100-same-tree
0104-maximum-depth-of-binary-tree
0110-balanced-binary-tree
0111-minimum-depth-of-binary-tree
0112-path-sum
0113-path-sum-ii
0129-sum-root-to-leaf-numbers
0130-surrounded-regions
0144-binary-tree-preorder-traversal
0199-binary-tree-right-side-view
0200-number-of-islands
0226-invert-binary-tree
0230-kth-smallest-element-in-a-bst
0235-lowest-common-ancestor-of-a-binary-search-tree
0257-binary-tree-paths
0417-pacific-atlantic-water-flow
0463-island-perimeter
0543-diameter-of-binary-tree
0572-subtree-of-another-tree
0695-max-area-of-island
1161-maximum-level-sum-of-a-binary-tree
1450-delete-leaves-with-a-given-value

Binary Tree

0094-binary-tree-inorder-traversal
0098-validate-binary-search-tree
0100-same-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
0110-balanced-binary-tree
0111-minimum-depth-of-binary-tree
0112-path-sum
0113-path-sum-ii
0129-sum-root-to-leaf-numbers
0144-binary-tree-preorder-traversal
0199-binary-tree-right-side-view
0226-invert-binary-tree
0230-kth-smallest-element-in-a-bst
0235-lowest-common-ancestor-of-a-binary-search-tree
0257-binary-tree-paths
0450-delete-node-in-a-bst
0543-diameter-of-binary-tree
0572-subtree-of-another-tree
0700-search-in-a-binary-search-tree
0701-insert-into-a-binary-search-tree
1161-maximum-level-sum-of-a-binary-tree
1450-delete-leaves-with-a-given-value

Breadth-First Search

0100-same-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
0130-surrounded-regions
0199-binary-tree-right-side-view
0200-number-of-islands
0226-invert-binary-tree
0322-coin-change
0417-pacific-atlantic-water-flow
0463-island-perimeter
0695-max-area-of-island
0752-open-the-lock
0994-rotting-oranges
1161-maximum-level-sum-of-a-binary-tree

Binary Search Tree

0098-validate-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
0700-search-in-a-binary-search-tree
0701-insert-into-a-binary-search-tree

Graph

0997-find-the-town-judge

Memoization

0070-climbing-stairs
0509-fibonacci-number
1137-n-th-tribonacci-number

Geometry

0973-k-closest-points-to-origin